The plan for the LED is to indicate when the Expander is ON with solid green. A yellow blink will be used to indicate low battery. The LED go solid red while the internal 4A breaker is tripped. Once the breaker automatically resets (after the excessive load is removed), the LED will blink red until shutdown. The red blink is done so that after a match you can tell if you ever tripped the breaker. This would be an indication to re-distribute your motors between the microcontroller and the Expander.
The Expander turns on automatically when it senses any PWM signals, thus eliminating another power switch. The unit shuts OFF the motors when PWMs are not present, then the processor goes to sleep. This is done to ensure near zero power draw from the connected battery.
The Dig/Int port (now renamed “Status”) can optionally be connected back to the microcontroller’s digital IO. This will provide status information about the Expander such as battery voltage, circuit breaker status, and breaker trip history.