Electro

Overview

This firmware uses the particle photon to create a wi-fi voltmeter.

Usage

2 cloud variables are exposed: voltage and maxvoltage.

# Calculate and display maximum input voltage
particle variable get <photon-name> maxvoltage

# Read current voltage difference between positive and ground probes
particle variable get <photon-name> voltage

Hardware

Parts used:

• Particle Photon (x1)
• 82k ohm 1% tolerance resistor (x1)
• 10k ohm 1% tolerance resistor (x1)
• (Optional) Breadboard (x1)
• (Optional) Jumper wires (x4)

Wiring Diagram Example:

Firmware

The photon analog input pins can take an input voltage of between 0 and 3.3 volts, and are 12bits giving a 4096 resolution. In order to reduce the input voltage to prevent damaging the photon, a voltage divider circuit is used. Depending on the resistor values used, the maximum safe input voltage in calculated.

• vPin variable can be changed to correspond to using photon inputs A0-A5.
• vPow variable can be adjusted based on individual photon reference voltage.
• r1 can be adjusted if resistor 1 (82k ohm) is changed.
• r2 can be adjusted if resistor 2 (10k ohm) is changed.