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mVision 2 Debug Program Example

17-39

Keil Simulator

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 µVersion 2 debug program.

Note:

Even though the µVersion 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.

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Texas-instruments MSC1210 Manuale Utente Pagina 267