Difference between revisions of "EBC Exercise 12a 2.4 TFT LCD display via SPI"

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m (tinyDRM)
 
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== tinyDRM ==
 
  
The tinyDRM driver requires a 4.19 kernel or newer.  Run '''uname -a''' to see which kernel is being run.
+
This table shows how to wire the LCD display for SPI 1.
If it isn't new enough run:
 
  
bone$ '''cd /opt/scripts/tools'''
+
{| class="wikitable"
bone$ '''sudo ./update_kernel.sh --lts-4_19'''
+
|-
bone$ '''reboot'''
+
! LCD !! Bone
 +
|-
 +
| MISO    || P9_29
 +
|-
 +
| LED    || P9_16
 +
|-
 +
| SCK    || P9_31
 +
|-
 +
| MOSI    || P9_30
 +
|-
 +
| D/C    || P9_27
 +
|-
 +
| RESET  || P9_25
 +
|-
 +
| CS      || P9_28
 +
|-
 +
| GND    || P9_2
 +
|-
 +
| VCC    || P9_4
 +
|}
  
Clone the course repo.
+
== tinyDRM ==
  
  bone$ '''git clone https://github.com/MarkAYoder/BeagleBoard-exercises.git exercises'''
+
The tinyDRM driver requires a 4.19 kernel or newer. Run '''uname -a''' to see which kernel is being run.
 +
If it isn't new enough update it.
  
and then
+
Add uboot_overlay_addr4=BB-LCD-ADAFRUIT-24-SPI'''1'''-00A0.dtbo to /boot/uEnv.txt if you are using SPI1.
  
bone$ '''cd exercises/display/ili9341'''
+
Edit '''/boot/uEnv.txt''' and find the line starting with
  bone$ '''git pull'''
+
  #uboot_overlay_addr4=
  bone$ '''cd tinyDRM'''
+
Uncomment it and change it to:
  bone$ '''ls'''
+
  uboot_overlay_addr4=/lib/firmware/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo
  BB-LCD-ADAFRUIT-24-SPI1-00A0.dts install.sh  Makefile
+
Next, verify the file is there.
 +
  bone$ '''ls -ls /lib/firmware/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo'''
 +
  4 -rw-r--r-- 1 root root 3606 Aug 21  2021 /lib/firmware/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo
 +
If the file is not there, follow the instructions in the next section. If the file is there,
 +
skip to the '''Using the LCD display''' section.
  
'''BB-LCD-ADAFRUIT-24-SPI1-00A0.dts''' is the device driver for the LCD attached to SPI 1. It also assumes the backlight is attached to '''P9_14''' (not P9_16 as in the table above.).
+
=== Compiling and installing BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo ===
 +
Do this if BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo isn't there.
 +
bone$ '''cd /opt/source/dtb-5.10-ti'''
 +
bone$ '''make'''
 +
This will take a while, then:
 +
bone$ '''cp src/arm/overlays/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtb0 /lib/firmware'''
 +
Now you should be ready to use the display.
  
To compile it:
+
=== Using the LCD display ===
bone$ '''make'''
 
cpp -x assembler-with-cpp -nostdinc -I /opt/source/dtb-4.19-ti/include -undef -D__DTS__ < BB-LCD-ADAFRUIT-24-SPI1-00A0.dts | dtc -i /opt/source/dtb-4.19-ti/include -I dts -O dtb -b 0 -o BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo -
 
BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo: Warning (chosen_node_is_root): /fragment@0/__overlay__/chosen: chosen node must be at root nod
 
bone$ '''make install'''
 
sudo cp --backup BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo /lib/firmware
 
Add uboot_overlay_addr4=/lib/firmware/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo to /boot/uEnv.txt
 
  
Now, follow the instructions from the Makefile and edit '''/boot/uEnv.txt''' and find the line starting with
+
Reboot and check for '''/dev/fb0'''
#uboot_overlay_addr4=/lib/firmware
 
Uncomment it and change it to:
 
uboot_overlay_addr4=/lib/firmware/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo
 
The reboot and check of '''/dev/fb0'''
 
 
  bone$ '''sudo reboot'''
 
  bone$ '''sudo reboot'''
 
After rebooting...
 
After rebooting...
 
  bone$ ls -ls /dev/fb0
 
  bone$ ls -ls /dev/fb0
 
  0 crw-rw---- 1 root video 29, 0 Oct  3 10:07 /dev/fb0
 
  0 crw-rw---- 1 root video 29, 0 Oct  3 10:07 /dev/fb0
 +
 +
The LCD should be showing some text.
  
