COrnell Miniature ATmel Operating System (COMATOS)

UART and Debugging Facilities

COMATOS includes some debugging features, which can be made available by passing the DEBUG flag to OSInit. Upon being passed this flag, OSInit initializes the UART to 9600bps.

DinkyBug Utility

Because of the complexities and overhead involved in formatting register dumps and other debugging messages, these tasks are best performed by the PC. The DinkyBug utility translates debugging flags from the MCU into more presentable messages. For example, when the MCU performs a register dump, it sends the flag character 0xfc to the PC, followed by 32 bytes of register values. The register values are formatted neatly and displayed on the screen.

The debugging messages which can be identified by DinkyBug are as follows.

Program Counter Dump: The value of the PC is displayed in hex.

Timeout: When a task fails to return within the time alotted by OSMaxTimeout, a message indicating which task failed, the approximate program counter value, and a register dump are displayed.
Bad Return Code: When a task passes a return code other than 0 to the scheduler, the system halts and causes a message to be displayed, which contains the culprit task and the return code issued.
No Tasks: When the scheduler is run and no tasks have been created using OSCreateTask, the system halts and displays this message.

DinkyBug will also accept any non-debugging data from the MCU. It also allows the user to send characters back to the MCU.

To use DinkyBug, run the executable with a command line argument specifying the I/O address of the serial port. For example, COM2 is usually at address 0x2f8. Thus, one would type:

DinkyBug 2f8