Designed by UUGear, the Witty Pi 5 HAT+ is a power scheduler board for Raspberry Pi that features an RP2350 MCU for running scheduling logic. It includes a high-precision RTC with voltage and temperature monitoring for automated power on/off, making it suitable for solar-powered projects, environmental monitors, and industrial controllers that require scheduled power on/off control to extend battery life.
The board follows the Raspberry Pi HAT+ specification and accepts power from either a 6V–30V DC input through a terminal block or a 5V USB-C supply, while delivering up to 5A to the Raspberry Pi and connected peripherals. It can also work as a simple UPS, thanks to its dual “ideal diode” configuration with an automatic switchover feature in case of power failure. Other hardware features include an onboard DC/DC converter, an ID EEPROM for HAT+ identification, a CR2032 RTC battery, and a wide –30°C to +80°C operating temperature range.
Witty Pi 5 HAT+ specifications:
- Compatibility – Raspberry Pi SBCs with 40-pin header, including A+, B+, 2B, Zero, Zero W, Zero 2 W, 3A+, 3B, 3B+, 4B, 5B
- Microcontroller – Raspberry Pi RP2350A MCU
- CPU
- 2x Arm Cortex-M33 cores @ 150 MHz
- 2x Hazard3 RISC-V cores @ 150 MHz
- Up to two cores can be used at any time (configured at boot)
- Memory – 520KB SRAM
- Storage – 8KB OTP
- Package – QFN-60; 7×7 mm
- CPU
- Storage – 16MB flash memory
- USB – USB Type-C port for power, programming, and debugging
- Sensor – TMP112 temperature sensor with 0.0625°C resolution
- Expansion
- 40-pin GPIO header (I²C only, no other GPIO used by the HAT+)
- 7-pin extension header (Unpopulated)
- Internal I2C pads (Unpopulated)
- Debugging
- SWD header for RP2350 (Unpopulated)
- Serial port connector (Unpopulated)
- Misc
- RX8025T-UB RTC with ±3.8 to 5 ppm accuracy, onboard CR2032 battery holder with external battery input via solder pads
- ON/OFF push button
- Status LED
- RP2350 reset header (Unpopulated)
- BOOTSEL button
- HAT+ compliant ID EEPROM on dedicated I²C bus
- Power
- Dual power inputs with automatic failover:
- 5V via USB Type-C (VUSB)
- 6V–30V via KF350-2P screw terminal (VIN)
- Onboard DC/DC converter (TPS54540)
- Solder pads for VUSB
- Solder pads for VOUT
- Up to 5A output current for Raspberry Pi and peripherals
- 0.8 mA standby current, can be reduced to ~0.8 mA (firmware dependent)
- Dual power inputs with automatic failover:
- Dimensions – 65 × 56 × 19 mm (Raspberry Pi HAT+ form factor)
- Weight – 28 grams (net, without accessories)
- Temperature Range – -30°C to +80°C
- Humidity – 0–80% RH, non-condensing, non-corrosive
Previous Witty Pi boards depend on software running on the Raspberry Pi for scheduling, which can fail if the OS crashes or does not boot. With the latest Witty Pi 5, all scheduling logic runs on the onboard RP2350 MCU, and configuration is handled via the open-source (wp5) command-line tool and a background daemon (wp5d), both open-source and released under the BSD-3-Clause license. All communication is over I²C (default address 0x51, configurable), in full compliance with the Raspberry Pi HAT+ specification, while leaving GPIOs free for other peripherals.
Scheduling scripts are stored in the board’s 16MB flash and run independently of the Raspberry Pi, which ensures power cycling even if the OS fails. The firmware supports traditional .wpi loop scripts, the newer linear .act format for precise actions. Firmware updates are straightforward, and you just need to hold the BOOTSEL button to enable the USB mass storage drive and drag-and-drop the .uf2 updates, while a virtual serial interface provides real-time debug output. More information can be found in its user manual.
We have written about high-power UPS HATs like the Waveshare UPS HAT (E), the SupTronics Raspberry Pi 5 UPS HAT, and the AQEX qUPS-P-BC-2.0 UPS HAT, which are backup power solutions but are not “power scheduler” HATs for the Raspberry Pi like this one. The closest competitor we have covered is the PiSugar 3, which features an onboard Real-Time Clock (RTC) for scheduled booting, soft shutdown capabilities, and custom programmable buttons.
The Witty Pi 5 HAT+ is available now on the UUGear store for €39.00 (approx. $42 USD ex. VAT) and on Adafruit for $59.95 (price likely including US tariffs). The package includes the board, copper standoffs, and mounting screws.
Debashis Das is a technical content writer and embedded engineer with over five years of experience in the industry. With expertise in Embedded C, PCB Design, and SEO optimization, he effectively blends difficult technical topics with clear communication
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