CMIS ESP32 SDK v1 – Specification


CMIS (Current Monitor IoT Sensors), SDK Kit is based on an Espressif ESP32 WROOM and the board is designed to monitor four fully isolated DC currents up to 100A.

An I2C reversible 2.54mm header is provided in the middle of the board, which will allow an OLED display (such as a SSD1306 I2C), to be directly mounted / connected on the board.  OLED not included.

Large Quality Terminal Blocks are included, which are suitable for 20 AWG up to 6 AWG, 10mm².  These are not populated, so you may optionally solder cable tails directly to the PCB for higher currents.

Power for the board may either be provided via the Micro USB (for flashing, debugging etc.), and/or via a terminal block for normal operation.  DC input has a range of 7V, through to 15V maximum.

The CMIS SDK is suppled fully tested.


Below board example shows the four current terminal blocks and single DC power terminal block fitted – together with a standard SSD1306 OLED.


Large Quality Terminal Blocks suitable for 20 AWG up to 6 AWG, 10mm², Rated 52A 300V


CMIS v1 specification overview:

  • Espressif ESP32 WROOM
    • 2.4GHz Wi-Fi and Bluetooth LE MCU module, with dual core CPU
  • AT24C64 EEPROM
    • For storing parameters, calibration data, Logs etc.
  • 4 x Isolated Bi-directional Current Sensors AC/DC Maximum ±100A
    • ACS758 100A (ACS758LCB-100B-PFF-T), Hall Effect based, Linear Current Sensor
    • Large Quality Terminal Blocks suitable for 20 AWG up to 6 AWG, 10mm², Rated 52A 300V
  • ADC 12-bit Resolution
    • Using ESP32 Internal ADCs
  • CT Clamp Input
    • With or without Burden Resistor.
    • Suitable for popular SCT013 YHDC
  • On-board Temperature Sensor
    • NTC (range -40ºC to +125ºC)
    • Micro USB.  Uses the popular CH340 for ease of developing code, flashing and debugging
    • Arduino D1 Flashing and Programming Compatibility
    • No drivers normally needed
  • OLED Display Connections
    • I2C
  • DC Power LED (red)
  • RGB LED (ESP software code / firmware controlled)
  • SPI and I2C Connections
  • DAC Output
    • With LP/HP filter options (unpopulated R/C)
    • Configurable via 0805 place-holders and jumpers
  • On board 3V3 and 5V LDO Voltage Regulators
    • PCB 7-15V DC Input
  • PCB Size 100mm x 95mm



Important Foot Note.

These Wiki pages are MOVING to the GitHub Wiki.   Simply select a repository pertaining to the board and click Wiki.


Other Details

Further information on this product may be found in our downloads and Wiki pages.  Other technical information and code examples are also shared in our GitHub Pages.  Project information may also be found on

We value our customers and should you have any other questions, please feel free to contact us.

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