Power Management HAT

Power Management HAT Power Management HAT for Raspberry Pi integrate Arduino MCU and RTC

Information Categories: Raspberry Pi Brand: Waveshare

Description Features --- Interfaces RPiUART

Related products {{{related}}}

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	Arduino (ATmega328P) side
GPIO of Pi	GPIO of Arduino	Functions Description
GPIO20	PC3	Input: Raspberry Pi shutdown if the pin is High detected. You should set it to Low when working	Output: If it is set to High, Raspberry Pi will shutdown. You should set it to Low when Raspberry Pi is on.
GPIO21	PD7	Output: If this Pin is high, it means that Raspberry Pi is working. It turns to Low if Raspberry Pi is shutdown.	Input: If Raspberry Pi is working, it will be detected as High, and it will be detected to Low if Raspberry Pi is shutdown.

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

The Software is divided into two parts. You need to first configure the Raspberry Pi. Then download the control codes (firmware) to the Power Management HAT by Arduino IDE. The different examples feature different function.

Software setup (Pi)

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

• Download shell script

sudo wget https://raw.githubusercontent.com/waveshare/Power-Management-HAT/master/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 [File:Power-Management-HAT.7z |Downoad the Package]. 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 (firmware) 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)

Hardware Configure

• Attach the Power Management HAT on the 40PIN GPIO of Pi directly
• Tthe Management HAT will supply the Raspberry Pi by the Management HAT as well, you need to connect external power adapter.
• To power the devices(Management HAT and Pi), you can choose one method from them:
  • You can connect 5V power adapter to the USB interface of Management HAT for powering
  • You can also connect the battiers to the DC interface (7V~28V) for powering or other DC power supply.
  • If you connect both the USB or the DC power adapter (batteries), the Management HAT will use the USB by default.

Indicators

• POWER: The Power led is used to indicator the power status of Pi. If the led blinks when pressing and after releasing, it means that the power is low for Pi
• STATUS: This led is used to indicates the working status of Management HAT
  • No firmware/Normal: Blinking every 5s
  • Solid light when pressing buttong or starting/shutdow
  • Abnormally starting: Blinking thrible time with 1s invertal.

Examples

Several examples are provided, you need to download them to the Power Management HAT to feature the differnt contorl function.

ButtonBoot

This examples is used to control the power of Pi by button.

• Open Arduino IDE, and open ButtonBoot examples (File->Examples -> PowerManagementHAT->ButtonBoot)
• Compile and download the examples to Power Management HAT

Expected function

• If Raspberry Pi is off
  • Press Power button to start Raspberry Pi
• If Raspberry Pi is on
  • 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 also modify the firmware before you download it to the Management HAT, the adjustable parameters are:

Parameters	Description	Default value
SHUTDOWN_TIME_MS	The shoftware shutdown threshold: If you long press the PWR button for [threshold] ms, the Pi shutdown	2000
CUT_POWER_TIME_MS	The cut-off threshold: if you long-press the PWR button for [threshold] ms, the power of Pi is cut-off	8000
CURRENT_CHECK	Disbale/Enable the current checking, if you enable it, the board will detect the working status of Pi by the current.	false
CURRENTTHRESHOLD_MA	If working current of Raspberry Pi is less than this threshold value, Raspberry Pi is determined as shutdown. Default disabled	350

MeasureCurrent

• Open Arduino IDE, and open MeasureCurrent examples (File->Examples -> PowerManagementHAT->MeasureCurrent)
• Compile and download the examples to Power Management HAT
• If Raspberry Pi is off
  • Press Power button to start Raspberry Pi
• If Raspberry Pi if on
  • 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 modify the threshold value of long-press time:

Parameters	Description	Default value
SHUTDOWN_TIME_MS	The threshold of (press time) software shutdown	2000
CUT_POWER_TIME_MS	The threshold of (press time) power cut off	8000

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 is off
  • Press Power button to start Raspberry Pi
• If Raspberry Pi is on
  • 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

Parameters	Description	Default value
SHUTDOWN_TIME_MS	The threshold of (press time) software shutdown	2000
CUT_POWER_TIME_MS	The threshold of (press time) power cut off	8000
ON_VOLTAGE_VOLT	The min voltage to start Raspberry Pi	6.6
OFF_VOLTAGE_VOLT	The threshold of Low-voltage shutdown	6.3
FORCE_OFF_VOLAGE_VOLT	threshold of emergency shutdown	5.8
LOW_VOLTAGE_TIME_MS	Waiting time of low-voltage shutdown	30000
OVERRIDE_TIME_MS	The delay time of low-voltage continuation	3600000

【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.

	1S (DO NOT Support)	2S (1S*2)	3S(1S*3)	4S(1S*4)
ON_VOLTAGE_VOLT	3.3	6.6	9.9	13.2
OFF_VOLTAGE_VOLT	3.15	6.3	9.45	12.6
FORCE_OFF_VOLTAGE_VOLT	2.0	5.8	8.7	11.6

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:

Parameters	Description	Default value
WAKE_UP_START_HOUR	Start time-hour	8
WAKE_UP_START_MINUTE	Start time-minute	30
SLEEP_START_HOUR	Shutdown time-hour	18
SLEEP_START_MINUTE	Shutdown time-minute	30

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.

Difference bettween two examples

Examples	PowerOnPeriodicallyOnTimer	PowerOnPeriodicallyOnAlarm
Difference	Periodly power on Raspberry Pi by timer	Periodly power on Raspberry Pi by RTC alarm
Advantage	Simple	High precision (compare with timer)

PowerOnPeriodicallyOnTimer

Parameters	Description	Default value
PERIODIC_TIMER_TIMEBASE	Unit of periodic	eTB_MINUTE
PERIODIC_TIMER_VALUE	Periodic value	10
RPI_STAY_AWAKE_TIME_MS	Working time	60000

PowerOnPeriodicallyOnAlarm

Parameters	Description	Default value
RPI_WAKE_UP_CYCLE _MINUTE	Periodic value	10
RPI_STAY_AWAKE_TIME _MS	Working time	60000
CURRENT_THRESHOLD_MA	Threshold of current (if working current is less thant this value, Raspberry Pi is determined to be in shutdown status)	110

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

Parameters	Description	Default value
PERIODIC_TIMER_TIMEBASE	Periodic unit	eTB_MINUTE
PERIODIC_TIMER_VALUE	Periodic value	5
RPI_STAY_AWAKE_TIME _MS	Working time	60000
WAKE_UP_START_HOUR	Start time-hour	8
WAKE_UP_START_MINUTE	Start time-minute	30
SLEEP_START_HOUR	Shutdwon time-hour	18
SLEEP_START_MINUTE	Shutdown time	30

Resources

Documents

• Schematic

Demo codes

• Arduino Examples (firmware)

Datasheet

• ATmega328P Datasheet
• CAT24C23
• CP2102
• MAX9938.pdf
• MP1584.pdf
• PCF8523.pdf
• RT9193.pdf

FAQ

...

Supports

Contact us Working hours: 09:00-18:00 (UTC+8 Monday to Saturday)