COM AM335x Linux: Difference between revisions
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Revision as of 14:36, 22 March 2016
Linux virtual machine for development
- Please have a look at: Virtual Machine for Application Development
Linux Kernel
Sources for the DHCOM AM335x Linux Kernel v4.1.x
- The latest Linux Kernel source code is available on GitHub: https://github.com/dh-electronics/linux-am33x
How to build a Kernel
Get sources from Github
Configure and build the kernel using 5 threads in a separate build directory
|
Update the Kernel and Devicetree with U-Boot
Please refere to the DHCOM Update Mechanism for am335x.
Update Kernel and Devicetree on a running Linux
Kernel
Devicetree
Reboot System
|
Debian Rootfilesystem
Available Rootfilesystems
Please have a look at the DHCOM AM335x Downloads section.
External Documentation
- The Debian Administrator's Handbook: A reference book presenting the Debian distribution, from initial installation to configuration of services. The administration and configuration chapters apply to our Debian based root filesystems.
- Debian Documentation
Login
Debian GNU/Linux 8 dhcom ttyO0 dhcom login: root |
Shutdown
# shutdown -h now |
Calibrating the touchscreen (tslib has to be installed)
# source setup_tslib.sh # setup environment for use of tslib |
- Check the enviroment variable "TSLIB_TSDEVICE=/dev/input/event0" with printenv if an error occurs.
How to create a microSD-card with a rootfilesystem on it
1. Format a microSD card like following (in linux e.g. gparted, palimpsest) with Master Boot Record partition scheme
P1 ext3, name="boot" (Primary partition: 100MiB) |
2. Untar the root file system to the "rootfs" partition of the microSD card (Don't copy the tar archive directly to the microSD card)
Start the Console on Linux |
Remark: If you got a *.tar.gz file so type tar xfzv ... to extract the rootfilesystem.
Kernel Userspace Interfaces to Access Hardware
Serial (UART) Interfaces
DHCOM UART 1 (Rx Tx Rts Cts) /dev/ttyO0
DHCOM UART 2 (Rx Tx) /dev/ttyO1
DHCOM UART 3 not available
I2C Interfaces
DHCOM I2C 1 /dev/i2c-2
DHCOM I2C 2 not available On Module Devices /dev/i2c-0
SPI Interfaces
DHCOM SPI 1 /dev/spidev1.1
DHCOM SPI 2 not available
- Remark: DHCOM SPI1 interface doesn‘t work with DHCOM Premium Developer Kit (HD00013).
- Reason: At DHCOM Premium Developer Kit SPI 1 isn‘t connected, because otherwise AM335x doesn‘t boot with the current schematic.
MMC/SD/eMMC Interfaces
DHCOM SD-Interface /dev/mmcblk0pX
(optional)on module µSD Card /dev/mmcblk0pX
(optional)on module eMMC /dev/mmcblk1pX
- 'X' has to be replaced with the partition number
- DHCOM SD-Interface or on module µSD slot is available
Control the display brightness
echo [0..8] > /sys/class/backlight/backlight/brightness
Control GPIOs
DHCOM Name: alt. DHCOM Name: SO-DIMM Pin# Linux <GPIO#> GPIO A 154 20 GPIO B 156 115 GPIO C 162 116 GPIO D 163 65 GPIO E 164 114 GPIO F 165 112 GPIO G 167 111 GPIO H 173 7 GPIO I 175 113 CIF HSYNC GPIO J 74 117 CIF PCLK GPIO K 72 57 CIF MCLK GPIO L 70 56 CIF VSYNC GPIO M 68 55 CIF D9 GPIO N 66 54 CIF D8 GPIO O 64 51 CIF D7 GPIO P 62 50 CIF D6 GPIO Q 60 49
- Remark: The parallel camera interface is not available on DHCOM AM335x.
- Export
echo <GPIO#> >/sys/class/gpio/export
- Remark: Have a look into
/sys/class/gpio/
for already configured gpios.
- Remark: Have a look into
- Set direction
echo in >/sys/class/gpio/gpio<GPIO#>/direction
echo out >/sys/class/gpio/gpio<GPIO#>/direction
- Set state
echo 0 >/sys/class/gpio/gpio<GPIO#>/value
echo 1 >/sys/class/gpio/gpio<GPIO#>/value
Initialize and Test CAN Interface
- Initialize:
ip link set can0 up type can bitrate 500000
- Send test message via cansend (part of can-utils):
cansend can0 100#11.2233.44556677.88
- Receive can messages (part of can-utils):
candump can0
- Get can-utils:
Configure your own display
- To configure your own display you have to do the following steps:
- 1. Type in the display values into the device tree file
/arch/arm/boot/dts/imx6qdl-dheva01.dtsi
- Where in the file?
Parallel display: display@di0
LVDS display: &ldb
Remarks: If you don't want to use both interfaces comment the unwanted out! The frame buffer resolution depends on the higher display resolution of both displays
- How?
- Here is an example:
display-timings { DataImage_7inch_FG0700G3DSSW { clock-frequency = <33260000>; hactive = <800>; vactive = <480>; hback-porch = <86>; hfront-porch = <42>; vback-porch = <33>; vfront-porch = <10>; hsync-len = <128>; vsync-len = <2>; hsync-active = <0>; vsync-active = <0>; de-active = <1>; pixelclk-active = <1>; }; };
- 2. Build the device tree dtb files
ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make dtbs
- 3. Copy the dtb files onto your boot partition
/dtbs
(SD, µSD or eMMC) - The built
imx6xx-dheva01.dtb
device tree files will you find inarch/arm/boot/dts