Communicate with the Safety Processor from the RPU

This section describes how to communicate with the Safety Processor from the RPU.

Sample applications

The sample applications are available in the scobc-sp-sample repository.

Setup

Set up the workspace and download the sample application:

$ west init -m https://github.com/spacecubics/scobc-sp-sample.git scobc-sp-sample-workspace
$ cd scobc-sp-sample-workspace
$ west update

Shell sample

Build and flash the shell sample application to the RPU. The application will communicate with the Safety Processor from the shell commands using the IPC (Inter-Processor Communication) interface.

$ west build -p always -b scobc_v1/versal_rpu scobc-sp-sample/shell
$ west flash --pdi /path/to/pdi

Then, connect to the RPU shell using a serial terminal program. The RPU shell is available on a serial port such as /dev/ttyUSB2, depending on your system:

$ tio /dev/ttyUSB2
*** Booting Zephyr OS build v2026.06 ***
SC-OBC Safety Processor IPC shell sample

uart:~$

Get sensor values

The sensor command reads the Safety Processor sensor values. The command has two subcommands: temp and current. The temp subcommand reads the temperature sensors on the board, while the current subcommand reads the current values from the C/V (Current/Voltage) monitors.

uart:~$ sensor -h
sensor - Read Safety Processor sensor values
Subcommands:
  temp     : Read temperature sensors
  current  : Read current monitors
uart:~$ sensor
Temp Average: 40.500 degC
CV Total: 0.907 A
CV SYS: 0.158 A
CV PS: 0.545 A
CV PL: 0.204 A
uart:~$ sensor temp
Temp Average: 40.500 degC
uart:~$ sensor current
CV Total: 0.907 A
CV SYS: 0.158 A
CV PS: 0.545 A
CV PL: 0.204 A

Get and set boot memory port

The bootmem command gets or sets the boot memory port. The command takes an optional argument of 0 or 1. If no argument is provided, the command returns the current boot memory port. If an argument is provided, the command sets the boot memory port to the specified value.

uart:~$ bootmem -h
bootmem - Get/Set boot memory: 0 or 1
uart:~$ bootmem
Boot memory port: 0
uart:~$ bootmem 1
Boot memory port: 1

While the power remains on, the bootmem value is retained, but it returns to 0 on the next cold boot. This is because the Safety Processor does not yet implement a configuration persistence feature.