tft lcd raspberry pi gpio pins brands

There are two ways of connecting a display to a Raspberry Pi - via the HDMI port or the GPIO pins/DSI cable. Depending on your project you may want to go one way or the other, to free up those valuable GPIO pins or have something compact and cable-free.

This section contains all of our GPIO and DSI connected Raspberry Pi displays. Almost every display here is connected via your Raspberry Pi GPIO pins, which usually means they"re more compact and remove the need to use an HDMI cable - which can keep your project nice and tidy when fitting into an enclosure or similar.

GPIO-connected Raspberry Pi displays aren"t always small either, we have GPIO/DSI screens ranging from ~2" up to ~7", giving you more choice and flexibility for your project.

As you can see pin 18 is used by the display for Instruction/Data Register selection. So, unfortunately you are not going to be able to use that pin for anything else. However there are other pins free so theoretically you could make something work. Just be careful about not pulling too much power from the Pi.

Also looking at the datasheet I suspect only pins 11, 19 and 21 are being used by the display. I"m fairly certain pin 18 is required. If you don"t need the functionality of a touchscreen, a display that connects to the DSI port might be more suitable and should leave pin 18 free.

the github LCD_Show script works well enough to get this LCD working on the Raspberry Pi 4 using the latest (at the time of this writing) release named Buster... what is not configured is the touchscreen coordinates, nor a very important configuration: right-click on a touchscreen...

- install the xinput-calibrator package, then run the program from either the desktop menu (Preferences) or from the command line of a terminal window; You"ll be shown a graphical screen, and asked to pen touch four different points on the display. When done you"ll be presented with a line of values representing your LCD"s touch boundaries, such as: "258 3966 3774 226" - Enter these values (as root) into the file 99-calibration.conf under the /etc/X11/xorg.conf.d directory, then reboot your RPi to enjoy more accuracy

folks, there"s no real magic here and no need to download a special "image" of a Raspbian distro... i don"t know why vendors make customers jump through insane hoops to get a product like this working... the screen is an XPT2046, aka "ADS7846," which is readily supported by the Linux kernel and Raspian releases

this display is a good deal and will provide a lot of fun - why vendors don"t make things easier for their customers i"ll never know... one of these days, Raspberry Pi users may benefit from vendors providing simple and easy instructions (Adafruit"s waveshare approach is convoluted as well and didn"t work for me)...

I bought this case with the intention of making a point and shoot style thermal camera. The project ended up being a success, but I found that the screen is a real GPIO hog. My specific issue was that it uses all of your default I2C headers. Other folks who actually know what they"re doing can probably work around this limitation with good circuit design, but since I"m an IT guy and not an engineer I had to make my hack work in software. This is by no means a fault with this case, and I am very happy with the finished product.

The screen is very responsive and worked well with a default raspberry pi image after following the included instructions. I did find that after installing the screen"s drivers, my external monitors started reporting "out of range", which I am sure is something that can be worked around in software. It wasn"t critical for my application, so I didn"t bother.

The only thing that I can say could use improvement would be to use a screen that exposes the GPIO pins so that things like sensors can be attached for noobs like me who can"t design circuits yet. That would make it a little more user friendly, but also understandably raise the price.

Is this not the cutest, little display for the Raspberry Pi? It features a 3.5″ display with 480×320 16-bit color pixels and a resistive touch overlay just like our popular original, but this one is engineered specifically to work with the newer “2×20 connector” Raspberry Pi’s. The plate uses the high speed SPI interface on the Pi and can use the mini display as a console, X window port, displaying images or video etc. Best of all it plugs right in on top!

ThisPiTFT 3.5″ is designed to fit nicely onto the Raspberry Pi Zero, Pi 3, Pi 2 or Model A+ / B+ (any Pi with a 2×20 connector). Not for use with an old Pi 1 with 2×13 connectorIf you’d like to use a 3.5″ display with the original Pi A or Pi B, check out this version

The display uses the hardware SPI pins (SCK, MOSI, MISO, CE0, CE1) as well as GPIO #25 and #24. GPIO #18 can be used to PWM dim the backlight if you like. All other GPIO are unused. There’s a 2×16 ‘classic Pi’ connection GPIO header on the bottom, you can connect a 26-pin Pi GPIO cable to it to use any of the other pins as you like. The other GPIO are broken out into solder pads at the bottom, in case you want to use more of the GPIO.

Best of all, it comes fully assembledand ready to plug into your Pi! You can use this as a display for running the X interface, or pygame. You can also have an HDMI display seperately connected. There’s four mounting ears that can be used to attach the display & Pi to a bezel, or snap them off with pliers (they’re perforated) for a slick exactly-the-same-size-as-a-Pi look.

The RPi LCD can be driven in two ways: Method 1. install driver to your Raspbian OS. Method 2. use the Ready-to-use image file of which LCD driver was pre-installed.

2) Connect the TF card to the PC, open the Win32DiskImager software, select the system image downloaded in step 1 and click‘Write’ to write the system image. ( How to write an image to a micro SD card for your Pi? See RPi Image Installation Guides for more details)

3) Connect the TF card to the Raspberry Pi, start the Raspberry Pi. The LCD will display after booting up, and then log in to the Raspberry Pi terminal,(You may need to connect a keyboard and HDMI LCD to Pi for driver installing, or log in remotely with SSH)

1. Executing apt-get upgrade will cause the LCD to fail to work properly. In this case, you need to edit the config.txt file in the SD card and delete this sentence: dtoverlay=ads7846.

This LCD can be calibrated through the xinput-calibrator program. Note: The Raspberry Pi must be connected to the network, or else the program won"t be successfully installed.

The touch screen LCD is ready with 320×480 resolution, 50 FPS (Frame per second). Resistive touch control is being supported by the Raspberry Pi OS or Raspbian (directly-pluggable). However, we will still need to install the driver for graphic display :)

However, there is a dedicated case/enclosure and a low-profile heatsink with a fan for this LCD to fit perfectly on the Raspberry Pi 4 Model B. The case has an opening for the LCD, and the low-profile heatsink with a fan keeps the Raspberry Pi 4 Model B protected and cool! You get a perfect console :) Don"t forget to remove the top lid/cover of the enclosure for the 3.5-inch LCD.

Note: The Raspberry Pi 4 Model B, 3.5-inch Enclosure, and the Low-Profile Heatsink with a fan are NOT INCLUDED in this product, please get them separately.

As we understand, Raspberry Pi 4 Model B delivers great performance and of course, more power will generate more heat as of all CPU :) So we need a way to install an additional heatsink to dissipate the extra heat. It will be better if we can have the option to add a cooling fan for active cooling. Well, this 3.5-inch touch screen LCD comes ready with the heatsink and cooling fan for you to use with the Raspberry Pi 4 Model B. it solves all the concerns.

The 3.5-inch touch screen uses the GPIO on the Raspberry Pi board, so it stretches out 2 pins as the power to supply the cooling fan on the low profile heatsink, and keep the Raspberry Pi board cool!

Note: The Raspberry Pi 4 Model B, 3.5-inch Enclosure, and the Low-Profile Heatsink with a fan are NOT INCLUDED in this product, please get them separately.

