Raspberry Pi Power Management HAT User Guide

Instruction

The Power Management HAT is a smart power bank designed for Raspberry Pi. With the embedded Arduino MCU and RTC, the HAT features auto power management function which allows the Pi to work more power-efficient and more safely.

Features

• Standard Raspberry Pi 40PIN GPIO extension header, supports Raspberry Pi series boards
• Onboard ATmega328P MCU, supports Arduino programming
• Onboard PCF8523 RTC chip, provides precise RTC information
• Onboard CP2102 UART converter, for UART communication or ATmega328P programming
• User-defined button, can be used for Raspberry Pi start up, safely shutdown, or other customized function
• Protection circuits such as: power supply anti-reverse, counter current proof, etc. ensures stable and safe operating
• Voltage/current monitoring circuit, monitors the Raspberry Pi operating voltage and current in real time
• Comes with development resources and manual

Specification

• Controller: ATmega328P-AU
• Communication interface: UART + GPIO
• Baudrate: 115200bps by default (programmable)
• Power supply interface: USB port or PH2.0 connector
• USB power input voltage: 5V
• PH2.0 power input voltage: DC 7~28V (regulated power supply or lithium battery)
• Embedded circuits: power supply anti-reverse, counter current proof, voltage monitoring, current monitoring
• Mounting hole size: 3.0mm

Working principle

The ATmega328O connect to Raspberry Pi by 2 GPIO. These pins are defined by firmware.

Raspberry Pi side

• Power on: GPIO21 is set to High after powering on
• Power off: Keep detecting the status of GPIO20, if it is high, Raspberry Pi shutdown and set GPIO21 to Low after shutdown.

Arduino (ATmega328P) side

• Power on: Set PC3 to Low and power on Raspberry Pi. If PD7 is detected as High, it means that Raspberry Pi boots successfully.
• Power off: Set PC3 to High, Raspberry Pi shutdown after detecting it. Keep detecting the status of PD7, if PD7 is Low, it means that Raspberry Pi has shut down and it can cut off the power of Raspberry Pi.

Preparation

Software setup (Pi)

Open terminal of Raspberry Pi and set system-shutdown script.

• Download shell script

sudo wget https://github.com/waveshare/Power-Management-HAT/Power-Management-HAT-Setup.sh

• Set the permission of the script

sudo chmod a+x Power-Management-HAT-Setup.sh

• Run the script

sudo ./Power-Management-HAT-Setup.sh

Press Y when you get the prompt "Would you like to reboot now? y/n" to reboot Raspberry Pi. 

Software setup (PC)

• Install Arduino IDE: Please install Arduino IDE to your Windows PC and remember the installation path.
• Install Power Management HAT package

Download package form Github. Copy the PowerManagementHAT folder (You may need to unzip it firstly) to hardware directory which is under the installation directory of Arduino IDE.

• Setup Arduino IDE

Restart Arduino IDE.

Connect USB interface of Power Management HAT to PC.

Select the correct port

Select Power Management HAT device

Finally, examples can be found from File->Examples->PowerManagementHAT

Hardware connection

Attach Power Management HAT on Raspberry Pi. Then you can power Raspberry Pi by the Power Management HAT without an external power adapter.

Power management is powered by one of the ways below:

• You can power Power Management HAT by USB. If you connect batteries pack and plug USB power adapter at the same time, Management HAT is powered by the USB power adapter by default.
• You can power Power Management HAT by batteries pack, or use other DC power supply. (Voltage range:7V~28V)

Examples

ButtonBoot

• Open Arduino IDE, and open ButtonBoot examples (File->Examples -> PowerManagementHAT->ButtonBoot)
• Compile and download the examples to Power Management HAT
• If Raspberry Pi has been shutdown
  • Press Power button to start Raspberry Pi
• If Raspberry Pi has been started
  • Long-press Power button for 2s~8s, Raspberry Pi will be first software shutdown and then cut off power
  • Long-press Power button for more than 8s to directly cut off power of Raspberry Pi.

You can adjust it:

MeasureCurrent

• Open Arduino IDE, and open MeasureCurrent examples (File->Examples -> PowerManagementHAT->MeasureCurrent)
• Compile and download the examples to Power Management HAT
• If Raspberry Pi has been shutdown
  • Press Power button to start Raspberry Pi
• If Raspberry Pi has been started
  • Long-press Power button for 2s~8s, Raspberry Pi will be first software shutdown and then cut off power
  • Long-press Power button for more than 8s to directly cut off power of Raspberry Pi.
• Open serial monitor, the working current of Raspberry Pi are printed to serial port.

You can adjust

MeasureVoltage_ShutdownInLowVoltage

• Open Arduino IDE, and open MeasureVoltage_ShutdownInLowVoltage examples (File->Examples -> PowerManagementHAT->MeasureVoltage_ShutdownInLowVoltage)
• Compile and download the examples to Power Management HAT
• If Raspberry Pi has been shutdown
  • Press Power button to start Raspberry Pi
• If Raspberry Pi has been started
  • Long-press Power button for 2s~8s, Raspberry Pi will be first software shutdown and then cut off power
  • Long-press Power button for more than 8s to directly cut off power of Raspberry Pi.
• Open serial monitor, the working current of Raspberry Pi are printed to serial port.

You can adjust

【Note】:

When the voltage of batteries is less than the OFF_VOLTAGE, if you press the Power button in 30000ms (LOW_Voltage_TIME_IN_MS), Raspberry can keep working for 3600000ms (OVERRIDE_TIME_MS). During this time, once the voltage is less than 5.8V (FORCE_OFF_VOLTAGE_VOLT), Management HAT will cut off Raspberry Pi immediately; Once the volage reach to On_VOLTAGE, the Raspberry Pi will be powered again.

You can measure the capacity of batteries by their voltage. For a single battery, the full voltage is about 4.2V, the batteries may be damaged if its voltage is less than 3.0V.

If you connect batteries for power, you should make sure that the whole voltage of the batteries pack is larger than 5V. The batteries pack we provided allows 2 18650 batteries at the same time. The table below is for reference.

PowerOnInAPeriodTime

• Open Arduino IDE, and open ButtonBoot examples (File->Examples -> PowerManagementHAT->PowerOnInPeriodTime)
• Compile and download the examples to Power Management HAT
• Raspberry Pi will be started in a certain period.

You can adjust:

PowerOnPeriodcallyOnTimer

• Open Arduino IDE, and open ButtonBoot examples (File->Examples -> PowerManagementHAT->PowerOnPeriodcallyOnTimer/PowerOnPeriodcallyOnAlarm)
• Compile and download the examples to Power Management HAT
• Raspberry Pi will be started periorlly.

PowerOnPeriodicallyOnTimerInAPeriodTime

• Open Arduino IDE, and open ButtonBoot examples (File->Examples -> PowerManagementHAT->PowerOnPeriodicallyOnTimerInAPeriodTime)
• Compile and download the examples to Power Management HAT
• Raspberry Pi will be power on periodly in certain time

Documents

• Schematic
  

Demo codes

• Arduino Examples
  

Datasheet

• File:ATmega328P datasheet Complete.pdf
• File:CAT24C23.pdf
• File:CP2102.pdf
• File;MAX9938.pdf
• File:MP1584.pdf
• File:PCF8523.pdf
• File:RT9193.pdf

To：

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Email(support)

services01@spotpear.com