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?

 

Originally posted by markrod@Jun 9 2006, 03:39 AM
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?

[post=17654]Quoted post[/post]​

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

or

TI Dual Schmitt Trigger