The Graphic driver is provided and can be downloaded for Raspberry Pi OS/Raspbian. It also supports Ubuntu and Kali Linux. Do follow the steps here: http://www.lcdwiki.com/MHS-3.5inch_RPi_Display

Note: Please use the recommended system for the touch screen. If another system is used, it may not have the touch function or may not work. You need to configure it yourself. Because there are many systems that the Raspberry Pi can use, we can’t make every system compatible with the touch screen.

Thanks for bringing this to my attention. It appears that the upgrade package overwrites the FBTFT drivers, in particular, the Raspberry Pi bootloader. This seems to solve the problem:

I just tested this, and it looks like the difference is how SPI is enabled. In the RPi 2 it’s enabled in raspi-config, not commented out in the blacklist file. I just updated the post so it should work now!

Looks like the only difference is in how SPI is enabled. In the new release of Raspbian, SPI is enabled in the raspi-config menu under advanced settings. In older versions of Raspbian, it is enabled by commenting out the line in the blacklist file

dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p6 rootfstype=ext4 elevator=deadline rootwait fbtft_device.custom fbtft_device.name=waveshare32b fbtft_device.gpios=dc:22,reset:27 fbtft_device.bgr=1 fbtft_device.speed=48000000 fbcon=map:10 fbcon=font:ProFont6x11 logo.nologo dma.dmachans=0x7f35 console=tty1 consoleblank=0 fbtft_device.fps=50 fbtft_device.rotate=0

Unfortunately, their “driver” is an SD card image containing a complete installation of Raspbian which has been preconfigured to use their display. Which is fine if you’re setting up a brand new system that doesn’t need to be a specific distro, but if you’re trying to add the display to an existing Raspberry Pi, already configured the way you want it, with software installed and data present, or if you want to use a specific distro such as Octopi, then it’s not terribly helpful.

Hello..I tired to interface this lcd “https://www.crazypi.com/raspberry-pi-products/Raspberry-Pi-Accessories/32-TOUCH-DISPLAY-RASPBERRY-PI” to my Raspberry pi model B+.I got a DVD containing image for LCD in the package.I burned it to the SD card and plugged in the display.But my lcd is completly blank.But green inidcation led (ACT LED) in board is blinking.Why my LCD is Blank ?

My Touchscreen is now working fine.The problem was for the ribbon cable on the back side of LCD.It was not connected properly.I just tighted the cable and it worked fine.Hope it will be useful tip.

Thank you for this great tutorial. I looked everywhere for this information. I have an eleduino 3.5 version A. I was able to get it working on my Pi 2 by following your tutorial and using flexfb as the screen type. I got the other settings from the image that came with the product. I did find that the ts_calibrate didn’t recognize the screen so I installed xinput-calibrator and it worked fine.

Just got my Pi2 running Wheezy, working with the Eleduino 3.5 LCD without running the OEMs image… kinda. I didn’t want to rebuild the application environment again, so was avoiding flashing the SD.

Unzipped it and looked around. From a shell script inside i kinda figured out what it was doing. I didn’t like what I saw, so I manually made changes omitting the parts I didn’t like (it rm -r my /lib/modules directory… omitted that part) and copied 2 files and 1 directory from the OEMs archive to the file system of my Pi2.

[ 0.000000] Kernel command line: dma.dmachans=0x7f35 bcm2708_fb.fbwidth=656 bcm2708_fb.fbheight=416 bcm2709.boardrev=0xa21041 bcm2709.serial=0x631a4eae smsc95xx.macaddr=B8:27:EB:1A:4E:AE bcm2708_fb.fbswap=1 bcm2709.disk_led_gpio=47 bcm2709.disk_led_active_low=0 sdhci-bcm2708.emmc_clock_freq=250000000 vc_mem.mem_base=0x3dc00000 vc_mem.mem_size=0x3f000000 dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait fbtft_device.custom fbtft_device.name=flexfb fbtft_device.gpios=dc:22,reset:27 fbtft_device.bgr=1 fbtft_device.speed=48000000 fbcon=map:10 fbcon=font:ProFont6x11 logo.nologo dma.dmachans=0x7f35 console=tty1 consoleblank=0 fbtft_device.fps=50 fbtft_device.rotate=0

thank you for your great tutorial, it got me on the right way. unfortunataly i only see some boot messages on the lcd and then it turns black. maybe you could give me a hint on how to get it working entirely.

i have a watterott display (https://github.com/watterott/RPi-Display) and changed the device-name to “rpi-display”. i use a rsapberrypi 2 and hae the latest raspian image installed.

Did you check to see if your device is supported yet? The device name should be specific for your screen, as listed in the fbtft file linked to in the beginning of the post

I too have a raspberry pi 2, and a waveshare spotpear 3.2 RPi lcd (v3) and I just can’t get it to work! I suspect I have a faulty LCD, but thought I’ll try this forum for help before I sent it back.

Soon as the pi is powered, the LCD lights up all white, with a few vertical pixels coloured at one of the edges, and nothing else. I don’t think that should happen – not at least before the BOIS has started up.

Anyway, point 1, says to change to dev/fb1 – I don’t have fb1. Only fb0 appears to be there. is that a clue what could be wrong? I have enabled SPI (is there a command to tell if its enabled?) I have also ran spidev to troubleshot (though I haven’t a clue what I means)

Any ideas what going wrong? I am using the latest “2015-02-16-raspbian-wheezy_zip”. Enabled SPI. done all the steps. Even changed mmcblk0p2 to mmcblk0p6 as suggested by Dabomber60 (but that freezes for me)

[ 0.000000] Linux version 3.18.5-v7+ (pi@raspi2) (gcc version 4.8.3 20140106 (prerelease) (crosstool-NG linaro-1.13.1-4.8-2014.01 – Linaro GCC 2013.11) ) #1 SMP PREEMPT Fri Feb 6 23:06:57 CET 2015

It seems all appears to be working – just the LCD is still all white with a single line of coloured pixels on edge) and nothing else. Is there a way to output, like jeff G script, of touch points?

I had the same one, I finally found a driver for it here: http://www.waveshare.net/wiki/3.2inch_RPi_LCD_(B) you will need to translate the page, but unpack the driver then run sudo ./LCD-show/LCD32-show. It should reboot and all will be good with the screen :)

Can anyone let me know if the default OS image sent with the screen works with pi2 or just Pi B/B+ as i think my screen maybe broken but can’t confirm it yet as i have not had it working at all

