TABLE OF CONTENTS

• Overview
• Enabling Battery Power
• Disabling Battery Power
• Monitoring and Protection
  • Battery Power Output Monitoring
  • Battery Power Output Protection
  • USB Power Output Monitoring
  • USB Power Output Protection
  • USB Power Errata

Overview

Battery power to the HOST and PAN ports is not enabled by default. You can control battery power using the provided systemd services.

Enabling Battery Power

To enable battery power for each port, run:

sudo systemctl start vbat-power@host
sudo systemctl start vbat-power@1
sudo systemctl start vbat-power@2
sudo systemctl start vbat-power@3
sudo systemctl start vbat-power@4

Disabling Battery Power

To disable battery power for each port, run:

sudo systemctl stop vbat-power@host
sudo systemctl stop vbat-power@1
sudo systemctl stop vbat-power@2
sudo systemctl stop vbat-power@3
sudo systemctl stop vbat-power@4

Monitoring and Protection

Battery Power Output Monitoring

Monitoring Method: Each battery power port (HOST and PAN1–PAN4) is monitored via an internal ADC.

Status Reporting: SPI ADC read commands will be inserted as needed, and a kernel driver is in progress to expose these settings via IIO and/or hwmon interfaces.

Battery Power Output Protection

Overcurrent Threshold: An output current exceeding 4.5A (+/-10%) triggers an overcurrent fault.

Fault Behavior: When triggered, a load switch toggles an input on an I2C expander. The fault signal remains active for at least 100ms, after which the load switch will automatically retry until the overcurrent condition is cleared or a thermal shutdown occurs.

USB Power Output Monitoring

Monitoring Method: The output current of each USB 5V power port (PAN1–PAN4) is also monitored via an internal ADC.

Status Reporting: As with battery power, SPI ADC read commands will be added and a kernel driver is under development to expose these via IIO and/or hwmon interfaces.

USB Power Output Protection

Overcurrent Threshold: An output current exceeding 2.2A (+/-10%) triggers an overcurrent fault.

Fault Behavior: The fault signal persists for at least 100ms after an overcurrent is detected. The load switch then automatically retries until the overcurrent condition is removed or a thermal shutdown occurs.

USB Power Errata

Default State: USB power is initially enabled for all PAN ports, but the corresponding usb-power services are not started by default.

Workaround: To align the service state with the actual port state, enable the services at startup:

sudo systemctl enable usb-power@1
sudo systemctl enable usb-power@2
sudo systemctl enable usb-power@3
sudo systemctl enable usb-power@4