Building a kernel for imx233-Olinuxino-Micro + wireless + TFT LCD [ST7735R/ILI9325] – I

We had our imx233-Olinuxino-Micro in its box for too long but we finally managed to run some electrons through it 🙂

We needed to have our wifi USB module – Realtek RTl8192cu Chipset working. Also, we wanted to connect our TFT LCD displays : the 1.8″ Color TFT LCD display with MicroSD Card Breakout – ST7735R, and try also the 2.8″ 18-bit color TFT LCD with touchscreen breakout board – ILI9325. [Check the next posts for wiring instructions.}

After some pains in finding the right linux kernel and drivers…we followed the great tutorial provided by g-lab, and made a few changes. Hopefully this will be of help for some of you out there. So here we go…

Getting some files

1. Start with a working SD card image. We got imx233 Debian 2GB SD-card image based on Kernel 3.11 following the olimex.com link.

Want to know how to make a bootable SD Card? Look here…

2. Get the package provided by g-lab link, which contains Freescale imx-bootlets, utility elftosb2 and patches for the imx23-board.

git clone -b 3.13-rc4  https://github.com/koliqi/imx23-olinuxino

Building the kernel

You will need to know how to build your own kernel and create a bootable image.

We used the 3.18.3 kernel. You can try another one. It is likely that any 3.x.x will work too.

cd imx23-olinuxino/kernel
wget https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.18.3.tar.xz

To enable SPI we made our own patch. Get it as follows or Read on what you need to do...

pico arch/arm/boot/dts/imx23-olinuxino.dts

ssp1: ssp@80034000 {
                #address-cells = <1>;
                #size-cells = <0>;
                compatible = "fsl,imx23-spi";
                pinctrl-names = "default";
                pinctrl-0 = <&spi2_pins_a>;
                status = "okay";  
};

ssp1: ssp@80034000 {
                #address-cells = <1>;
                #size-cells = <0>;
                compatible = "fsl,imx23-spi";
                pinctrl-names = "default";
                pinctrl-0 = <&spi2_pins_a>;
                status = "okay";
        
              spidev: spidev@0 {
              compatible = "spidev";
              spi-max-frequency = <1000000>;
              reg = <1>;
              };    
};

wget http://www.opentronix.com/pub/olimex012015/spi_dts.patch

tar xvf linux-3.18.3.tar.xz
ln -s linux-3.18.3 linux-mainline

cd into directory linux-mainline to apply  i2c patches for imx23-olinuxino board. These are required for your i2c communication devices. Also, apply our SPI patch.

cd linux-mainline
patch -p1 <../0001-ARM-imx23-olinuxino-Add-i2c-support.patch
patch -p1 < ../spi_dts.patch

We found this great driver for our LCD’s. Download sources and install it:

cd drivers/video/fbdev
git clone https://github.com/notro/fbtft.git

echo 'source "drivers/video/fbdev/fbtft/Kconfig"' >> Kconfig 
echo 'obj-y += fbtft/' >> Makefile
cd ../../../

wget http://opentronix.com/pub/olimex012015/.config

If you do not use the .config we provide here, you will have to add a few things with the menuconfig. Read more.

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- menuconfig

[*] Use appended device tree blob to zImage (EXPERIMENTAL)
[*] Supplement the appended DTB with traditional ATAG information
(console=ttyAMA0,115200 root=/dev/mmcblk0p2 rw rootwait) Default kernel command string

<*> Support for small TFT LCD display modules --->
   [And inside select yours. As an example, in our case:]
    <M> FB driver for the ILI9325 LCD Controller
    <M> FB driver for the ST7735R LCD Controller
    <M> Generic FB driver for the TFT LCD displays
    <M> Module to for adding FBTFT devices

Compile kernel

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- zImage modules

Mount your SD card and do [NOTE: Check where is your SD card partition is mounted and enter the path in the following line. For example we use kubuntu and had it mounted in /media/opiliao/rootfs]:

sudo make INSTALL_MOD_PATH=<add your SD card partition path here> ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- modules_install

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- imx23-olinuxino.dtb

cat arch/arm/boot/zImage arch/arm/boot/dts/imx23-olinuxino.dtb > arch/arm/boot/zImage_dtb

Bootlets

Switch into directory boot/elftosb-0.3 and make symbolic link into the compilers default PATH [elftosb2 should be located at /usr/sbin/elftosb2]

cd ../../boot/elftosb-0.3
sudo ln -s pwd/elftosb2 /usr/sbin/

Next, switch into directory boot and do:

cd ..
tar xvzf imx-bootlets-src-10.05.02.tar.gz

Now, switch into directory boot/imx-bootlets-src-10.05.02 and apply patches

cd imx-bootlets-src-10.05.02
patch -p1 <../imx23_olinuxino_bootlets.patch

This patched package require zImage in this directory. We have created zImage_dtb instead.

ln -s ../../kernel/linux-mainline/arch/arm/boot/zImage_dtb  ./zImage

make CROSS_COMPILE=arm-linux-gnueabi- clean
make CROSS_COMPILE=arm-linux-gnueabi-

You should be ready to dump the image to your SD card. If your SD device is /dev/sdb1 do: [Note: you can check it by doing: sudo fdisk -l]

sudo dd if=sd_mmc_bootstream.raw of=/dev/sdb1

The card is ready, insert on your board and boot….IT WORKS!

Take a 10 min break before continuing…see you in the next post 😉