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WSAL23452 – Power Management HAT (B)/en

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Documentation notice: This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

Summary

The Power Management HAT (B) is a power-management add-on for Raspberry Pi. It provides timed power on/off, voltage and current monitoring, an embedded RTC chip, and multiple protection circuits.

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Technical overview

  • Board size: 56.5 mm × 65 mm; mounting hole diameter 3.0 mm.
  • Main processor: RP2040; communication via UART + GPIO; default baud rate 115200 bps (configurable).
  • Input power: USB at 5 V or PH2.0 connector at 3.3–4.2 V (typically a 3.7 V Li battery, not included).
  • Built-in protections: battery reverse-polarity guard, counter-current guard, and real-time voltage/current monitoring.
  • GPIO connections: UART0_TX/RX to RPI D15/D14; I2C1 SDA/SCL to II2 SDA/SCL; user key on GPIO19; soft-shutdown pin to RPI D20; run-state pin to RPI D21; power-control pin (low = off); status LED; input-voltage divider (about 1/10 of input voltage).
  • Demo modes: Button_Ctr (toggle power with the PWR button), Period_Time (default 9:00:30 on / 10:00:00 off), Cycle_Time (1800 s on / 3600 s off).
  • Programming via SWD (OpenOCD) or USB (UF2 bootloader): press Reset and BOOT, release Reset first then BOOT, drag-and-drop the .elf into the mass-storage device.
  • While programming, power the board through the Raspberry Pi’s power port because flashing resets the RP2040 and interrupts power.
  • The soft-shutdown script requires a Raspberry Pi reboot to take effect; without rebooting, the configuration will not apply.
  • Theoretical maximum output current is 3 A; with a fully charged 3.7 V Li battery, the practical limit is about 2 A.

Commands and examples – verify before use:  

sudo raspi-config
sudo minicom -D /dev/ttyS0
openocd -f interface/raspberrypi-swd.cfg -f target/rp2040.cfg -c "program ./Power_Management_HAT.elf verify reset exit"

Notes and version constraints

  • Li-ion and Li-po batteries can cause fire, personal injury, or property damage if mishandled; never connect them in reverse polarity, avoid inferior chargers, and do not mix old and new cells.
  • Battery cycle life is limited; replace when max cycles are reached or after two years of service, whichever comes first.
  • Programming over SWD resets the RP2040 and interrupts power supply—during this time, power the Raspberry Pi through its own power port.
  • The OpenOCD build is version-sensitive (branch rp2040-v0.12.0); differences in SDK or driver versions may cause failures.
  • Demo timing values are defaults and should be adjusted to the intended use before deployment.
  • When using a Li battery, confirm that the battery specification matches the board and that the cell has been aged and tested by the manufacturer.

Source and revision record

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