hello;
I am using at91sam7x256's USART1 to interface a GPS IC (FC oncore) which has a Serial port interface. Because both devices use 3.3V, there is no level convertor IC between them (such as MAX232).
The problem is that the received data is similar to what it should be, but obviously it has some errors. any idea why USART1 receives wrong data?
Thanks

OK, I solved it myself. the problem was the fact that the GPS IC could not sink enough current (both pin current and current of internal pull-up resistor of sam7x256) and because of that, logic low of Rx (data that is received by sam7x256) was almost 1V. so, I turned off the pull-up resistor and now it works fine.