UART interface help

Discussion in 'The Projects Forum' started by markrod, Jun 9, 2006.

  1. markrod

    Thread Starter New Member

    Jun 3, 2006
    Hi! Im a newbie trying to interface a GSM module with my zilog microcontroller. Apparently they two dont have the same voltage levels for their UART. the GSM module operates at 2.65V while my Zilog microcontroller operates at 3.3V. Can anyone help me or give me advice on how to go about with this?
  2. Papabravo


    Feb 24, 2006
    I think you can use one of the new logic families which have a large Vcc range, TTL thresholds, and have inputs which tolerate overvoltage. Here is the idea. To drive the phone use a part with Vcc=2.65 Volts which will tolerate a 3.3 Volt Input. To drive the Zilog micrprocessor use the same part with Vcc = 3.3 Volts. The part must have TTL thresholds for this to work. Here are some parts that might work:

    OnSemi Dual Schmitt Trigger


    TI Dual Schmitt Trigger