My system: Raspberry Pi 2 Model B with Raspian Wheezy from Febuary 2015. LCD display of Sainsmart 3.2 http://www.conrad.de/ce/de/product/1283498/Raspberry-Pi-Display-Modul-Touch-Display-81-cm-32/?ref=home&rt=home&rb=1

dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 cgroup_enable=memory elevator=deadline rootwait fbtft_device.custom fbtft_device.name=sainsmart32_spi fbtft_device.gpios=dc:24,reset:25 fbtft_device.bgr=1 fbtft_device.speed=48000000 fbcon=map:10 fbcon=font:ProFont6x11 logo.nologo dma.dmachans=0x7f35 console=tty1 consoleblank=0 fbtft_device.fps=50 fbtft_device.rotate=90

sainsmart32_spi width=320 height=240 buswidth=8 init=-1,0xCB,0x39,0x2C,0x00,0x34,0x02,-1,0xCF,0x00,0XC1,0X30,-1,0xE8,0x85,0x00,0x78,-1,0xEA,0x00,0x00,-1,0xED,0x64,0x03,0X12,0X81,-1,0xF7,0x20,-1,0xC0,0x23,-1,0xC1,0x10,-1,0xC5,0x3e,0x28,-1,0xC7,0x86,-1,0×36,0x28,-1,0x3A,0x55,-1,0xB1,0x00,0x18,-1,0xB6,0x08,0x82,0x27,-1,0xF2,0x00,-1,0×26,0x01,-1,0xE0,0x0F,0x31,0x2B,0x0C,0x0E,0x08,0x4E,0xF1,0x37,0x07,0x10,0x03,0x0E,0x09,0x00,-1,0XE1,0x00,0x0E,0x14,0x03,0x11,0x07,0x31,0xC1,0x48,0x08,0x0F,0x0C,0x31,0x36,0x0F,-1,0×11,-2,120,-1,0×29,-1,0x2c,-3

ads7846_device model=7846 cs=1 gpio_pendown=23 speed=2000000 keep_vref_on=1 swap_xy=1 pressure_max=255 x_plate_ohms=60 x_min=300 x_max=3800 y_min=700 y_max=3400

The LCD display shows the raspberry correctly. However, the touch screen input does not work. The mouse pointer can I move correctly with your finger, but I can not select things (function of the left mouse button).

Thank you so much for this great tutorial. I have my WaveShare SpotPear 3.2″ V4 working fine on my Raspberry Pi 2. If you are having problems with this specific hardware, skip step 5.

Can someone upload SD card image that works with RBP2 ? My idea is to use Eleduino TFT as additional screen and play movies via HDMI.. is it possible?

Do not follow this article when you don’t know what kind of LCD module. In my case, I follow all of this and my raspberry pi cannot boot anymore. I will try to recover, but I think I should format my SD card and reinstall OS.

Expecting this would builtin driver module within kernel and help with avoiding mistakenly overwriting anything. But with this is cause LCD screen to go blank white and no boot activity. Also noticed on HDMI it get stuck on Initial rainbow screen and stuck on that.

Also can you someone explain what exactly happen when do rpi-update? Want to understand what this step actualy doing and help me to debug any such situation and able to help others.

Does anyone tried splash boot screen with waveshare v4 LCD and Rpi2? I tried to follow some example from https://github.com/notro/fbtft/wiki/Bootsplash but no success.

Great tutorial thanks; got an X session working great 1st time. Has anybody managed to get Kodi/XMBC working on the LCD either Kodi standalone, Raspbmc or Xbian?

in the video you say to change the existing line to “snd-bcm2836” for the rasppi2 which isn’t listed in the written part of the instructions (part 4).. this should be added (I believe it caused me to have to re-image the OS again, the Pi wouldn’t boot to anything just using the written steps)

fbtft_device name=waveshare32b gpios=dc:22,reset:27 speed=48000000 width=320 height=240 buswidth=8 init=-1,0xCB,0x39,0x2C,0x00,0x34,0x02,-1,0xCF,0x00,0XC1,0X30,-1,0xE8,0x85,0x00,0x78,-1,0xEA,0x00,0x00,-1,0xED,0x64,0x03,0X12,0X81,-1,0xF7,0x20,-1,0xC0,0x23,-1,0xC1,0x10,-1,0xC5,0x3e,0x28,-1,0xC7,0x86,-1,0×36,0x28,-1,0x3A,0x55,-1,0xB1,0x00,0x18,-1,0xB6,0x08,0x82,0x27,-1,0xF2,0x00,-1,0×26,0x01,-1,0xE0,0x0F,0x31,0x2B,0x0C,0x0E,0x08,0x4E,0xF1,0x37,0x07,0x10,0x03,0x0E,0x09,0x00,-1,0XE1,0x00,0x0E,0x14,0x03,0x11,0x07,0x31,0xC1,0x48,0x08,0x0F,0x0C,0x31,0x36,0x0F,-1,0×11,-2,120,-1,0×29,-1,0x2c,-3

ads7846_device model=7846 cs=1 gpio_pendown=17 speed=1000000 keep_vref_on=1 swap_xy=0 pressure_max=255 x_plate_ohms=60 x_min=200 x_max=3900 y_min=200 y_max=3900

After following this tut to the letter on a brand new image of Raspian, I find that the touch driver does not function. Anyone experience the same? Basically all I did was image a current copy of rasping, did a apt-get upgrade, and then did this tutorial. Then the touch driver does not work, meaning the pointer does not respond.

The reason I did this was because on a production version of my system I added the 3.2 screen and it worked great except for the x-axis. So I wanted to see if there was something in my system that was interfering or if this is another error. Now with a raw rasping the driver does not work at all. I wonder if the touch pin has changed since the kernel is using BCM pins instead of GPIO pin numbers?

I have exactly the same problem. I also installed a new version of Raspbian, and the LCD part works fine (except all the windows are way too large), but the touch part doesn’t work at all… I’m using Waveshare Spotpear 3.2″ V4.

I remember that I plugged in the screen wrongly one time, before configuring any of the GPIO pins. Can this have damaged the screen? Still it’s weird that the display part works well and the touch part not at all.

I do not think that has anything to do with it. Other than power pins, the rest are communication. If it still works then you are good. No, there is something else. I do suspect it us related to the BCM pin numbering. The real question is… Why isnt the eeveloper responding? I have since abandoned this TFT because of his lack of response.

Touch actually goes through one of the SPI pins I think. Either the driver is toast with the required kernel update or the driver is using the wrong pin. It is very likely the this works well with previous raspian versions, but not with the new B+ and with the new kernel.

I am trying to use the sainsmart 2.8″ lcd sold through microcenter, using the sainsmart32_spi … seems to have the same pinouts, should I be able to get this to work? I am stuck at the white out screen on the lcd, doesn’t seem to recognize the module either.

Unfortunately I’ve tried that ( a few times actually) but the file still doesn’t exist. Thanks very much for the assistance anyway. I must be doing something wrong. My Raspian came from a Noobs installation, I’m wondering if I should try installing the OS from somewhere else. My LCD screen didn’t come with a CD or any docs so I’m completely in the dark here.

I have just found a way to get this file on my system! Apparently its part of the fbturbo installation. I found it here http://www.raspberrypi.org/forums/viewtopic.php?f=63&t=45746&start=75 (under experimental enhanced x driver (rpifb).. Sorry if this is obvious to everyone but I am SUCH a noob at this!!

Ok, what am I doing wrong. I am using a fresh install of the newest raspbian, on a Pi 2. After doing the first two steps and rebooting I get the rainbow screen, then the boot up process, and then my screen just goes black with a flashing cursor in the top left. I am not able to enter any commands or anything…like the pi is halting just after boot up. Any thoughts/suggestions would be greatly appreciated. Thanks.

