Voltage Cycle Test with PPK2 and ESP32-S3

Overview

This project automates the power cycling of an ESP32-S3 device using the Nordic Power Profiler Kit 2 (PPK2) to evaluate its performance under varying voltage conditions.

The project includes scripts to control the PPK2 and monitor the ESP32-S3 over serial communication to verify successful boot and operational stability.

The current code is expecting the Adafruit WipperSnapper firmware to be running on the Device Under Test (DUT), and was written to test the loss/corruption of secrets.json in a fatfs partition when running on battery power after random number of reboots.

Requirements

Hardware

• Nordic PPK2: Used as a programmable power supply and for measuring power consumption.
• ESP32-S3 Board: Device under test.
• Computer: To run the python script(s) and control the PPK2 and serial communication.
• USB Interruptor: To manage isolating the power between USB VBUS and the Device Under Test while still allowing USB Communications with PC.

Software

• Python 3.8+: Required to run the scripts (assume 3.12 or something more modern).
• IRNAS PPK2 API Library: ppk2-api-python
  • While available with pip install ppk2-api, there may be things worth picking up in the PRs by using from git:
  • Clone and install using the following commands:

    git clone https://github.com/IRNAS/ppk2-api-python.git
    cd ppk2-api-python
    echo 'checkout a PR branch now or in the future and it will be available immediately'
    pip install -e .

• PySerial: For communication with the ESP32-S3. (Probably already available)

  pip install pyserial

• Logging Module: Configured to record test logs in a voltage_test.log file.

Setup

Fritzing diagram:

0. Disconnect all usb cables + depower all devices.

1. Connect Hardware:

   • Connect the ESP32-S3 to the PPK2, I'm using the Battery input on an Adafruit QTPY ESP32S3 (n4r2) with Lipo BFF, using the battery input pins for the PPK2 connection.
     • Alternatively use an appropriate connection method to power the board. e.g. A Metro board (debuggable) with StemmaQT MAX17048 taking the ppk2 supply as battery and then a two female jst-ph plugged cable (or jumper cables) from the MAX17048 second port to the Metro power in (battery jst).
   • Use a USB Switchable Breakout a.k.a. "Isolator" I used this one to disconnect the USB VBUS from the computer and the ESP32s3/DUT.
   • Ensure ground connections between all components (should be now).
   • If using logic pins of PPK2 then include a vRef and ground connection to the 3v3 + Gnd from QTPY to the PPK2 logic pins labelled VCC + GND

2. Configure COM Ports:

   • Edit the Python scripts to set the correct COM ports for both the PPK2 and ESP32-S3 connections.
   • Replace PPK2_COM_PORT and SERIAL_PORT with your specific port numbers (e.g., COM34 for PPK2 and COM36 for ESP32-S3).

Scripts

• Main Voltage Cycle Test Script: This script powers on the DUT, runs through multiple voltage levels, and checks if the ESP32-S3 boots and connects to WiFi successfully.

  • The voltage starts at 3.0V and decrements down to 2.8V with steps of 0.01V. The ESP32-S3 is tested for each voltage level.
  • Logs are saved in a file named voltage_test.log.
  • The power cycle test is repeated 50 times per voltage level.
  • Adjust the numbers to suite your needs, along with the conditionals for success+failure serial messages.

• Power Toggle Test Script: This script tests if the power from PPK2 is toggled on/off as expected. It cycles between 800mV, 1500mV, and 3000mV every 3 seconds, turning the device off for 2 seconds between cycles.

Usage

1. Voltage Cycle Test Script

   • This script is used to evaluate the ESP32-S3 boot reliability under varying voltages.
   • Run the script using:

     python voltage_cycle_test.py

   • Logs and measurement data will be saved to CSV files for each cycle.

2. Power Toggle Test Script

   • The script helps verify if the power from the PPK2 is reliably toggling between the defined voltage levels.
   • Run the script using:

     python power_toggle_test.py

Example output (logging level changed to DEBUG):

Notes

• Ensure that the ESP32-S3 has time to settle after each power cycle.
• Logs and power measurements are saved to help analyze device behavior.
• The script retries connection to the ESP32-S3 serial port until it is successful, ensuring stable communication after power cycling.

License

This project uses the licenses of the respective dependencies and no others.

Acknowledgements

• IRNAS for providing the PPK2 Python API to automate power monitoring and logging.
• Adafruit for providing me with gainful employment and the hardware to play with such things.