What is it?

This Arduino shield controls the power supply to an attached Arduino. It uses far less power than an Arduino, so if you don't need the Arduino on all the time your thingy can run for years on a small battery.

View manual

Why did you make it?

I needed something like this for other projects (which are currently happily using it :)

What makes it special?

It has many related desirable features:

• It can use whichever Arduino pins you have available, and doesn't need any sketch at all. Basic use requires only one pin. You pull that pin high to request that the shield turn you off, and it turns you on again when the specified amount of time passes.

• The power-down time can be set with hardware jumpers on the supervisor (from about 1 s to 9 hours).

• Optional low battery sensing: when the battery voltage goes below a certain threshold, the Arduino will be turned on and (after by default about 100 ms power ramp time) an (optional) input line from the supervisor to the Arduino will be brought high. The threshold voltage can be set by replacing a through-hole resistor on the supervisor. The Arduino is woken only when the battery voltage first goes low, but the low battery signal will be asserted whenever the Arduino is fully turned on (i.e. powered up plus 100 ms power ramp time) and the battery voltage is low.

• Optionally, signals from the Arduino to the supervisor can be used to request at run-time that the next sleep be longer sleep than what is specified on the jumpers. This allows the Arduino to wake less often during periods of low activity.

• Screw terminals are provided to power an optional external load when the supervisor requests it using a signal line.

• Two optional user wake-up request lines. The user can connect additional circuitry to the supervisor board to wake the Arduino under other user-defined conditions. The supervisor in turn drives two optional inputs to the Arduino which relay these signals when the Arduino is powered up. The Arduino is woken only when one of these user signals first goes high, but the corresponding signal from the supervisor to the Arduino will be active (high) whenever the Arduino is fully turned on (but see notes about power ramp time below) and the user signal remains high.

• On-off switch for the supervisor (and Arduino and optional load).

• Center-positive barrel jack and screw terminal jacks for connection to battery. The barrel jack safely disconnects the screw terminal supply.

• A simple hardware hack to the Arduino can be used to power its microcontroller from the supervisor's supply, which makes it possible to keep it powered up all the time.

• The current limit, current sense output, and fault detection features of the TPS2H160B high-side switch on the supervisor can be reprogrammed and accessed.