Well figured out that step 1 was causing my problems. I’m guessing it is shutting off my hdmi feed and trying to switch it over to the SPI, am I guessing right? If so, not sure how I’m suppose to complete the rest of the steps if my hdmi output gets turned off before the LCD is actually set up to work…that sounds kind of smartass-like, which is not my intention, just looking for some clarification on what is going on in that first step as I am fairly new to this stuff. Thanks.

Anyway, I was able to do the rest of the steps with no problem. LCD didn’t work, but I am using a Waveshare 3.5, which doesn’t look to be supported yet. Mostly I am trying to play around and see if I can get it working somehow. Anyone found a way to do this yet?

I am having an issue with getting the GUI back. Every time I use startx my pi just sits there for about two minutes saying “No protocol specified”, and then it just gives up. I went through this tutorial about four times now and am not certain why it is doing this. I have the exact same LCD as is in the tutotial (WaveShare 3.2b). any help would be great.

Hi I am making a project for school,using the raspberry pi b+ and waveshare spotpare 3.2b. Everything works except the touch input doesn’t work. Any help would be appreciated very much.

Thanks for the tutorial. It works, but I get the boot/command line stuff on the HDMI monitor and the LCD only comes on when I do startx. Is there a way to get everything to appear on the LCD screen?

I am trying to get this same screen to work with the image of RetroPie 2.6 and it won’t work. I have followed all the steps and nothing, please help I an kinda a noob.

I have a Tontec 7 inch touchscreen with a Raspberry Pi 2 B. After following the instructions the touch screen is functioning but not properly… The only are that works is the upper left (and only a small area of that). I tried changing the width and height in the modules but it didnt change anything. Also the xy seems to be reversed, I changed the swap_xy to 1 but again no change on the screen.

Now the OS freezes at the emulation station loading screen, and if I connect my lcd it gives me a lot of error messages which I can only see on the 3.2 inch screen.

hi i have the same screen with a raspberry pi 2 im trying to run retro pie but it wont show ..however it shows all the commands …but i cant get it to show the gui …if u guys can make an image or something please i have been in this pain for two weeks already thank you

well ,,i follow all instructions and still kernel panic ,,,,may i request from mr. Circuitbasics@Gmail.Com that have a contact with manufacture and just ask for 2-3 links for image files for different versions of pi till all this f discussions are finished,,i cant understand 10 guys said we run it and 40 guys said kernel panic ,,as an expert i did 50 times imaging and follow all changes fro this forum and other forums and still cant run it ,,,so sth is wrong …..just asking the manufacture for simple f image ,,that`s it ,,,,simpleeeeeeeeeeeeeeeee

well i did it at last on pi 2,,after reading 100 pages and reimaging 50 times ,,i finally find the solution ,,,,there is a simple line forgotten to be attached in setup instruction,,,well i give u clue for prodigies ,,there is a step left between step 3 and 4,,,,and a simple change in step 5 according to your pi version ,,,that`s it ,,nothing else,,,,

Damn.. I thought I was kickin ass haha. I am using the SainSmart 3.2″.. the backlight is lit up and the pi was booting and everything just fine but on the final reboot it gets hung and says “nonblocking pool is initialized” ?? No idea what that means. But it’s def just frozen at this point.. on my main screen, and just the backlight is on the SainSmart.

This was an excellent tutorial. I have gotten an output to the screen, but no touchscreen usage . I have the Waveshare SpotPear 3.2 Inch LCD V4 screen, but using Raspberry PI 2 with wheezy. Any ideas?

Thanks a lot for this article. Very clear and easy . I am new in pi’s world and my 3.2″ screen is working fine. I rotate 90 º and works. I can use mouse and so on.Not problems.

I filed the steps to calibrate the screen but it did not work.I think because it did not find the TFT pin, because I think the touch problem is the assigned pin to control it changed.

I actually used the driver from here http://www.waveshare.com/wiki/3.2inch_RPi_LCD_(B) , from a new wheezy build, did nothing except enable SPI in config, install driver, and change mmcblk0p2 to mmcblk0p6 in cmdline.txt and it all worked, no drama.

Hi I managed to set up my touch screen ok but I now have the issue that everything desktop fits fine but the windows I open are all huge and I can’t remember how to change the size and cannot see the option in desktop preferences any idea what I have to do and is it at all possible to install kodi to run through the raspbian is as this would be a lot my useful than having to keep swapping os on every boot up many thanks in advanced hope you can help me

Advice to all who have the drivers from the (touch)screen manufacturer and cannot obtain those otherwise: you can skip everything and go to the update steps skipping the kernel and kernel modules update (as mentioned by the author) so that you don’t override the preinstalled drivers. I have a Waveshare 3.5″ RPi v3 (not the 3.2″ supported by notro’s drivers) and actually managed without any problems to get notro’s drivers make it work. However I am still reading about the xinput and xinput-calibrator to figure out how to include it as a kernel module so that I can compile my own kernel and add it there.

i have raspberry pi 2 with 3.2 inch rpi lcd v4 waveshare spotpear.i have done as per your instructions.the display is working but touch screen not working.error shows waveshare32b module not found as well as touch screen module not found messages.

Hey! i did this and rotated it… It loads console perfectly, but when it goes into startx, i get a black background with only the wastebin/trashcan… how do i get the taskbar(or whatever that bar is called)? and the raspberry background?

Unfortunately I have lost the Touch facility on my Waveshare 3.5″ LCD Touchscreen? Can you offer any reasons as to why? I copied the Raspbian image to my Raspberry Pi from the Waveshare website first of all. The Touchscreen displays but is not reactive with any touch

I have purchased a raspberry pi B+ total kit and waveshare 3.2 TFT display online. In the package i have been given a pre-loaded NOOBS installed SD card. I did not even start anything yet. What should i do what r the things needed and how to connect the display i really want to know. I need help as i don’t know anything. Does the above solution help or will u suggest something………………..

Hi great article thanks. I am trying to get a waveshare 7 inch LCD with capacitive touch running it works with the suppled image but if you upgrade it breaks the capacitive touch. I have a sense-hat and GPS which require the latest kernel and RASPIAN image and the install program for the screen replaces the /lib/modules directory and the kernel with older ones. I need to be able to install the touch drivers into a new clean OS can anyone give me some pointers? Thanks

For anyone who have those unbranded cheap TFT touch modules and cannot get it to work with this guide, I had success on my 3.5″ with the following steps: http://pastebin.com/89qmFbPB

I have the WaveShare 3.5 (A) and cannot get it to work with the Kali Linux with TFT for Raspberry Pi. Have anybody gotten the A to work? (Not the B, theres instructions for the B already and dont work with A)

So I have the original image that came with my screen and it works fine with the LCD but my problem is that I want to use my LCD screen with other distros (at this time I am trying to use it with Kali Linux with TFT support by default https://www.offensive-security.com/kali-linux-vmware-arm-image-download/) What do I have to do to transfer the needed files from the original image that WORKS with the screen and use them with another image?

I originally bought this bundle http://www.amazon.com/gp/product/B013E0IJUK?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00 with an RPi LCD V3 and no extra documentation on the specifics on the chipset. I tried with the bftft drivers but since I have no idea what to call this screen I just suppose it isn’t supported.

