Re: Re: Help regarding UART
"G.V.Sasanka" <[email protected]>
| Newsgroups | gmane.comp.hardware.motorola.microcontrollers |
|---|---|
| Message-ID | <[email protected]> |
Hi,
I thank you for replying so promptly....I agree with you...and infact i have proceeded the same fashion but i chose TCR1 prescale value as 00 and PSCK as 0 i.e Fsys/32....these happened to be default values in the registers...I got baud rate to be 82hex approximately..hence i was confused and posed it....did u check the application with the answer you got...did it work?
regards,
Sasanka.G.V
shanz9903 <[email protected]> wrote:
AN2371.pdf
2.1.1 void tpu_uart_transmit_init
baud_rate :-
Baud rate is a measure of the number of times per second a signal
in a communications channel varies, or makes a transition between
states (states being frequencies,
voltage levels, or phase angles). One baud is one such change.
Thus, a 300-baud modem's signal
changes state 300 times each second, while a 600- baud modem's
signal changes state 600 times
per second. The baud_rate value is the number of TCR1 counts per
bit time, and is calculated by
the following equation:
TCR1 counts/second
------------------
number of transitions (baud/second)
Therefore baud_rate = TCR1/9600
If TCR1 counts/second is 10000000 for a 40MHz system clock
baud_rate = 10000000/9600 = 1041.667d
baud_rate = 0x411
So I don't know how they get their value of 0x01B2!
TCR1 might be different but I still can't get their answer!
Maybe Freescale could use this sentence as a get-out ...
The baud rate is set to approximately 9600 baud. The actual baud rate
depends on the clock frequency of the MCU, and the prescaler value
chosen.
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