Connect with us

Connecting a 5.0V UART to a 3.3V UART

Discussion in 'General Electronics' started by Susanne Fischer, Jun 16, 2004.

  1. Hi!

    I have a Microcontroller (Fujitsu MB90F347) running with 5.0V supply
    voltage and a bluetooth module (Zeevo 3001Z) with 3.3V. Now I want to
    connect them over UART.
    Usually I would connect them directly. But this might not be possible
    because of the different voltage levels.
    Is there a simple solution how to do that? Perhaps I could convert the
    signal twice using a MAX232 or similar. But as I wrote in a previous
    thread, this somehow doesn't work. But I don't know why not. Any idea?

    This brings me into serious trouble since I am not able to do further
    work on this whole stuff and I have to match some deadlines. I am
    really helpless because I just don't understand why this whole thing
    doesn't work...

    If anyone has an idea how to make communication possible, please help
    me!
    Thanks in advance,
    Susanne Fischer
     
  2. Quack

    Quack Guest

    Hi!
    I havent tried this, but it seems to make sense, it seems a simple
    approach :)

    The Fujitsu RX pin should be able to connect directly to the Zeevo 3v
    TX pin, and get a clear signal.

    The Zeevo RX pin should use a 2.5v zenner diode, to cut the incoming
    5v signal down the that voltage.
    One of them may be using 'inverted' comms, the other 'true'.

    You can use a couple of transistors and a few resistors to make a
    2-way inverter if necesary, i have done this before.

    I dont think using 2 MAX232 chips would help if 1 of them is opposite.


    Alex.
     
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-