I’m not sure if the Jessie kernel is compatible – can anyone please confirm or not ?? Adafruit states that their setup for TFT screens are Wheezy only ; is this a different setup ??

I am using the same LCD and followed your tutorial. Have your tested the guide lately? Are you certain that it works? I see the boot messages on console but I get white screen as GUI starts.

Oct 16 17:38:48 spare kernel: [ 12.544859] graphics fb1: fb_ili9340 frame buffer, 320×240, 150 KiB video memory, 4 KiB DMA buffer memory, fps=50, spi0.0 at 48 MHz

After I rebooted in step 3, my raspberry pi won’t boot up again. It goes thru the process of booting and the text scrolls down and every thing says “ok”. Then instead of going to GUI it just guys to a black screen on my monitor with a blinking underscore in the top left corner. Anyway to get around this? or should I start over with a fresh disk image??

That is what happens to mine also.. So long story short —> THIS SITE NEEDS TO BE UPDATED OR SHUT DOWN <— There are a hundred people on here that have all lost everything on the pi drive, and spent all day (or more) working thru this tutorial 4 or 5 (dozen) times and nothing. Just have to reinstall the os over again and again.

Please check out my answer, it may help you if it works. I’m not in that case but I’m assuming that the desktop environment simply doesn’t automatically start running anymore… This can be changed in the raspi-setup

Try typing ‘startx’ if you problem isn’t solved (assuming you’re using Raspbian and LXDE), it should start the desktop environment you’re used to see. What you’re seeing is the Command Line Input interface (CLI), the most basic way to interact with a computer. Hope I helped you a little

I have tried to set up waveshare 32b on my Pi B using the latest Raspian download. I learned a lot in the process using Windows Putty, Nano etc. I have repeated the setup process several times from scratch and included the corrections for possible overwriting. My Waveshare SpotPear 3.2 inch RPi LCD V4 just shows a white screen. Any suggestions?

There was no disk included. I asked for drivers and was given a download link to the image file. After down loading this I tried it and still got just a white screen. The HDMI monitor locks partway though the boot. I can still log in to pi using putty from my PC.

Hi, I am using raspberry pi 2 with raspbian jessie installed. I the waveshare spotpear 3.2 v4. The above instructions are not working. and after completing the steps there was no display from hdmi or lcd. One things to notify is.: the etc/modules files only had i2c-dev and not snd-bcm2835.

I am trying to get this to work with Retro Pie 3.3.1 and the Waveshare3.2″ v4 but I only get the terminal on the lcd and emulation station starts on hdmi. to get it working with retro pie i just replaced startx with emulationstation. how do i get this to work?

Sir, Your post has very useful to me. i am using Tinylcd. but i cant get display. i am performing all the steps in your post. i cant get touch controller information from the product website and also i am using RASPberryPi B+ model. could u please give me best solution to my work. Than you.

what if OS is not Raspbian, any other distro like Yocto project, etc.? Could you please specify process without “rpi-update” that makes driver installation process more generic, not dedicated to Raspbian.

I completed all steps except for the last one (I want it to boot to console). However, when I reboot, it never completes the boot process. I start in recovery mode and check the cmdline.txt file and it is exactly how it appears on this page. I copied the kernel info as well, but I am not sure if it correct as I cannot get to it to check. Any suggestions? I might just reinstall the OS and start over…

i installed android OS in raspberry pi 2. can i use same LCD touch screen set up for android installed raspberry pi 2 which you are used for raspbian.

Is it normal the white back light during the whole process of initializing (I suspect that during the transportation trere is a deffect)? The problem is that I missed the step #1 and I performed it at the end. Unfortunately I don’t have any monitor available right now – neither “normal”, neither LCD :))))). Is it possible turning back the system or the only option is reinstallation of the Raspbian?

I have KeDei 3.5 inch TFT version 4.0 by Osoyoo. (released after January 1 2016) how do i get it working with vanilla Raspbian Jessie (do not want to install the image sent by the seller)

I’m trying to use an original Raspberry Pi model B with a cheap 3.5 inch 320×480 LCD which allegedly was manufactured to work with the Pi and has the correct fittings to fit over the GPIO pins. The operating system is the latest, downloaded yesterday and installed with NOOBS. I can’t get past step 2 of this guidance. When I reboot after using raspi-config I can see text generated as the Pi boots, then the HDMI fed screen goes blank apart from a flashing cursor in the top left hand corner. The LCD just remains white with nothing else on it. I have missed out step 1 and rebooted after step 2 and the screen functions as I would expect. Does anyone have any ideas please?

Thanks for the great tutorial. I do have a question. Once you install the drivers for the lcd are you effectively disabiling the hdmi port or is it still available to use and will the pi function with both displays. I have a pi 3

once you install the drivers it replaces the kernel by disabling hdmi output and enables it for LCD. i don’t think we have a solution to get em both working at the same time. ( you are encouraged to search for it )

Thanks for the guide, have been doing this with my son but once we leave raspi config and reboot all we get is a black screen with a flashing white horizontal line (dash). Can you help? I have looked in the comments at the end of the article but no one else appears to have this issue.

I have a raspberry pi 2 with waveshare screenn 3.5 inches. Isn’t it the same instructions. But it isnt working, all i get is a white screen, and the red led on the pi is on. The green LED isnot working.

My Rpi3 gets “ERROR: could not insert ‘spi_bcm2708’: No such device” after I enable SPI in the raspi-config.My Rpi3 is freezing on the rainbow screen after I reboot at the end of step 3. I’ve tried adding boot_delay=1 to config.txt.

if any interested, now i have a raspian image working on raspberry 3 with Waveshare 3.5, also with sdr support for dongles and FreqShow working perfectly on touch

ads7846_device model=7846 cs=1 gpio_pendown=17 speed=1000000 keep_vref_on=1 swap_xy=0 pressure_max=255 x_plate_ohms=60 x_min=200 x_max=3900 y_min=200 y_max=3900

No matter what I do, I can’t get this to work. It works perfectly fine on my Pi2, but when I follow and use the guide on my Zero, I always end up with the activity LED blinking 8 times (corrupt SD/filesystem error).

I’d like to find the driver software for my 7″ LCD with touch (official Pi unit) so that I can use it in buildroot. I wanted to make sure this kernel is the one before I started digging further.

I started through your tutorial and completed step 3 and rebooted. After the Raspberry screen and some of the boot text on my HDMI monitor, I now have a black HDMI monitor and a white screen on my LCD. Does this mean that the bootloader was overwritten or something else is wrong? How am I supposed to enter in the proposed fixes to the bootloader, when I can’t get the RPi to boot? Do I have to interrupt the boot process at some point to reinstall the bootloader or what?

Its a script. Download and instead of running sudo ./LCD4-show run cat ./LCD4-show to simply display what it does without actually running it. The commands are fairly simple modifying a few files. I actually saved the LCD-show.tar.gz on my own server for faster future download but also for backup as it saved me tons of hours (if that’s a measuring unit for time :) )

I used this link though (smaller file ~ 50 KB, fast download) http://www.waveshare.com/w/upload/4/4b/LCD-show-161112.tar.gz and replaced LCD4-show with LCD32-show in the last line.

