Typewriter User Manual

7- 26 MC68340 USER’S MANUAL MOTOROLA
7.4.1.6 CLOCK-SELECT REGISTER (CSR). The CSR selects the baud rate clock for the
channel receiver and transmitter. This register can only be written when the serial module
is enabled (i.e., the STP bit in the MCR is cleared).
NOTE
This register should only be written after the external crystal is
stable (XTAL_RDY bit of the ISR is zero).
CSRA, CSRB $711, $719
76543210
RCS3 RCS2 RCS1 RCS0 TCS3 TCS2 TCS1 TCS0
RESET:
00000000
Write Only Supervisor/User
RCS3–RCS0—Receiver Clock Select
These bits select the baud rate clock for the channel receiver from a set of baud rates
listed in Table 7-4. The baud rate set selected depends upon the auxiliary control
register (ACR) bit 7. Set 1 is selected if ACR bit 7 = 0, and set 2 is selected if ACR bit
7 = 1. The receiver clock is always 16 times the baud rate shown in this list, except
when SCLK is used.
Table 7-4. RCSx Control Bits
RCS3 RCS2 RCS1 RCS0 Set 1 Set 2
0 0 0 0 50 75
0 0 0 1 110 110
0 0 1 0 134.5 134.5
0 0 1 1 200 150
0 1 0 0 300 300
0 1 0 1 600 600
0 1 1 0 1200 1200
0 1 1 1 1050 2000
1 0 0 0 2400 2400
1 0 0 1 4800 4800
1 0 1 0 7200 1800
1 0 1 1 9600 9600
1 1 0 0 38.4k 19.2k
1 1 0 1 76.8k 38.4k
1 1 1 0 SCLK/16 SCLK/16
1 1 1 1 SCLK/1 SCLK/1
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
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