#106 SSP timing wrong at maximum Baud rate

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nobody
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2010-06-19
2010-06-19
Robert Pearce
No

The MSSP peripheral can be configured to four different Baud rates. The fastest of these is the same as the instruction clock, so for a 40MHz 18F4321 the maximum Baud rate is 10Mb. However, this is implemented as half that rate because the SSP implementation needs to "tick" on both edges of its clock and uses the standard instruction-cycle break mechanism.

For at least one project of mine, this is a pain, because the predictability of SPI in master mode means that cycle-counting is a practical option at this Baud rate, and GPSim then behaves really quite wrongly.

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