oresat-linux-prucam

Kernel module, device tree overlay, and PRU firmware to interface to camera using the PRUs on the AM335x.

NOTE: This was tested on Debian with kernel 5.10. TI's PRU support libraries are constantly changing, so this likely does not work on older kernels anymore.

What is a PRU?

Programible Real-time Units. It a microcontroller that shares pins and other resource with the core processor allowing for custom interface to other hardware like cameras. See TI PRU-ICSS webpage for more details.

Supported cameras

• AR0130CS
• AR0134CS

Build and install prucam

NOTE: The kernel module requires both the device tree overlay and pru firmware binaries to be installed to work, so build and insert it last.

Device tree overlay

• Install dependencies: $ sudo apt install device-tree-compiler
• Compile dtbo: $ make -C src/device_tree_overlay
• Install dtbo: $ sudo make -C src/device_tree_overlay install
• Edit /boot/uEnv.txt
  • Change the #dtb_overlay=<file8>.dtbo line to dtb_overlay=/lib/firmware/prudev-00A0.dtbo
  • Make sure the #enable_uboot_cap_universal= line is commented out.
• Reboot system to apply device tree overlay: $ sudo reboot

PRU firmware

• Install dependencies: $ sudo apt install ti-pru-cgt-v2.3 ti-pru-software-v6.0
• Compile binaries for both PRUs: $ make
• Install binaries for both PRUs: $ sudo make install

Kernel module

• Install the kernel headers: $ sudo apt-get install linux-headers-`uname -r`
• Build kernel module: $ make -C src/kernel_module clean all
• Insert kernel module: $ sudo insmod src/kernel_module/prucam.ko
• Note: To remove kernel module: $ sudo rmmod prucam

Test prucam

• $ cd testing/camera-test-c
• Compile: $ make
• Capture image:$ sudo ./test_camera
  • This will produce capture_001.bmp

Debian package

prucam-dkms is the kernel module that provides the sysfs interfaces to the pru and ar013x camera settings. This package will also install the compiled pru firmware and the prucam dtbo. NOTE when install, it will auto load the module.

To build prucam-dkms:

• Install build dependencies: $ sudo apt install --no-install-recommends --no-install-suggestions debhelper fakeroot dkms linux-headers-`uname -r` device-tree-compiler ti-pru-cgt-v2.3 ti-pru-software-v6.0
  • The --no-install-* flags are due to dkms installing linux-headers package for the wrong kernel version
• Build prucam Debian packages: $ ./makedeb.sh