mVision 2 Debug Program Example

Figure 17−17. Keil Debugger

The window labeled Serial #1 shows the printed ASCII character representation of the data bytes received by the main SPI program from the debugging pro- gram. Note that the first character printer is an ! mark which has a numerical val- ue of 0x21. This was the first value of j to be transmitted from the debugger through the SPI_IN portal. The subsequent characters are supposed to corre- spond to ASCII characters whose numerical values are a value of one off from the previous character. However, once in a while, there is a skip in characters. This can be explained by the fact that once in a while, the two programs become unsynchronized. Better twatch delay timing would have resolved this issue, but that is not the essence of this example. The Serial #1 window shows the results of two 50-byte transfers from the Version 2 debug program.

Note:

Even though the Version 2 debug program and the main SPI program are separate and independent programs, they run in parallel, and they are syn- chronized. This way, the incoming data from the debugger is always ready when the main SPI program is ready to receive data. The delay timing com- putation is very delicate. If it is too short, data to be transmitted from the de- bugging program will be overwritten before it is transmitted. If it is too long, the data transmitted from the main SPI program will be overwritten before the debugging program reads it.

Keil Simulator

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Texas Instruments MSC1210 manual 17. Keil Debugger