XC886/888CLM
Serial Interfaces
User’s Manual
12-22
V1.3, 2010-02
Serial Interfaces, V 1.0
12.1.4.3
Timer 1
In modes 1 and 3 of UART module, Timer 1 can be used for generating the variable baud
rates. In theory, this timer could be used in any of its modes. But in practice, it should be
set into auto-reload mode (Timer 1 mode 2), with its high byte set to the appropriate
value for the required baud rate. The baud rate is determined by the Timer 1 overflow
rate and the value of SMOD as follows:
(12.6)
Alternatively, for a given baud rate, the value of Timer 1 high byte can be derived:
(12.7)
Note: Timer 1 can neither indicate an overflow nor generate an interrupt if Timer 0 is in
mode 3; Timer 1 is halted while Timer 0 takes over the use of its control bits and
overflow flag. Hence, the baud rate supplied to the UART module is defined by
Timer 0 and not Timer 1. User should avoid using Timer 0 and Timer 1 in mode 3
for baud rate generation.
Note: Timer 1 cannot be used to generate the variable baud rate in UART1.
TH1)
-
(256
x
2
x
32
PCLK
f
x
SMOD
2
rate
baud
3
,
1
Mode
=
rate
baud
3
,
1
Mode
x
2
x
32
PCLK
f
x
SMOD
2
256
TH1
−
=
*