 
You can control the backlight with:
 
You can control the backlight with:
  bone$ '''cd /sys/devices/platform/backlight_pwm/backlight/backlight_pwm'''
+
  bone$ '''cd /sys/class/backlight/backlight_pwm'''
bone$ '''sudo chgrp debian *'''                       
+
Turn the display off, then on with: (Yup, it's backwards.)
bone$ '''sudo chmod g+w *'''
 
Turn the display off, then on with:
 
 
  bone$ '''echo 1 > bl_power'''                         
 
  bone$ '''echo 1 > bl_power'''                         
 
  bone$ '''echo 0 > bl_power'''
 
  bone$ '''echo 0 > bl_power'''
Line 86: Line 104:
 
  bone$ '''echo 25 > brightness'''
 
  bone$ '''echo 25 > brightness'''
  
Now jump to the software section to see how to display images.
+
Now jump to the Using the Frame Buffer section to see how to display images, etc..
 
 
== Legacy fbtft ==
 
 
 
Clone the course repo.
 
 
 
bone$ '''git clone https://github.com/MarkAYoder/BeagleBoard-exercises.git exercises'''
 
 
 
and then
 
 
 
bone$ '''cd exercises/display/ili9341/fb'''
 
bone$ '''git pull'''
 
bone$ '''./on.sh'''
 
 
 
After a moment the display should turn dark.  Look in '''on.sh''' to see what it did.
 
If the display doesn't turn on, look in '''on.sh''' and make sure it's set for the correct SPI bus.
 
  
 
== Using the framebuffer ==
 
== Using the framebuffer ==
Line 110: Line 113:
 
  bone$ '''sudo apt install fbi'''
 
  bone$ '''sudo apt install fbi'''
 
Display them with:
 
Display them with:
  bone$ '''fbi -noverbose -T 1 -a boris.png'''
+
  bone$ '''sudo fbi -noverbose -T 1 -a boris.png'''
 
You should now see Boris the Beagle on your display.
 
You should now see Boris the Beagle on your display.
  
Line 116: Line 119:
 
Install '''mplayer''' and load a movie on the Bone (see install.sh).   
 
Install '''mplayer''' and load a movie on the Bone (see install.sh).   
 
  bone$ '''sudo apt install mplayer'''
 
  bone$ '''sudo apt install mplayer'''
 +
Get something to play
 +
bone$ '''wget http://hubblesource.stsci.edu/sources/video/clips/details/images/hst_1.mpg'''
 +
And play it
 +
bone$ '''mplayer -vo fbdev2 -nolirc -framedrop hst_1.mpg'''
 +
 +
If you get an error you might need:
 +
bone$ '''export SDL_VIDEODRIVER=fbcon'''
 +
bone$ '''export SDL_FBDEV=/dev/fb0'''
  
 
Play the movie.  Rotate the movie.
 
Play the movie.  Rotate the movie.
Line 140: Line 151:
 
   
 
   
 
  sudo fbi -noverbose -T 1 $TMP_FILE
 
  sudo fbi -noverbose -T 1 $TMP_FILE
 +
 +
=== pygame ===
 +
It's  not hard to get pygame to display on the LCD.
 +
 +
bone$ '''sudo apt install python3-pygame'''
 +
bone$ '''cd exercises/displays/ili9341/pygame'''
 +
bone$ '''sudo ./clock.py'''
 +
 +
Look in '''clock.py''' to see how to direct the graphics to the LCD.
 +
 +
== fbtft ==
 +
 +
fbtft is no longer supported after the 5.4 kernel.
 +
(https://github.com/notro/fbtft/wiki#fbtft_device-and-flexfb-are-gone-in-54)
 +
 +
Clone the course repo.
 +
 +
bone$ '''git clone https://github.com/MarkAYoder/BeagleBoard-exercises.git exercises'''
 +
 +
and then
 +
 +
bone$ '''cd exercises/display/ili9341/fb'''
 +
bone$ '''git pull'''
 +
bone$ '''./on.sh'''
 +
 +
After a moment the display should turn dark.  Look in '''on.sh''' to see what it did.
 +
If the display doesn't turn on, look in '''on.sh''' and make sure it's set for the correct SPI bus.
  
 
{{YoderFoot}}
 
{{YoderFoot}}

Latest revision as of 08:59, 9 January 2024

thumb‎ Embedded Linux Class by Mark A. Yoder


2.4" TFT LCD

This is an exercise in interfacing the 2.4" TFT LCD display (ili9341) via a SPI bus. The newer using the tinyDRM driver and the older uses fbtft.

