5 Inch TFT DPI display issue with RPI4B

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paschpau
 
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Joined: Sat Nov 14, 2020 1:46 am

5 Inch TFT DPI display issue with RPI4B

Post by paschpau »

Greetings Everyone,

I am new to the forums so if this posting is in the wrong area, apologies in advance.

I am currently working on a project that utilizes a Raspberry Pi 4B 4GB, an Adafruit 5-inch TFT LCD (ID: 1680), and an Adafruit 40 TFT Friend (ID: 1932). Using a 15 Watt (5V, 3A) wall wart to power everything.

I am running into an issue where the colors / display on the LCD are not displaying correctly. It looks like there is no red (see attached image). I have attached a picture of a raspi-gpio get to show that my GPIO are set the appropriate alt function (this was the same across all versions of Raspbian I tried). I used this website (https://pinout.xyz/), along with official RPI documentation to wire up the RPI and TFT breakout. I have also tested the continuity of all my wires from the RPI GPIO to the TFT breakout, all seems good there.

Here is my config.txt:

Code: Select all

# For more options and information see
# http://rpf.io/configtxt
# Some settings may impact device functionality. See link above for details

# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1

# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
#disable_overscan=1

# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
#overscan_left=16
#overscan_right=16
#overscan_top=16
#overscan_bottom=16

# uncomment to force a console size. By default it will be display's size minus
# overscan.
#framebuffer_width=1280
#framebuffer_height=720

# uncomment if hdmi display is not detected and composite is being output
#hdmi_force_hotplug=1

# uncomment to force a specific HDMI mode (this will force VGA)
#hdmi_group=1
#hdmi_mode=1

# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
#hdmi_drive=2

# uncomment to increase signal to HDMI, if you have interference, blanking, or
# no display
#config_hdmi_boost=4

# uncomment for composite PAL
#sdtv_mode=2

#uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

# Uncomment this to enable infrared communication.
#dtoverlay=gpio-ir,gpio_pin=17
#dtoverlay=gpio-ir-tx,gpio_pin=18

# Additional overlays and parameters are documented /boot/overlays/README

# Enable audio (loads snd_bcm2835)
dtparam=audio=on

# Disable spi and i2c, we need these pins.
dtparam=spi=off
dtparam=i2c_arm=off

# Set screen size and any overscan required
overscan_left=0
overscan_right=0
overscan_top=0
overscan_bottom=0
framebuffer_width=800
framebuffer_height=480

# enable the DPI display
enable_dpi_lcd=1
display_default_lcd=1

# Enable DPI overlay
dtoverlay=dpi24

# set up the size to 800x480
dpi_group=2
dpi_mode=87

# set up the hsync/vsync/clock polarity and format
dpi_output_format=454661

# set up the size to 800x480
hdmi_timings=800 0 40 48 88 480 0 13 3 32 0 0 0 60 0 32000000 6
I have tried 2 different Raspbian releases so far (Buster (2021-05-07), and Bullseye (2021-10-30). Both have the same problem with the display.

Any help/tips would be greatly appreciated. Thank you
Attachments
GPIO GET 2.PNG
GPIO GET 2.PNG (41.5 KiB) Viewed 336 times
Display Issue-min.PNG
Display Issue-min.PNG (379.4 KiB) Viewed 338 times
Connection-min.PNG
Connection-min.PNG (223.71 KiB) Viewed 338 times

User avatar
paschpau
 
Posts: 2
Joined: Sat Nov 14, 2020 1:46 am

Re: 5 Inch TFT DPI display issue with RPI4B

Post by paschpau »

Update!

After doing some adjusting on the dpi_output_format magic number I was able to get the display looking good.

For anyone that is stuck in my same shoes I changed the dpi_output_format value from 0x6f005 to 0x6f007.

I am unsure why I needed to change this number, I recognize that it configures certain things regarding the output signal (RGB Order, Pixel Clock, SYNC invert, SYNC phase, etc.). I am just unsure what it changed as I am not too familiar with editing the value. If anyone could explain why this change fixed the issue I would appreciate it greatly!

Thank you.

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