Setting up Safe Shutdown

PiPower Pro has two pins that are pre-configured to monitor the power status (referred to as sub-devices below) of connected devices, enabling remote power on, power off, and automatic safe shutdown when the battery is low.

Note

If the host running HassOS is set as a sub-device of PiPower Pro, it will also lose its functionality when the host shuts down, and remote power-on will not be possible.

  • Pin 42 and sensor entity binary_sensor.pipower_pro_sub_device_power_state read the current state of the device.

  • Pin 41 and entity switch.pipower_pro_sub_device_power control the sub-device power.

For example, let’s use PiPower Pro as a UPS power source for a Raspberry Pi, monitoring its status and automatically shutting it down safely when external power is lost and the battery level is low.

Step 1

Configure the Raspberry Pi.

Set the two Raspberry Pi pins to the Power Status Signal Pin and Shutdown Signal Pin respectively. This can be done through devicetree.

Insert the SD card with the Raspberry Pi system into your computer. In the root directory of the boot partition, find config.txt.

_images/sp230804_143344.png

Open it and add the following two lines at the end under [all].

dtoverlay=gpio-poweroff,gpiopin=17
dtoverlay=gpio-shutdown,gpio_pin=18

  • gpio-poweroff is the Raspberry Pi’s power on/off status. After successful configuration, the Raspberry Pi will set this pin high when powered on and pull it low when powered off.

  • gpio-shutdown controls the signal for shutting down the Raspberry Pi. After successful configuration, pulling this pin low will trigger the Raspberry Pi to shut down.

Step 2

  • Connect PiPower Pro’s pin 42 to the Raspberry Pi’s gpio-poweroff pin, here using pin 17.

  • Connect PiPower Pro’s pin 41 to the Raspberry Pi’s gpio-shutdown pin, here using pin 18.

Step 3

Now test if the above two signals are working properly.

Add two entities to the Dashboard:

  • binary_sensor.pipower_pro_sub_device_power_state

  • switch.pipower_pro_sub_device_power

If you add the Settings Card (see Add Card by Code Editor for instructions on adding cards), these two entities will be included, labeled as PiPower-Pro Sub Device Power State and PiPower-Pro Sub Device Power.

_images/sp230804_151521.png

You can use the former to check if the Raspberry Pi is working and the latter to power off the Raspberry Pi.

Note

PiPower-Pro Sub Device Power can only power off the Raspberry Pi. To power it on, you still need to supply power to the Raspberry Pi (i.e., turn on the main switch on the PiPower Pro Card).

Step 4

Next, configure automations to enable PiPower Pro to safely shut down the Raspberry Pi:

  1. Open the Home Assistant configuration page, click on “Settings” on the left sidebar, and choose “Automations.”

    _images/sp230804_170032.png

  2. Create a new automation.

    _images/sp230804_170118.png _images/sp230804_170148.png

  3. Click “Edit in YAML.”

    _images/sp230804_170218.png

  4. Replace the existing code with the following code.

    alias: Safe shutdown RPi
description: Turn off Raspberry Pi if no external power plug in and battery low
trigger:
  - platform: state
    entity_id:
      - binary_sensor.pipower_pro_external_power
    from: "on"
    to: "off"
  - platform: numeric_state
    entity_id: sensor.pipower_pro_a03846_battery_level
    below: 25
condition:
  - condition: and
    conditions:
      - condition: state
        entity_id: binary_sensor.pipower_pro_a03846_external_power
        state: "off"
  - condition: and
    conditions:
      - condition: state
        entity_id: switch.pipower_pro_sub_device_power
        state: "on"
action:
  - type: turn_off
    device_id: a0ee4e356c85c4f69f765ed72baad129
    entity_id: switch.pipower_pro_sub_device_power
    domain: switch
mode: single

  5. Click “Save.”

    _images/sp230804_170504.png

  6. Click “rename.”

    _images/sp230804_170527.png

  7. Go back one level. Now you should see the newly set automation.

    _images/sp230804_170710.png

Note

We need to create a few more automations. Refer to the previous steps to complete them all.

Save Power

alias: Save Power
description: Turn off if raspberry pi power off
trigger:
  - platform: state
    entity_id:
      - binary_sensor.pipower_pro_sub_device_power_state
    from: "on"
    to: "off"
condition:
  - condition: state
    entity_id: switch.pipower_pro_sub_device_power
    state: "off"
action:
  - delay:
    hours: 0
    minutes: 0
    seconds: 2
    milliseconds: 0
  - type: turn_off
    device_id: a0ee4e356c85c4f69f765ed72baad129
    entity_id: switch.pipower_pro_a03846_power_switch
    domain: switch
  - type: turn_off
    device_id: a0ee4e356c85c4f69f765ed72baad129
    entity_id: switch.pipower_pro_a03846_esp32_power
    domain: switch
mode: single

Sync Power Off RPi

alias: Sync Power Off RPi
description: Power Off Raspberry Pi is Switch Off
trigger:
  - platform: state
    entity_id:
      - switch.pipower_pro_a03846_power_switch
    from: "on"
    to: "off"
condition: []
action:
  - type: turn_off
    device_id: a0ee4e356c85c4f69f765ed72baad129
    entity_id: switch.pipower_pro_sub_device_power
    domain: switch
mode: single

Sync Power On RPi

alias: Sync Power On RPi
description: Power On Raspberry Pi is Switch On
trigger:
  - platform: state
    entity_id:
      - switch.pipower_pro_a03846_power_switch
    from: "off"
    to: "on"
condition: []
action:
  - type: turn_on
    device_id: a0ee4e356c85c4f69f765ed72baad129
    entity_id: switch.pipower_pro_sub_device_power
    domain: switch
mode: single

Step 5

We use a simulated low-power state to trigger the test:

  1. Open the SERVICES interface in Developer Tools.

    _images/sp230804_171500.png

  2. Find ESPHome: pipower_pro_simulate_low_power, enable it, and click the “Call Service” button.

    _images/sp230804_171721.png

You will see the PiPower battery light go off, and the battery level drop to 10% in the overview.

The Raspberry Pi will then shut down, and 2 seconds after it completes the shutdown, the PiPower Pro will power off, and the PWR light will go off.