I've been trying to use the UART port for the past two days, and it's driving me crazy. Setting the baud rate to anything other than 200K stops the program from downloading. If you try it without re-downloading the firmware, you get this error:

If you try to download the program after re-downloading the firmware (which works fine), you get the error:


I've been trying to communicate with the Cortex, and nothing I try works. UART communication between two Cortexes works. If I set the baud rate as 200k on the cortex as well, I get either -1('y'), or random letters.

Did you follow Timothy's advice in this post viewtopic.php?f=62&t=4534

The UART port is what RobotC uses for dowloading and debugging. This is how the Arduino is wired. Timothy suggested putting in a delay before setting the port speed. When you need to redownload the code hit the Arduino's reset button.

Well, don't I look stupid. I must have glossed over that bit about waiting before setting the baud rate. I knew about ROBOTC uses the same port for downloading, but since the firmware was downloading fine, I thought the user set baud rate wouldn't affect the program download. I'll try using the delay. Thanks.