AT91SAM7S DBGU serial port

Jun 07, 2006 3 Replies

I am looking at an application where I bring to the outside world a single serial port. I would like to use this same port for uploading of new code. On the SAM7 processors this can be done using the DBGU port. But I am not sure if using this port in the application code will be fully compatible with all the debugging features.



In addition to the SAM-BA boot code loader, the documentation shows the DBGU having the functions of "Debug Monitor" and "Trace Manager". I am not familiar with these and have not found any real description of these functions in the data sheet. It also shows COMMRX and COMMTX signals from the ARM processor that are used with the "Debug Communication Channel". I am not familiar with any of these debug features and can't tell if using the DBGU serial port in the application will prevent their usage in debugging.



Has anyone used any of these debugging features or know how they are used? Can I assume that if we use the JTAG debugger, we don't need any of these other debug features?



I am using the DBGU port as a normal UART (take note that it does not support 9 bits protocol) and I do my debugging with the JTAG interface (Crosswork for AMR). Everything is working really fine.

The DBGU is used by internal Boot ROMs for various uses. It also has a connection to the JTAG. I am not aware that this function is used anywhere, but I might be wrong...

For all practical use You can use the DBGU as a serial port in your application. It is a little more limited in functionality compared the the std USART though.

Best Regards, Ulf Samuelsson ulf@a-t-m-e-l.com This message is intended to be my own personal view and it may or may not be shared by my employer Atmel Nordic AB

I think the old Angel Debug Monitor could use DBGU to support debugging over the serial port?

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