I’m using RasPi Zero with latest (as of last week) Jessie Raspbian. Did you run the script? If it didn’t work and you have modified other files in the process of making it work, I would recommend installing a fresh installed image on a new card and running the script. Can you suspect the screen being faulty or got “burned” in the process?

i bought a 3.5 inch tft lcd screen from banggood. and i have installed raspian jessie, the latest version, in my sd card. but when i power on my Pi, only a white backlit screen comes. there are no images or graphics whatsoever.

The owner of this article should including a WARNING in the header that if someone follows the steps, they will install a deprecated driver (which is only visible as tiny text on its gethub page here https://github.com/notro/rpi-firmware). This driver after install will break Raspberry Pi and the SD card will need to be reimaged, for some less experienced users, this could also mean lost work if they failed to backup their code or resources. On windows, it requires installing Linux reader software and it takes a long time to fix this f**kup which could easily have been avoided if the author had and sense of responsibility.

I have done every thing right but the only major problem is that the screen is still white and my raspberrypi freezes after a line of code when booting up and I cant get in with SSH

Will your system work with my SainSmart 2.8″ 2.8 inch TFT LCD 240×320 Arduino DUE MEGA2560 R3 Raspberry Pi ? I would like to know before not be able to back out. Thanks, Lee

I know I will end up regretting this, but how do I change fb0 to fb1? I’m on the screen that has all the info, but no way to change it. Am I looking for a file? I have had my screen for MONTHS and I can’t do anything with my pi or the screen. I am >< close to smashing both. COMPLETE WASTE OF MONEY so far!!

hello. I really appreciate your blog post. I have a raspberry pi 3 B. I have been unable to get my waveshare 3.2 screen to work.I am at a complete loss for what to do. I do step 2 I change fb0 to fb1 and then follow your directions I don’t get the prompt to reboot; however, I do it manually with sudo reboot. that works fine then I complete step three and that works just fine; however once I reboot from getting those drivers and when I attempt to reboot it is unsuccessful and then my whole raspberry pi will not restart. then when I power it back on it will just shut back off. I then have to redo noobs onto a new SD card I would GREATLY appreciate anyones help

I ‘m actually using a LCD Waveshare3.2” , I followed your steps to setup the lcd touchscreen for my rpi and it work but I have a problem with the resolution because if I open a repertory I do not see the whole contents on the screen .

hi! thank you for this post…. I was wondering if all the raspberry pi’s gpio are being held by this screen or do we have any of those availables for use??

it worked. but the resolution is for bigger screens. i got the menubar small, but the rest appears too big , and out of screen. the wastebasket icon is 1/6 of my 3.2″ screen. wich HAS the resolution capability too display the whole desktop. But i’m a PI newby and dunno how to adjust the screen resolution on this display. anybody?

I did a 5inch LCD for my raspberry pi. I dont use the touchscreen so i didnt have to install any drivers. It works out of the box but doesnt cover the whole screen unless you open the terminal and do:

HI I have my RPI running Pi Presents on a view sonic TD2230 Touchscreen. It all works fine, touching the click areas can navigate you thru my presentation, The problem arises when you use multitouch gestures like you would on a iPhone. Pinch or expand etc… and then all touch ability goes away. I can still control the presentation via a mouse, but I don’t get touch control back until I either relaunch Pi Presents, or if I unplug and plug the usb cable going to the touchscreen.

Much of this is outdated on Raspbian Stretch where device tree overlays (see https://www.raspberrypi.org/documentation/configuration/device-tree.md) provide for most of the configuration automatically.

In the case of the WaveShare driver, their setup script from their “LCD_show” repository will copy a device-tree overlay to /boot/overlays/ that provides most of the module config etc via boot-time device-tree patch.

After I did the step that “INSTALL THE FBTFT DRIVERS” and then reboot, my raspberry pi couldn’t boot successfully and the green light is always on, could you help me solve this problem? Thank you.

Is this not the cutest, little display for the Raspberry Pi? It features a 3.5" display with 480x320 16-bit color pixels and a resistive touch overlay just like our popular original, but this one is engineered specifically to work with the newer "2x20 connector" Raspberry Pi"s. The plate uses the high speed SPI interface on the Pi and can use the mini display as a console, X window port, displaying images or video etc. Best of all it plugs right in on top!

This PiTFT 3.5" is designed to fit nicely onto the Raspberry Pi Zero, Pi 3, Pi 2 or Model A+ / B+(any Pi with a 2x20 connector). Not for use with an old Pi 1 with 2x13 connector If you"d like to use a 3.5" display with the original Pi A or Pi B, check out this version

The display uses the hardware SPI pins (SCK, MOSI, MISO, CE0, CE1) as well as GPIO #25 and #24. GPIO #18 can be used to PWM dim the backlight if you like. All other GPIO are unused. There"s a 2x13 "classic Pi" connection GPIO header on the bottom, you can connect a 26-pin Pi GPIO cable to it to use any of the other pins as you like. The other GPIO are broken out into solder pads at the bottom, in case you want to use more of the GPIO.

Best of all, it comes fully assembledand ready to plug into your Pi! You can use this as a display for running the X interface, or pygame. You can also have an HDMI display seperately connected. There"s four mounting ears that can be used to attach the display & Pi to a bezel, or snap them off with pliers (they"re perforated) for a slick exactly-the-same-size-as-a-Pi look.

We"ve created a custom kernel package based of off Notro"s awesome framebuffer work, so you can install it over your existing Raspbian (or derivative) images in just a few commands. Our tutorial shows you how to install the software, as well as calibrate the touchscreen, display images such as from your PiCam and more!

I just finished two solid days of work trying to get an HDMI LCD panel working with one of the inexpensive older model TFT LCD displays in a "Dual mode" configuration. There was a tremendous amount of help from this post, which got me most of the way there, but the infamous "last mile" still took me a while. I"m leaving some breadcrumbs here, as well as asking the group if anyone knows of a better way.

I am working on a device that uses a Raspberry Pi 4 as an embedded controller. For output, I need an 2K DSI LCD w/ its own HDMI adapter (Sharp LS055R1SX04, about $65 USD), as well as an inexpensive TFT LCD used for a basic touch user interface. The TFT LCD, which uses an ILI9341 LCD controller and an ads7846 touchscreen controller, can be had for about $10 USD. The Pi was flashed with the latest Raspberry Pi OS 32 bit then updated, so everything is current as of this writing (March 2021).

Initial configuration of the display worked with little issue. The HDMI adapter for the Sharp LCD works at 50 Hz only, so it requires custom timings. The TFT LCD uses the same controller chips as the original 3.5" Raspberry Pi LCD, so I was able to activate it with the rpi-display dtoverlay.

Booting with the above correctly revealed two framebuffer devices listed with ls -l /dev/fb*. The display initially showed as all white, then went all black, indicating correct initialization. However, when starting the desktop GUI, only the Sharp LCD showed any contents, and only it was listed as a device by xrandr.

