RMIS-1 Connections and Interfacing


RMIS (Remote Monitoring IoT System), includes the following connections:

  • PCB DC input (10v to 15v).  15V MAX
  • UART for Flashing code or external board monitoring & control via serial
  • I2C Expansion Interface, for adding other devices
  • Current and Voltage Monitoring (4 Channels – High Side Sensing)


  • The Current Channel connectors are quality 5mm spacing, 32A Insulated Screw Terminal Blocks – with a cable diameter range of 0.5 mm² to 4 mm². This equates to a conductor cross section of 20 to 10 AWG.
  • These connectors are not pre-soldered to the SDK PCB, so enabling the option to solder the cables directly, or use the terminal blocks.
  • Standard 2.4mm pitch header pins are provided for I2C and UART.



DC PCB Input

This is used to power the board.  The on-board LDO regulators provide the 3V3 and 5V, which power the ESP8266 and other devices.

Please note that the maximum input voltage is 15V.  This is is capped by the LDO input voltage rating.



This is used to easily flash the RMIS ESP8266 from your preferred IDE (such as Arduino, Visual Code, Platform IO etc.)

Connections and further information on the UART header can be found here.

Pin Connections

  • 1 – 3V3
  • 2 – RXD
  • 3 – TXD
  • 4 – DTR
  • 5 – RTS
  • 6 – GND


  • You will need to connect the UART TX to RMIS RX, and UART RX to RMIS TX.
  • You can use the UART header for powering the board ESP8266 (3V3 only).  However, the current sensing and ADC uses 5V, so this will not work.
  • As RMIS uses the DTR and RTS, you do not need to put the board in to flashing mode.  It is done automatically when programming.



This is used to connect RMIS to additional I2C devices, peripherals, sensors etc.

The connector also exposes GPIO16.   This can be used as an input or output (3V3), or for 1-Wire devices such as a DS18B20 Digital Temperature Waterproof Sensor Probe.

Pin Connections

  • 1 – 3V3
  • 2 – SDA
  • 3 – SCL
  • 4 – GP16
  • 5 – GND


  • For external 1-Wire sensor connections, you can use the 3V3, GP16 and GND (Ground).
  • GP16 has an on-board pull-up resistor (4k7), to 3V3.
  • Both I2C SDA and SCL, have an on-board pull-up resistor (10k), to 3V3.
  • The on-board temperature sensor (MCP9808), is using address 0x16.


Current and Voltage Monitoring

These four connections are used to provide isolated current and voltage monitoring

  • The two connections on each channel are used for current monitoring.  Depending on which way the current flow, displays either positive or negative current.
  • The positive on each channel, is used to monitor the channel voltage, with respects to the common ground.


  • RMIS is based on High Side Sensing.  So the + needs to go onto the positive supply, or feed, and the load, or output, on the – to supply negative.
  • Should you wish to separate the current and voltage monitoring, a 0R link is provided on each channel input. The resistor pad is then available to provide a separate voltage input.
  • The potential divider on each channel can be changed to scale the required input voltage range.  By default, two versions of RMIS SDKs are available.  RMIS-1-30 (0-30V) and RMIS-1-60 (0-60V).



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