I2C interfacing with several LCD with same address

Discussion in 'Embedded Systems and Microcontrollers' started by gdalmeida, Feb 11, 2015.

  1. gdalmeida

    Thread Starter New Member

    Feb 11, 2015
    Hi guys,

    I am planning on designing a board with 10+ LCDs I2C driven. I would like to hear what you guys can suggest for architecture. I was thinking about using an I2C multiplexer so I can use only one micro port.

    This is the LCD: http://www.buydisplay.com/default/0...module-64x32-pixel-ssd1306-i2c-white-on-black

    This is the multiplexer PCA9547. Do you think this is the best way to go or I am overlooking any other option.

  2. MrChips


    Oct 2, 2009
    I would choose 3-wire SPI and use CS# to select the display.
  3. Shagas

    Active Member

    May 13, 2013
    If the multiplexer doesn't work out or if you can't get hold of them then perhaps you can dedicate a whole 40 pin micro to this task and bitbang all of your I2c ports to the displays. Then have your main micro talk to this controller micro through I2c bus.
    I'm not sure if the lack of slew rate limitation will have an effect on your communication with the lcds. You would have to test that out.
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    I don't think that is a good choice for a display as everything sits on the same address. You may want to look into a "standard" paralel display and interface it with something like an I2C port expander. While I have only seen these addressable up to 8 devices (after a 30 sec search) you could still use that as an address enable so they all still sit on the same address (or be clever and put groups of 4 to reduce the control lines to 3).

    Phillips does make I2C switches to separate interfaces.

    Depending on how the display works as a slave you may be able to simply multiplex the clock line into 10 lines.
  5. shteii01

    AAC Fanatic!

    Feb 19, 2010
    There is no point using i2c if all the devices on i2c bus use the same address.