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BeagleBone Black: build fbtft drivers for latest Linux 3.8 kernel

Use small TFT LCDs displays as Linux framebuffer on BeagleBone Black using fbtft drivers for Linux 3.8 kernel

bbb1.jpg

My previous post showed how to use small TFT LCDs as a Linux framebuffer on a BeagleBone Black:

I showed how to use pre-built fbtft kernel modules to provide the necessary Linux device driver.  However, what if you want to use fbtft modules with a newer version of the Linux kernel?

 

The BeagleBone Black currently ships with a Linux 3.8 kernel built from Robert C. Nelson's am33x-v3.8 branch.  I do also have fbtft working on the BBB with newer kernels such as TI's 4.1 branch and mainline 4.4-rc1, but I will focus on Linux 3.8 for this post.

 

Here is how I built FBTFT for Linux 3.8.13-bone79 kernel:

(for my complete transcript see this GitHub Gist)

 

Step 1: Clone repo & checkout branch

Clone bb-kernel repo & checkout am33x-v3.8 branch

$ git clone https://github.com/RobertCNelson/bb-kernel

 

$ cd bb-kernel

 

$ git checkout am33x-v3.8

Already on 'am33x-v3.8'

Your branch is up-to-date with 'origin/am33x-v3.8'.

 

Step 2: Run build script

Move into the new branch directory & run the build kernel script:

$ ./build_kernel.sh

 

-----------------------------

make -j4 ARCH=arm LOCALVERSION=-bone79 CROSS_COMPILE="ccache /home/afustini/dev/bbb/bb-kernel/dl/gcc-linaro-arm-linux-gnueabihf-4.7-2013.04-20130415_linux/bin/arm-linux-gnueabihf-" dtbs

-----------------------------

 

Script Complete

 

Step 3: Add fbtft drivers

Add fbtft drivers into Linux kernel source based on instructions from fbtft README.

 

From within the bb-kernel dir:

$ cd KERNEL/drivers/video

 

 

$ git clone https://github.com/notro/fbtft

Cloning into 'fbtft'...

remote: Counting objects: 1170, done.

remote: Total 1170 (delta 0), reused 0 (delta 0), pack-reused 1170

Receiving objects: 100% (1170/1170), 526.16 KiB | 0 bytes/s, done.

Resolving deltas: 100% (726/726), done.

Checking connectivity... done.

 

Add to KERNEL/drivers/video/Kconfig:

source "drivers/video/fbtft/Kconfig"

 

Add to KERNEL/drivers/video/Makefile:

obj-y += fbtft/

 

Verify files were modified correctly

$ git diff

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig

index a0c757a..50c5d62 100644

--- a/drivers/video/Kconfig

+++ b/drivers/video/Kconfig

@@ -2494,4 +2494,6 @@ config FB_SSD1307

  This driver implements support for the Solomon SSD1307

  OLED controller over I2C.

 

+source "drivers/video/fbtft/Kconfig"

+

endmenu

diff --git a/drivers/video/Makefile b/drivers/video/Makefile

index 28bfbca..6bd03af 100644

--- a/drivers/video/Makefile

+++ b/drivers/video/Makefile

@@ -174,3 +174,6 @@ obj-$(CONFIG_DISPLAY_TIMING) += display_timing.o

obj-$(CONFIG_OF_DISPLAY_TIMING) += of_display_timing.o

obj-$(CONFIG_VIDEOMODE) += videomode.o

obj-$(CONFIG_OF_VIDEOMODE) += of_videomode.o

+

+obj-y += fbtft/

+

 

Step 4: Rebuild kernel

Now run the rebuild script to compile the fbtft modules:

$ ./tools/rebuild.sh

+ Detected build host ["Fedora release 22 (Twenty Two)"]

+ host: [x86_64]

+ git HEAD commit: [a50680ea2cc2fc4519353dee4c1cbb47e475d8b2]

 

 

The kernel config menu should appear shortly after starting the rebuild script.  Follow these screenshots to select the fbtft drivers:

step1.png

step2.png

step3.png

test4.png

After exit the kernel config menu, the rebuild script should continue:

‘.config’ -> ‘/home/afustini/dev/bbb/bb-kernel/patches/defconfig’

-----------------------------

make -j4 ARCH=arm LOCALVERSION=-bone79 CROSS_COMPILE="ccache /home/afustini/dev/bbb/bb-kernel/dl/gcc-linaro-arm-linux-gnueabihf-4.7-2013.04-20130415_linux/bin/arm-linux-gnueabihf-" zImage modules

-----------------------------

scripts/kconfig/conf --silentoldconfig Kconfig

 

Script Complete

 

Verify in bb-kernel dir that fbtft modules were compiled:

$ find |grep fbtft |grep ko$

./KERNEL/drivers/video/fbtft/fb_upd161704.ko

./KERNEL/drivers/video/fbtft/fb_ili9486.ko

 

./KERNEL/drivers/video/fbtft/fb_pcd8544.ko

./KERNEL/drivers/video/fbtft/fb_tls8204.ko

 

Verify in bb-kernel/deploy that kernel and tarballs were created

$ ls -ltar deploy/

-rwxrwxr-x 1 afustini afustini 5552136 Oct 31 13:01 3.8.13-bone79.zImage

-rw-rw-r-- 1 afustini afustini 110207 Oct 31 13:01 config-3.8.13-bone79

-rw-rw-r-- 1 afustini afustini 11690719 Oct 31 13:01 3.8.13-bone79-modules.tar.gz

