On/Off power button with "soft off" functionality


Hi Everybody,

I’m designing a product that will be battery powered and (hopefully) built using the Fin.
I’m wondering if anybody has implemented an on/off button that gracefully shuts down the board when pushed for off. It’d also be great to have the “hold for x seconds to force shut off” functionality.

Could the co-processor be used for this purpose?
Since my product will be battery powered, drain while off is a concern. Do we know how much power the system consumes when the pi module is shut off?



Hello Caleb,

The best approach for what you’re mentioning would be to use the coprocessor, since it has the capability of managing the Compute Module power rail. You can implement a button that directs the coprocessor to power the Compute Module on and off (force shut down) or communicate with the Compute Module to allow for a graceful power off.

The power consumption will depend on how heavy is the application running on the coprocessor. For example, if the CM is turned off and the coprocessor is running a very simple BLE application, the power consumption is around 20mW (we measured this using a 12V PSU).