Pocket Beagle software documentation

General Discussion
1

I am in the process of porting a board and code from the older Pocket Beagle to the new Pocket Beagle 2 and am looking for software development documentation. The board and code are on github here: GitHub - RobertPHeller/CommandStationsAndBoosters: Command Stations and Boosters · GitHub, specificly under PocketBeagleCommandStation_SMD (board) and BBBCommandStationOpenMRN-RevC-PB2 (software). The code will use the PRUs (both of them) for low-level bit-banging (DCC signals being sent to HBridge chips) and doing high-level management and control with the main ARM64 cores. There seems to be a lack of software development documentation. Is that documentation in the works? If so, when will it be available? And where?

2

If you have high-level guidance, even something like emphasizing the need for an article on porting existing PRU code from PocketBeagle to PocketBeagle 2, that could help drive the activity and I could give you a better guideline.

3

What I need help with right now is mapping from “GPIOi_j” to base level GPIO #’s – eg what to send to /sys/class/gpio/export. And what are the proper values to give to the config-pin command.

4

I’ll also need to know the correct /dev names for user mode SPI and I2C drivers. I think the PRU code itself does not need changing, depending on if the interprocess subsystem has changed.

5

Those days are over on mainline. Load an overlay with what gpio you want and use gpio-led for output control, gpio-key for input..

Here’s an example with ‘every’ gpio blinking… BeagleBoard-DeviceTrees/src/arm64/overlays/k3-am62-pocketbeagle2-led-all.dtso at v6.18.x · beagleboard/BeagleBoard-DeviceTrees · GitHub

if the gpio’s are controlled from the pru, just set the pru gpio configuration in the overlay.

Regards,

6

List of i2c/spi aliases (/dev/i2c0 = main_i2c0 for example)..

7

Is there documentation? The example is not documented in any meaningful way. I have a C++ program that needs to access selected pins under program control. How does the C++ code access GPIO pins. I understand about overlays setting pin control, but once set how does a user-mode C++ program actually access the pins? What does the API look like? The C++ program needs to set or clear certain pins. Other pins need to be “read”. In Arduino terms, I need functions like digital_read() and digital_write() (but obviously, not actually the Arduino library). I have an existing library here: openmrn/src/os/LinuxGpio.hxx at master · bakerstu/openmrn · GitHub that the existing version uses. I need a compatible API. Each pru needs to bit-bang one bit (just one output bit each).

Also, I need to know how the current incarnation of the interprocess communication system works. The main (Linux) system needs to send a [DCC] packet to the PRUs, that the PRUs will bit-bang out to the HBridge drivers (the pulses need to be properly timed to create the proper DCC square waves.

Random examples are not really helpful, I need real documentation. Does this documentation exist anywhere?

8

Output High:

voodoo@am6232-pb2-85:~$ echo 1 > /sys/class/leds/beaglebone\:green\:usr1/brightness

Output Low:

voodoo@am6232-pb2-85:~$ echo 0 > /sys/class/leds/beaglebone\:green\:usr1/brightness

Or you can use libgpiod, to access the gpio directly in your c/etc..

Regards,