The relevant X11 configuration files are located in /usr/share/X11/xorg.conf.d. The reference forum post mentioned replacing the contents of the file 99-fbturbo.conf. My first problem that took way to long to discover: 99-fbturbo.conf gets automatically deleted if the vc4-fkms-v3d overlay is activated (which is the default for a RasPi4). So, the configuration would work fine, but would suddenly stop working if the Pi is rebooted!

Based on claims of the above not being "ideal", I experimented with various settings. If the above file is deleted entirely, xrandr reports the Sharp LCD as the sole display. If you put the above file in place, and remove all references to the Sharp LCD (including the Device, Monitor, Screen, and ServerLayouts), xrandr correctly reports the TFT LCD, but not the Sharp LCD. I left JUST the Device sections in, but xrandr failed to correctly report one of the other.

No matter what combinations I tried, I was unable to get xrandr to list both the HDMI display and the SPI display at the same time. If all parts above ARE explicitly listed in the configuration, running xrandr reports an error that the RandR extension is not loaded. Thus I was unable to use the more advanced built in layout management of X11 using the RandR extension.

Simply using raspi-config"s System Options to boot to the Desktop works as expected, as my X11 configuration changed the last option in the "ServerFlags" section to:

Since xrandr was INOP in this configuration, I could not use xinput --map-to-output to limit touchscreen coordinates to the TFT LCD. Instead, I settled on using a combination of touch screen rotation, and input coordinate translation:

Note that the TransformationMatrix is very specific to a 1440x2560 in portrait mode with 320x240 in landscape mode to the right of the Sharp LCD. The numbers are basically:

My question to the group, if anyone knows, is simple: is it possible to configure a Pi4 so an SPI connected LCD can co-exist without disabling the RandR extension in X11?

My question to the group, if anyone knows, is simple: is it possible to configure a Pi4 so an SPI connected LCD can co-exist without disabling the RandR extension in X11?

With DRM/KMS X will render one "super desktop" covering all displays in their correct positions, and then tell each DRM/KMS device to display the correct bit of it. That"s how it works with dual HDMI on Pi4.

Now these SPI displays used to be driven by a driver that only exposed them as /dev/fbX nodes. They now appear to be under the tinydrm driver, so I would have expected them to show up as DRM/KMS devices. The output from modetest would be interesting to see (X can not be running when you run modetest). "xrandr --verbose" may tell you if you have vc4-(f)kms-v3d enabled. (Sorry, I don"t have one of these displays to test with)

If it is a DRM device, then I would expect X to be able to render to that as an alternate output device, providing it supports a suitable pixel format.

As I mentioned in my initial post, what "works" for me is the "rpi-display" overlay. If I execute fdtdump /boot/overlays/rpi-display.dtbo on my current configuration, I see this fragement:

I"m not real familiar with this stuff (I stumbled across it while I was stuck in the mud), but I assume by these results that there are two different drivers possible: fb_ili9341 which is the framebuffer version, and ili9341 which I assume is the DRM version. If I understand how this all fits together, it appears that when I select the "rpi-display" overlay, its picking the framebuffer version due to the last line in modules.alias?

Adding "tinydrm" to my google searches revealed this Github issue: https://github.com/notro/tinydrm/issues/14, and it mentions in passing "here is an example overlay source file", pointing to the rpi-display overlay. However, when I look at the referenced source, https://github.com/notro/tinydrm/blob/m ... verlay.dts, it contains this:

I suspect that perhaps my pins may not be set up correctly for those drivers? The overlay sources seemed to indicate they were the same, but I don"t know if that is true.

I"m not sure if I uncovered an inconsistency in what is supposed to be in the distribution, or if in order to get this to work, I need to download and compile the drivers? I"ll keep experimenting, but I wanted to report what I found thus far.

Switching to the "multi-inno,mi0283qt" compatible and I get nothing. Reading the DT bindings, the backlight has been moved from being a GPIO property of the display to being a link to the backlight device driver, so it"s understandable that the backlight stays off.

On my CM4 xrandr didn"t even list the extra SPI display, whereas on x86 it is listing all the connected and disconnected displays (7 of them total!). On both systems they show up under /sys/class/drm, so it may be the way that X enumerates the displays.

So, I tried the dtoverlay you posted, and sure enough - I was also able to get a test pattern using modetest! So, that explains part 1 - the pinout is different on some of these displays.

Next, I removed my previous 99-multihead-conf file from my "/usr/share/X11/xorg.conf.d/" and restarted the desktop manager. I opened a terminal window, entered "xrandr", and both displays listed! I thought it was solved, but at that point, my poor little Pi completely locked up. I had this same problem in the past when I was trying the various DRM driver overlays. The desktop just became very unstable.

Strange that the SPI display showed up for you but not me, even if it did then crash. I"ve tried an upgrade of my RaspiOS 32bit install (although with latest kernel) and it still doesn"t want to acknowledge the SPI display through xrandr. Could you post the output from xrandr when it sees both displays?

is needed for xrandr to see the display (listed as Unknown19-1 for me, presumably as X hasn"t been built with any knowledge of DRM_MODE_CONNECTOR_SPI being 19. https://elixir.bootlin.com/linux/latest ... ode.h#L390

However it is as I suspected - we have no mouse pointer on the TFT screen, presumably as X can"t cope with one display having a cursor plane and the other not. I don"t know the best way to overcome that.

*edit*: Minor correction there. If the two displays overlap, then the mouse cursor disappears on the SPI screen. If you set them to be independent (eg "xrandr --output Unknown19-1 --right-of HDMI-1"), then X switches mode and renders the mouse cursor.

Which sounds like yours (i.e the "Unknown19-1). I got the "lock up" again, but it turns out that lock-up was actually VNC (I"ve been using that to develop, as the text on a Sharp LCD is VERY tiny to look at in desktop mode). My console was still alive, so I hooked up an actual keyboard and mouse to the Pi, and the desktop on my Sharp LCD came alive. With the above two commands you"ve discovered, I now have two desktops. Sort of...

It appears as if the upper left hand corner of my Sharp LCD desktop is mirrored on the small LCD. It"s not two independent desktops. Instead, it"s the same desktop duplicated. I suspect that is probably more X configuration than driver stuff, however.

It appears as if the upper left hand corner of my Sharp LCD desktop is mirrored on the small LCD. It"s not two independent desktops. Instead, it"s the same desktop duplicated. I suspect that is probably more X configuration than driver stuff, however.

In these videos, the SPI (GPIO) bus is referred to being the bottleneck. SPI based displays update over a serial data bus, transmitting one bit per clock cycle on the bus. A 320x240x16bpp display hence requires a SPI bus clock rate of 73.728MHz to achieve a full 60fps refresh frequency. Not many SPI LCD controllers can communicate this fast in practice, but are constrained to e.g. a 16-50MHz SPI bus clock speed, capping the maximum update rate significantly. Can we do anything about this?