The Hardware

This table shows how to wire the LCD display for SPI 0.

LCD Bone
MISO P9_21
LED P9_16
SCK P9_22
MOSI P9_18
D/C P9_19
RESET P9_20
CS P9_17
GND P9_2
VCC P9_4


This table shows how to wire the LCD display for SPI 1.

LCD Bone
MISO P9_29
LED P9_16
SCK P9_31
MOSI P9_30
D/C P9_27
RESET P9_25
CS P9_28
GND P9_2
VCC P9_4

tinyDRM

The tinyDRM driver requires a 4.19 kernel or newer. Run uname -a to see which kernel is being run. If it isn't new enough update it.

Add uboot_overlay_addr4=BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo to /boot/uEnv.txt if you are using SPI1.

Edit /boot/uEnv.txt and find the line starting with

#uboot_overlay_addr4=

Uncomment it and change it to:

uboot_overlay_addr4=/lib/firmware/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo

Next, verify the file is there.

bone$ ls -ls /lib/firmware/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo
4 -rw-r--r-- 1 root root 3606 Aug 21  2021 /lib/firmware/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo

If the file is not there, follow the instructions in the next section. If the file is there, skip to the Using the LCD display section.

Compiling and installing BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo

Do this if BB-LCD-ADAFRUIT-24-SPI1-00A0.dtbo isn't there.

bone$ cd /opt/source/dtb-5.10-ti
bone$ make

This will take a while, then:

bone$ cp src/arm/overlays/BB-LCD-ADAFRUIT-24-SPI1-00A0.dtb0 /lib/firmware

Now you should be ready to use the display.

Using the LCD display

Reboot and check for /dev/fb0

bone$ sudo reboot

After rebooting...

bone$ ls -ls /dev/fb0
0 crw-rw---- 1 root video 29, 0 Oct  3 10:07 /dev/fb0

The LCD should be showing some text.

You can control the backlight with:

bone$ cd /sys/class/backlight/backlight_pwm

Turn the display off, then on with: (Yup, it's backwards.)

bone$ echo 1 > bl_power                        
bone$ echo 0 > bl_power

Change the brightness to 25% with:

bone$ echo 25 > brightness

Now jump to the Using the Frame Buffer section to see how to display images, etc..

Using the framebuffer

Displaying Images

Follow the instructions in install.sh to download fbi and some images.

bone$ sudo apt update
bone$ sudo apt install fbi

Display them with:

bone$ sudo fbi -noverbose -T 1 -a boris.png

You should now see Boris the Beagle on your display.

Playing Movies

Install mplayer and load a movie on the Bone (see install.sh).

bone$ sudo apt install mplayer

Get something to play

bone$ wget http://hubblesource.stsci.edu/sources/video/clips/details/images/hst_1.mpg

And play it

bone$ mplayer -vo fbdev2 -nolirc -framedrop hst_1.mpg

If you get an error you might need:

bone$ export SDL_VIDEODRIVER=fbcon 
bone$ export SDL_FBDEV=/dev/fb0

Play the movie. Rotate the movie.

Generate Text

Install imagemagick.

bone$ sudo apt install imagemagick

See text.sh for an example of using imagemagick to write text to the LCD display. Write your name on the LCD. Display an image and write some text on it.

# Here's how to use imagemagick to display text
# Make a blank image
SIZE=320x240
TMP_FILE=/tmp/frame.png

# From: http://www.imagemagick.org/Usage/text/
convert -background lightblue -fill blue -font Times-Roman -pointsize 24 \
     -size $SIZE \
     label:'ImageMagick\nExamples\nby Anthony' \
     -draw "text 0,200 'Bottom of Display'" \
     $TMP_FILE

sudo fbi -noverbose -T 1 $TMP_FILE

pygame

It's not hard to get pygame to display on the LCD.

bone$ sudo apt install python3-pygame
bone$ cd exercises/displays/ili9341/pygame
bone$ sudo ./clock.py

Look in clock.py to see how to direct the graphics to the LCD.

fbtft

fbtft is no longer supported after the 5.4 kernel. (https://github.com/notro/fbtft/wiki#fbtft_device-and-flexfb-are-gone-in-54)

Clone the course repo.

bone$ git clone https://github.com/MarkAYoder/BeagleBoard-exercises.git exercises

and then

bone$ cd exercises/display/ili9341/fb
bone$ git pull
bone$ ./on.sh

After a moment the display should turn dark. Look in on.sh to see what it did. If the display doesn't turn on, look in on.sh and make sure it's set for the correct SPI bus.




thumb‎ Embedded Linux Class by Mark A. Yoder