What is it?

The CircuitSetup ATM90E32 Split Single Phase Energy Meter can monitor the energy usage in your entire home in real time. It can easily be hooked up to an ESP8266 or ESP32 to wirelessly transmit energy usage data into a program like EmonCMS. It can also be used to monitor solar power generation to keep track of how much power you are making.

The ATM90E32 IC from Microchip is versatile and affordable. We’ve put it on a 40x50mm PCB and connected all the useful bits, so it’s easy to hook up to an ESP or Arduino board of choice, current transformers, and an ac transformer (for voltage & powering the board). From there, all you have to do is load the software on your MPU via the Arduino IDE to start seeing how much power your house is using!

With the Split Single Phase Energy Meter you can:

• Save Money!
  • See exactly how much money is being spent on energy in real time
  • Find appliances that are using too much electricity
• View & Gather Energy Data
  • View the energy usage of your entire home
  • Or track solar power generation
  • Review and graph historical energy data
  • View usage data in the EmonCMS Android or iOS apps
• Be Informed!
  • Independent of your power company's meter
  • Set up alerts for over or under usage
• Not spend a ton on energy monitoring!
  • Built to be inexpensive, but very accurate
  • Costs hundreds less than some other solutions

Features:

• Uses the Microchip ATM90E32AS
• Samples 2 current channels & 1 voltage channel (expandable to 2 voltage)
• Calculates:
  • Active Power
  • Reactive Power
  • Apparent Power
  • Power Factor
  • Frequency
  • Temperature
• Uses standard current transformer clamps to sample current
• Includes built-in buck converter to power ESP8266, or ESP32
• 2 IRQ interrupts, and 1 Warning output
• Energy pulse output (pulses correspond to 4 LEDs)
• Zero crossing output
• SPI Interface
• Measurement Error: 0.1%
• Dynamic Range: 6000:1
• Gain Selection: Up to 4x
• Voltage Reference Drift Typical (ppm/°C): 6
• ADC Resolution (bits): 16
• Compact size at only 40x50mm

Why did you make it?

There were no high resolution energy meters on the market for single split phase homes.

What makes it special?

This energy meter allows makers with single split phase power to see how much energy they are using in real time without spending a lot of money to do so.

What you’ll need:

• Current Transformers:  SCT-013-000 100A/50mA (select the version of the board with phono connectors) or Magnelab SCT-0750-100 (must sever burden resistor connection on the back of the board since they have a built in burden resistor). Others can also be used as long as they're rated for the amount of power that you are wanting to measure, and have a current output no more than 600mA.
• AC Transformer: Jameco Reliapro 9v
• An ESP32 (ESP8266 or anything else that has an SPI interface & recommended wifi)
• Jumper wires with Dupont connectors, or perf board to connect the two boards.
• EmonCMS (shown in pictures), ThingSpeak, ESPHome/Home Assistant, or similar
• Library for the ATM90E32 and other software examples are on the Github page. Also see the ESPHome ATM90E32 sensor.