The fbcp-ili9341 project started out as a display driver for the Adafruit 2.8" 320x240 TFT w/ Touch screen for Raspberry Pi display that utilizes the ILI9341 controller. On that display, fbcp-ili9341 can achieve a 60fps update rate, depending on the content that is being displayed. Check out these videos for examples of the driver in action:

Given that the SPI bus can be so constrained on bandwidth, how come fbcp-ili9341 seems to be able to update at up to 60fps? The way this is achieved is by what could be called adaptive display stream updates. Instead of uploading each pixel at each display refresh cycle, only the actually changed pixels on screen are submitted to the display. This is doable because the ILI9341 controller, as many other popular controllers, have communication interface functions that allow specifying partial screen updates, down to subrectangles or even individual pixel levels. This allows beating the bandwidth limit: for example in Quake, even though it is a fast pacing game, on average only about 46% of all pixels on screen change each rendered frame. Some parts, such as the UI stay practically constant across multiple frames.

A hybrid of both Polled Mode SPI and DMA based transfers are utilized. Long sequential transfer bursts are performed using DMA, and when DMA would have too much latency, Polled Mode SPI is applied instead.

Undocumented BCM2835 features are used to squeeze out maximum bandwidth: SPI CDIV is driven at even numbers (and not just powers of two), and the SPI DLEN register is forced in non-DMA mode to avoid an idle 9th clock cycle for each transferred byte.

Good old interlacing is added into the mix: if the amount of pixels that needs updating is detected to be too much that the SPI bus cannot handle it, the driver adaptively resorts to doing an interlaced update, uploading even and odd scanlines at subsequent frames. Once the number of pending pixels to write returns to manageable amounts, progressive updating is resumed. This effectively doubles the maximum display update rate. (If you do not like the visual appearance that interlacing causes, it is easy to disable this by uncommenting the line #define NO_INTERLACING in file config.h)

A number of other micro-optimization techniques are used, such as batch updating rectangular spans of pixels, merging disjoint-but-close spans of pixels on the same scanline, and latching Column and Page End Addresses to bottom-right corner of the display to be able to cut CASET and PASET messages in mid-communication.

The result is that the SPI bus can be kept close to 100% saturation, ~94-97% usual, to maximize the utilization rate of the bus, while only transmitting practically the minimum number of bytes needed to describe each new frame.

although not all boards are actively tested on, so ymmv especially on older boards. (Bug fixes welcome, use https://elinux.org/RPi_HardwareHistory to identify which board you are running on)

This driver does not utilize the notro/fbtft framebuffer driver, so that needs to be disabled if active. That is, if your /boot/config.txt file has lines that look something like dtoverlay=pitft28r, ..., dtoverlay=waveshare32b, ... or dtoverlay=flexfb, ..., those should be removed.

This program neither utilizes the default SPI driver, so a line such as dtparam=spi=on in /boot/config.txt should also be removed so that it will not cause conflicts.

When using one of the displays that stack on top of the Pi that are already recognized by fbcp-ili9341, you don"t need to specify the GPIO pin assignments, but fbcp-ili9341 code already has those. Pass one of the following CMake directives for the hats:

-DFREEPLAYTECH_WAVESHARE32B=ON: If you are running on the Freeplay CM3 or Zero device, pass this flag. (this is not a hat, but still a preconfigured pin assignment)

-DPIRATE_AUDIO_ST7789_HAT=ON: If specified, targets a Pirate Audio 240x240, 1.3inch IPS LCD display HAT for Raspberry Pi with ST7789 display controller

-DKEDEI_V63_MPI3501=ON: If specified, targets a KeDei 3.5 inch SPI TFTLCD 480*320 16bit/18bit version 6.3 2018/4/9 display with MPI3501 display controller.

If you connected wires directly on the Pi instead of using a Hat from the above list, you will need to use the configuration directives below. In addition to specifying the display, you will also need to tell fbcp-ili9341 which GPIO pins you wired the connections to. To configure the display controller, pass one of:

-DGPIO_TFT_DATA_CONTROL=number: Specifies/overrides which GPIO pin to use for the Data/Control (DC) line on the 4-wire SPI communication. This pin number is specified in BCM pin numbers. If you have a 3-wire SPI display that does not have a Data/Control line, set this value to -1, i.e. -DGPIO_TFT_DATA_CONTROL=-1 to tell fbcp-ili9341 to target 3-wire ("9-bit") SPI communication.

-DGPIO_TFT_RESET_PIN=number: Specifies/overrides which GPIO pin to use for the display Reset line. This pin number is specified in BCM pin numbers. If omitted, it is assumed that the display does not have a Reset pin, and is always on.

-DGPIO_TFT_BACKLIGHT=number: Specifies/overrides which GPIO pin to use for the display backlight line. This pin number is specified in BCM pin numbers. If omitted, it is assumed that the display does not have a GPIO-controlled backlight pin, and is always on. If setting this, also see the #define BACKLIGHT_CONTROL option in config.h.

fbcp-ili9341 always uses the hardware SPI0 port, so the MISO, MOSI, CLK and CE0 pins are always the same and cannot be changed. The MISO pin is actually not used (at the moment at least), so you can just skip connecting that one. If your display is a rogue one that ignores the chip enable line, you can omit connecting that as well, or might also be able to get away by connecting that to ground if you are hard pressed to simplify wiring (depending on the display).

-DSPI_BUS_CLOCK_DIVISOR=even_number: Sets the clock divisor number which along with the Pi core_freq= option in /boot/config.txt specifies the overall speed that the display SPI communication bus is driven at. SPI_frequency = core_freq/divisor. SPI_BUS_CLOCK_DIVISOR must be an even number. Default Pi 3B and Zero W core_freq is 400MHz, and generally a value -DSPI_BUS_CLOCK_DIVISOR=6 seems to be the best that a ILI9341 display can do. Try a larger value if the display shows corrupt output, or a smaller value to get higher bandwidth. See ili9341.h and waveshare35b.h for data points on tuning the maximum SPI performance. Safe initial value could be something like -DSPI_BUS_CLOCK_DIVISOR=30.

There are a couple of options to explicitly say which Pi board you want to target. These should be autodetected for you and generally are not needed, but e.g. if you are cross compiling for another Pi board from another system, or want to be explicit, you can try:

-DSINGLE_CORE_BOARD=ON: Pass this option if you are running on a Pi that has only one hardware thread (Pi Model A, Pi Model B, Compute Module 1, Pi Zero/Zero W). If not present, autodetected.

-DARMV8A=ON: Pass this option to specifically optimize for ARMv8-A instruction set (Pi 2B >= rev. 1.2, 3B, 3B+, CM3, CM3 lite, 4B, CM4, Pi400). If not present, autodetected.

-DBACKLIGHT_CONTROL=ON: If set, enables fbcp-ili9341 to control the display backlight in the given backlight pin. The display will go to sleep after a period of inactivity on the screen. If not, backlight is not touched.

-DDISPLAY_CROPPED_INSTEAD_OF_SCALING=ON: If set, and source video frame is larger than the SPI display video resolution, the source video is presented on the SPI display by cropping out parts of it in all directions, instead of scaling to fit.

-DDISPLAY_BREAK_ASPECT_RATIO_WHEN_SCALING=ON: When scaling source video to SPI display, scaling is performed by default following aspect ratio, adding letterboxes/pillarboxes as needed. If this is set, the stretching is performed breaking aspect