Temperature sensor

Discussion in 'The Projects Forum' started by edmundopt, Aug 27, 2013.

  1. edmundopt

    Thread Starter Member

    May 4, 2011

    I have a project with multiple mcu, they all comunicate via I2C, problem is that I nedd to log temperature with four of the mcu. The temperature sensor will be connected to the mcu by a 4 meters cable, I was thinking of I2C buffers for the cable and I2C sensors, problem is, the mcu only have one I2C port.
    Any sugestions alternatives to a temp sensor over 4meters wire, maybe I can read it with ADC port?
  2. MaxHeadRoom


    Jul 18, 2013
    Isn't the I2C multi-drop?
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Depending on the environment an RS232 connection may be more robust, as I2C was designed to talk to devices very close (on the same PCB typically).

    But to just get an extra I2C bus you can just "bit bang" two pins to make another bus... No special hardware required. Examples may be found at the website "Google" and many others under "soft I2C."
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Just use a good analogue sensor like the LM35 and connect the voltage output of the sensor to the micro's ADC pin. A cable length of 4 metres is fairly insignificant provided you use shielded cable and/or put a decent sized cap on the ADC pin to ground.
    wayneh likes this.