Witty Pi 3 Mini: Realtime Clock and Power Management for Raspberry Pi

by UUGear

Witty Pi 3 Mini adds RTC (DS3231SN) and power management to your Raspberry Pi, and can define complex ON/OFF sequence with simple script.

After installing Witty Pi 3 Mini on your Raspberry Pi, you get some amazing new features:

  • You can gracefully turn on/off Raspberry Pi with single tap on the switch.
  • After shutdown, Raspberry Pi and all its USB peripherals’ power are fully cut.
  • Raspberry Pi knows the correct time, even without accessing the Internet.
  • Raspberry Pi knows the temperature thanks to the sensor in RTC chip.
  • You can schedule the startup/shutdown of your Raspberry Pi.
  • You can even write a script to define complex ON/OFF sequence.
  • Monitor external voltage and turn on/off your Raspberry Pi accordingly.

Witty Pi 3 Mini supports all Raspberry Pi models that has the 40-pin GPIO header, including A+, B+, 2B, Zero, Zero W, 3B, 3B+, 3A+ and 4B.

Witty Pi 3 Mini uses the same software with Witty Pi 3. You just need to run these two commands in your Raspberry Pi to install the software:

pi@raspberrypi:~ $ wget http://www.uugear.com/repo/WittyPi3/install.sh

pi@raspberrypi:~ $ sudo sh install.sh

Comparing to Witty Pi 3, Witty Pi 3 Mini uses the same RTC chip (DS3231SN) and same micro-controller (ATtiny841). The main difference is the LDO voltage regulator (LM29150) is not populated on Witty Pi 3 Mini. This reduces the cost for those who don’t need this LDO, and also make things easier to integrate a different DC/DC module into Witty Pi 3 Mini.

Unlike Witty Pi 3 which uses a 3V button battery for off-power time keeping, Witty Pi 3 Mini uses a super capacitor (0.08F, or 80000uF) for this purpose.

You can find more information in its user manual: http://www.uugear.com/doc/WittyPi3Mini_UserManual.pdf


Each Witty Pi 3 Mini package contains:

  • Witty Pi 3 Mini board x 1
  • M2.5 x 10mm plastic screw x 4
  • 4mm spacer x 4
  • M2.5 plastic nut x 4


Dimension: 65mm x 30mm x 4mm
Weight 8g (net weight)
Micro Controller ATtiny841 (datasheet)
Realtime Clock DS3231SN (datasheet)
LED Indicator Red LED: lights up when Raspberry Pi gets powered.
White LED: lights up for a few seconds when a shutdown command is received, or blinks when device is standing by.
Connector 20×2 surface-mounted header with 2.54 mm pitch and 2mm plastic height.
Micro USB female connector as 5V DC input.
Unpopulated 7-pin header for extension or integration.
Unpopulated 3-pin header/connector for VIN, GND and 5V.
Time Keeping Using 0.08F super capacitor as time keeping power source. Allows about 17 hours off-power time keeping.
Power In DC 5V (via micro USB). Possible to connect external DC/DC converter (not included) and also have VIN monitored.
Output Current Up to 2.5A for Raspberry Pi and its peripherals. If using external DC/DC converter, the output current is also limited by the capability of DC/DC converter.
Standby Current ~ 1mA
Operating Temperature -30℃~80℃ (-22F~176F)
Storage Temperature -40℃~85℃ (-40F~185F)
Humidity 0~80%RH, no condensing


Witty Pi 3 Mini uses the same firmware and software with Witty Pi 3.

The source code of firmware and software can be found on Github: https://github.com/uugear/Witty-Pi-3


You can now use this web app to create and debug the schedule script for Witty Pi.