Pololu Balboa 32U4, User Manual, Page: 22 / 97

The power switch circuit also offers several alternate pushbutton connection options that result in
push-on-only or push-off-only operation, and additional inputs enable further power control options like
allowing your robot to turn off its own power. These advanced control options are available through the
button connection pins and four control inputs:
PIN Description
PWRA
Connect through momentary switch to pin “PWRB” for standard push-on/push-off
operation. Connect through momentary switch to ground for on-only operation.
PWRB
Connect through momentary switch to pin “PWRA” for standard push-on/push-off
operation.
ON
A high pulse (> 1 V) on this pin turns on the switch circuit. This pin only functions when
pushbutton operation is enabled (i.e. the button jumper has not been cut).
OFF
A high pulse (> 1 V) on this pin turns off the switch circuit (e.g. allowing a powered
device to shut off its own power).
This pin only functions when pushbutton operation
is enabled.
CTRL
With pushbutton operation enabled, this pin directly determines the state of the switch
circuit. A high pulse (> 1 V) on this pin turns on the switch; a low pulse (e.g. driving
the pin low with a microcontroller output line or pushing a button connected from this
pin to ground) turns the switch off. Leave this pin disconnected or floating when not
trying to set the switch state. Note that this pin should not be driven high at the same
time the “OFF” pin is driven high.
GATE
With pushbutton operation disabled (button jumper cut), this pin controls the state of
the switch circuit: driving it low turns the switch on, while letting it float turns the switch
off. Connect through slide or toggle switch to ground for on/off operation. Leave this
pin disconnected or floating for proper pushbutton operation. We recommend only
ever driving this pin low or leaving it floating; this pin should
never be driven high while
the slide switch is in the “On” position.
5 V and 3.3 V regulators
VSW supplies power to a 5 V regulator, whose output is designated VREG . The battery voltage is
regulated to 5 V by an MP4423H switching buck converter; although the regulator itself works with
input voltages up to 36 V, the motor drivers limit the control board’s maximum input voltage to 10.8 V.
When available, VREG is generally used to supply logic power for the ATmega32U4, motor drivers,
and encoders. The rest of the regulator’s achievable output current, which depends on input voltage
and ambient conditions, can be used to power other devices; this can include an attached Raspberry
Pi (which typically draws a few hundred milliamps). Under typical conditions, up to 2 A of current is
available from the VREG output. (We also make a
standalone regulator
[https://www.pololu.com/product/
Pololu Balboa 32U4 Balancing Robot User’s Guide © 2001–2019 Pololu Corporation
3. Balboa 32U4 in detail Page 22 of 97