I2C & GPIO control to 24-Channel DPDT Relay board

Hello NCD support team,
Our R&D team is interested to purchase one of your product “24-Channel DPDT Signal Relay Shield + 8 GPIO with IoT Interface”.
But there are some inquires that we are unsure about I2C port and 8GPIO Pins. Here are some questions to raise:

  1. Is this relay board can be controlled by I2C interface from our own MCU board, two way communication “Send signal and on/off the relays from our end”?
  2. What is the Built in I2C port usage for? Is it only for expending the I2C boards or can be used as control pins?
  3. how to connect to the 8-GPIO pins and how to use as? Do we need GP-IP board to communicate with them, or just can be used as control pins?
  4. Either I2C or 8-GPIO pins can be used with Main Controller boards for Relay control?
  5. Our purpose is to use our MCU to control the states of 24-Relays via I2C or GPIO pins. Can that be done?

Thanks for the support!


I have answered your questions accordingly below:

  1. This will depend on what your MCU board is and what capabilities it has.

  2. Yes the I2C port is used for expansion purposes.

  3. The GPIO lines can be controlled high/low(5VDC) or they can be used to monitor Dry Contact closure or external 0-5VDC levels.

  4. The board you specified has an IoT interface which means you can install one of our IoT interface compatible MCUs such as the ESP32 module. If you wish to control the lines from an external MCU via I2C then I would recommend this product instead:
    This board has an I2C input connection so it can be controlled via I2C from an external MCU.

  5. Yes, if your MCU has I2C connection then it can control the relays on the board linked in answer 4.

Thank you,
Travis Elliott