-rw-rw-r-- 1 afustini afustini 1263879 Oct 31 13:01 3.8.13-bone79-firmware.tar.gz

-rw-rw-r-- 1 afustini afustini 39642 Oct 31 13:01 3.8.13-bone79-dtbs.tar.gz

 

Step 5: Install new kernel on SD Card (from Linux host)

My SD card already had been imaged with:

 

From within bb-kernel dir

$ sudo ./tools/install_kernel.sh

ERROR: MMC is not defined in system.sh

 

Edit script to specify which device is your SD card:

$ vi system.sh

 

Install new kernel onto microSD card:

$ sudo ./tools/install_kernel.sh

 

Installing 3.8.13-bone79-modules.tar.gz to /dev/sdd2

info: [3.8.13-bone79] now installed...

This script has finished...

For verification, always test this media with your end device...

 

Step 6: Boot new kernel

Boot BBB with the updated microSD card:

$ dmesg| head

[ 0.000000] Booting Linux on physical CPU 0x0

[ 0.000000] Initializing cgroup subsys cpu

[ 0.000000] Linux version 3.8.13-bone79 (XXXX@YYYY) (gcc version 4.7.3 20130328 (prerelease) (crosstool-NG linaro-1.13.1-4.7-2013.04-20130415 - Linaro GCC 2013.04) ) #4 SMP Sat Oct 31 13:00:55 CDT 2015

 

$ uname -a

Linux beaglebone 3.8.13-bone79 #4 SMP Sat Oct 31 13:00:55 CDT 2015 armv7l GNU/Linux

 

$ find /lib/modules/3.8.13-bone79/|grep fbtft

/lib/modules/3.8.13-bone79/kernel/drivers/video/fbtft

/lib/modules/3.8.13-bone79/kernel/drivers/video/fbtft/fb_pcd8544.ko

/lib/modules/3.8.13-bone79/kernel/drivers/video/fbtft/fb_ili9486.ko

 

/lib/modules/3.8.13-bone79/kernel/drivers/video/fbtft/fbtft.ko

 

Edit u-boot config file uEnv.txt so the SPIDEV1 loads at boot and HDMI & eMMC are not loaded

cape_disable=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN,BB-BONE-EMMC-2G

cape_enable=capemgr.enable_partno=BB-SPIDEV1

 

For reference, this is my uEnv.txt

 

Verify that HDMI & eMMC are not loaded and SPIDEV1 is loaded:

NOTE: My BBB has no need for HDMI or eMMC. It may not be completely necessary to disable, but I did not investigated this.

$ cat /sys/devices/bone_capemgr.9/slots

0: 54:PF---

1: 55:PF---

2: 56:PF---

3: 57:PF---

4: ff:P-O-- Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G

5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI

6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN

7: ff:P-O-L Override Board Name,00A0,Override Manuf,BB-SPIDEV1

 

Step 7: Load fbtft driver & test display:

Photos of breadboard wiring using SPI1 (CS0, MOSI, SCLK), D/C, RESET.

 

Load fbtft st7735r driver for adafruit18 (Adafruit 1.8" TFT LCD display):

$ sudo modprobe fbtft_device busnum=1 name=adafruit18 debug=7 verbose=3 gpios=dc:48,reset:60

 

Console should now appear on the display. Refer to photos.

 

NOTE: if you have not already done, so run script to make sure all the free space on SD card can be utilized

$ sudo /opt/scripts/tools/grow_partition.sh

 

NOTE: apt-get may fail with warning "There is no public key available for the following key IDs". Fix by running running:

$ sudo apt-get install debian-keyring debian-archive-keyring

$ sudoe apt-get update

 

Display image file on the display with fbi:

$ sudo apt-get install fbi

$ wget https://kernel.org/theme/images/logos/tux.png

$ sudo fbi -d /dev/fb0 -T 1 -a tux.png

using "DejaVu Sans Mono-16", pixelsize=16.67 file=/usr/share/fonts/truetype/ttf-dejavu/DejaVuSansMono.ttf

 

Play video clip on the display with mplayer:

$ sudo apt-get install mplayer

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

$ sudo mplayer -nolirc -vo fbdev:/dev/fb0 scale=WIDTH:128 hst_1.mpg

 

Kernel log with verbose debug output for adafruit18:

 

If using the Adafruit 2.2" TFT LCD display, then specifyadafruit22a [note: the "a" suffix is important]

$ sudo modprobe fbtft_device busnum=1 name=adafruit22a debug=7 verbose=3 gpios=dc:48,reset:60

 

fbi and mplayer all work OK for adafruit22a.  Kernel log with verbose debug output for adafruit22a:

 

Links




Homepage: http://www.element14.com/community/community/designcenter/single-board-computers/next-gen_beaglebone/blog/2015/11/19/beaglebone-black-build-fbtft-drivers-for-latest-linux-3813-kernel
Registrar: pdp7.blogspot.com


Tags: documentation;demo;completebbblack;
Projected created on: Wed Dec 02 2015 01:20:12 GMT-0000 (UTC)
Submitted by: pdp7.blogspot.com
Last updated on: Wed Dec 02 2015 01:21:52 GMT-0000 (UTC)

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