Testing the GeoMCU Hardware

Tools Needed

  1. Multimeter (to check voltages)

  2. Oscilloscope and Waveform Generator (we typically use an Analog Discovery for both)

  3. The GeoMCU board

  4. USB-to-serial cable

  5. serial terminal software installed (to communicate via the serial terminal)

  6. Power supply: 12V jack with adapter

Individual PCB Testing

Note

Version 2.7 boards are tested as described here. Version 2.9 boards will require the gain to be set before use, so modify this process accordingly.

  1. Voltage Checks

    • The ESP should briefly flash blue when powered on. If it does not, do not continue testing.

    • AGND and DGND should both be 0 V.

    • 12V should read whatever voltage is supplied.

    • 5V is the switching line (should measure around 5 V).

    • 3.3V powers most logic components.

    Check the analog reference voltages as well:

    • AGND, 3.3 V REF, and 1.65 V REF.

  2. Amplifier Check:

    • The pin to the right of the geophone connector is the amplifier input (labeled AMP)

    • The inner center pin of the connector should be the output going to the ADC.

  3. Dynamic Checks

    (Performed after flashing the firmware and initial setting up the board.)

    • Connect to the board via USB-to-serial.

    • Run the adc dump command in the serial terminal.

    • Tap the geophone and observe data changes.

  4. Testing Gain:

    Use the Analog Discovery’s wave generator and scope to observe where the signal clips.

    Steps:

    • Connect to the board over serial.

    • Set the gain using e.g., gain 10 (replace 10 with your desired value).

    • Check the configured gain using gain without a number — this verifies the math behind the gain setting.

Board Grading

  • Hardware bugs with the v2.7 boards make them unstable at high gain values depending on part tolerances. So, we separate them into two grades:

    • A-Grade boards will not clip until very high gain values.

    • B-Grade boards show instability or clipping at relatively lower gain (e.g., 10–12).

If your board passes all of the above, testing is complete. Otherwise, further debugging may be required.

Power Supplies Check

(Insert power rail verification steps or table here, if available.)

Flash Firmware

Follow the instructions in Flashing to the PCB to install and run the firmware on the sensor board.

Gain Checking

  1. In your serial terminal, after confirming that you can view data, enter the adc command to switch to the ADC configuration menu

  2. If you are unsure about available commands at any point, type help in the terminal.

Note

Quick Functional Check

To quickly verify vibration sensing:

  1. Connect a geophone to the board.

  2. Shake or tap the geophone while monitoring one of the following:

    • MQTT data (requires the MQTT Broker and the on-board ADC)

    • Wired analog output (requires an oscilloscope)

    • Output from adc dump (requires only serial connection and the on-board ADC)

The signal should vary significantly (swinging between min and max values) when the geophone is moved. If the output remains flat, the board is not properly sensing vibrations.

Networked Geophone Testing

(Add procedures for multi-node or MQTT-based geophone testing here.)