Phytec miniMODUL-537, Руководство по оборудованию

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miniMODUL-537
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PHYTEC Meßtechnik GmbH 2001 L-006e_2
6.2 The Baud Generator of SERIAL0
For the serial interface SERIAL0 the internal baud generator can be
selected by setting bit BD. This requires a system-clock cycle of
12 MHz. The baud rates 4800 and 9600 are possible depending on the
bit SMOD.
For other baud rates timer 1 has to be used as baud generator. Then
this timer can not be used anymore during the data transmission for
other purposes.
Timer 1 is used as baud generator, as long as bit BD is not set. For this
version timer 1 must be also initialized and started. For these purposes
the registers TMOD, TCON and TH1 are available. As an example we
refer to the following assembler program. To generate proper baud
rates the system-clock frequency must be appropriate. The standard
frequency of timer 1 is 11.059 MHz.
For deviating frequencies calculations have to be done according to
the computation rules in the controller manual, if the required baud
rates can be generated with the gradation which is necessary for the
reload-register TH1. In the following you find a table with all possible
baud rates for the standard frequency of 12 and 11.059 MHz.
The controller versions with 16 MHz can be operated for SERIAL1 at
9600 and 4800 baud. For SERIAL0 no sufficient accurate adjustment
for this baud rate at 16 MHz is possible.