BeagleboneLab

Embedded Linux and device driver programming using beaglebone black
This repo contains 3 resources for the am335xx soc based beaglebone board

1. Compiled boot binaries
2. uEnv.txt for various u-boot configurations
3. Device setups and drivers. Build and test instruction sections below apply to this resource
4. Misc scripts

Compiled boot binaries

Bootloader binaries (MLO, SPL and u-boot.img) required to boot Beaglebone black with Embedded Linux
This directory also contains the default device tree binary for BBB
uImage is the actual kernel image, custom built with the linux kernel source and required static modules
All these files should be present in the BOOT partition of the SD card while booting

uEnv.txt

uEnv.txt is used to set environent paramters during initial booting process (u-boot) of the board
This file along with u-boot load the kernel, dtb and initramfs (if applicable otherwise points to the device partion holding the root filesystem) into memory
As per the suffix, different environment vars are used for different boot configurations
While adding any of the uEnv files in the BOOT partition ensure removing the suffix from the filenames. It should be named uEnv.txt only

Misc scripts

usbnet.sh script is used to enable internet connection on BBB
This script accepts 2 arguments:

1. out-interface which is the interface of the host with internet connection
2. in-interface which is the input ethernet interface of the board

Example exec of the script will be:

./usbnet.sh wlp4s0 eth0

Devices and drivers

Different types of device and driver setups for managing platform devices
Pseudo character device drivers can be tested on any host running Linux
Cross compilation of drivers for ARM based processors has been taken care of in the Makefile (follow build and test instructions below)

Build Instrctions

Enter the directory of driver to be tested under Drivers/ directory
Run the following command to build a kernel object for ARM

make

Run the following command to build a kernel object for x86_64 based machine

make host

Test instructions

All the drivers were tested on an ARM based AM335xx SOC (Beaglebone black SBC)
Alternatively some drivers like the pseudo character driver can be tested directly on host with appropriate build command
The kernel module g_ether must be present to transfer files using ethernet over usb otherwise connect a separate ethernet cable to the board for file transfer
Run the following command in the BBB terminal to setup a network interface over usb

sudo ifconfig usb0 192.168.7.2 netmask 255.255.255.0

Try pinging 192.168.7.1 which should be host the SBC is connected to test if the interface works
Copy all the kernel objects including drivers and devices with the following command

make copy-driver

Device tree binaries can be transferred with the following command

make copy-dtb

Load the device or driver with the following command

sudo insmod drviers/<driver/device-name>.ko

Remove or unload the device or driver with the following command

sudo rmmod drviers/<driver/device-name>.ko

The above instructions for loading and unloading are under the assumption that your current directory is /home/debian/