Interfacing STM32F205RBT6 to max232

Discussion in 'General Electronics Chat' started by aamirali, Aug 1, 2014.

  1. aamirali

    Thread Starter Member

    Feb 2, 2012

    Can I interface directly max232 to STM32F205RBT6.
    I have given 5V to VCC of max232 & 3.3V to vcc of STM32.

    1. In datasheet of max232, it is given that Vih = 2V. So my 3.3V signal from STM32 will serve the purpose of txd

    2. In case of rxd, 5V signal will come from max232 to STM32. Are STM32 pins are 5V tolerant in case I configured them for uart?

    3. I have place 150ohm resistor each in between txd & rxd connections of both IC.
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    Why not use max3232 that works off 3.3V?
  3. cmartinez

    AAC Fanatic!

    Jan 17, 2007
    Try using the circuit that I've attached for you.
    It's a bi-directional level shifter interface, which means that it can be used either way as input or output.
    I've been using this circuit for a long time with my designs, and it's worked perfectly for me.
    I've also attached a PDF explaining how the circuit works.

    Regards, and have lots of fun with your project.