yep, that sounds like it should all workGood. In our project we will be using CM4 and CM5 interchangeably, as the design allows for both.
Additionally, we have an STM32 microcontroller connected to the CM via SPI and UART. The device will be fully operated remotely with very limited physical access. Our goal is to be able to turn the CM4/5 ON and OFF remotely.
We also want to handle the special case of issuing the sudo shutdown now command as mentioned.
Based on your guidance, here is the concept we are considering:
- The STM32 periodically polls the CM4/CM5 with a simple "heartbeat" over UART.
- If the CM4/CM5 does not respond and a timeout expires, this indicates that the RPi is in the halt/shutdown state. The STM32 will then pull the GLOBAL_EN (CM4) or PMIC_Enable (CM5) line to GND.
- This will reset the PMIC/CM and reload the system into RAM.
Do I understand this correctly?
Statistics: Posted by cleverca22 — Thu Jul 31, 2025 5:32 pm