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CMS80F731x Reference Manual
22.6.3
Mode 2-9 Bit Asynchronous Mode (Fixed Baud Rate)
This mode is similar to Mode 1, but differs in two ways. The baud rate is fixed at 1/32 or 1/64 of the CLK clock frequency,
with 11 bits of transceiver: start bit (0), 8 bits of data (LSB first), programmable bit 9, and stop bit (1). Bit 9 can be used to control
parity of the UARTn interface: at send time, bit TBn8 in SCONn acts as the 9th bit output, and on receive, bit 9 affects RBn8 in
SCONn. The Mode 3 timing diagram is shown in the following figure:
D1
D2
D3
D4
D5
D6
TXDn
TIn
RXDn
TB8
D0
STOP
START
D7
22.6.4
Mode 3-9 Bit Asynchronous Mode (Variable Baud Rate)
The only difference between mode 2 and mode 3 is that the baud rate in mode 3 is variable. When REN0=1, data reception
is enabled. The baud rate is variable and depends on the TIMER1/TIMER2/TIMER4/BRT mode. The Mode 4 timing diagram is
shown in the following figure:
D1
D2
D3
D4
D5
D6
TXDn
TIn
RXDn
TB8
D0
STOP
START
D7