Push button
There is a recessed push button that is easily accessible removing the front panel. When
this button is pressed, the Strato Pi CM controller will set GPIO38 high, so that an
application can easily detect it by simply polling this GPIO line.
LED
Strato Pi CM has an on-board LED that can be controlled using GPIO16. Simply set
GPIO16 high to turn on the LED.
The Strato Pi utility offers commands to control the LED.
LED on continuously:
$
sudo strato led on
LED off:
$
sudo strato led off
LED on for 500 milliseconds:
$
sudo strato led 500
LED on for 500 milliseconds, followed by 100 milliseconds off, repeated three times:
$
sudo strato led 500 100 3
Hardware watchdog
Strato Pi CM implements a dedicated hardware watchdog circuit that can be used to
perform the hardware reset of the Raspberry Pi Compute Module.
Being controlled by Raspberry Pi’s GPIO pins, it is extremely easy to control watchdog
operation using simple custom scripts in your application.
Watchdog default behavior is described below, but all timing parameters and control logic
can be modified as described in the "Strato Pi Logic Controller Advanced Configuration
Guide" document.
The watchdog is normally disabled. To enable it, set GPIO39 pin to high. While GPIO39 is
high, the Strato Pi CM controller will watch for state changes of the GPIO32 heartbeat pin.
You should ensure that GPIO32 flips its state between high and low faster than every 60
seconds.
If the Strato Pi CM controller doesn’t see GPIO32 changing state for more than 60
seconds, it will initiate a shutdown procedure, rising the GPIO17 timeout pin to high, to
signal that a watchdog timeout has occurred.
If possible, you should immediately initiate a software shutdown on Raspberry Pi Compute
Module, and set the GPIO18 shutdown pin to high. When GPIO18 is set to high or 60
seconds after the timeout, Strato Pi CM will wait 60 seconds more, then reset the
Raspberry Pi Compute Module (pulling the RUN line low).
22
Strato Pi CM User Guide
