MC68HC05X16 Datasheet, PDF (123/232 Pages) Freescale Semiconductor, Inc – High-density complementary metal oxide semiconductor HCMOS) microcontroller unit

Freescale Semiconductor, Inc.
Table 7-9 SCI transmit baud rate output for a given prescaler output
SCT/SCR bits
Bit 2 Bit 1 Bit 0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Divide
by
1
2
4
8
16
32
64
128
Representative highest prescaler baud rate output
131072 32768 38400 19200 9600
131072 32768 38400 19200 9600
65536 16384 19200 9600 4800
32768 8192
9600
4800
2400
16384 4096
4800
2400
1200
8192 2048
2400 1200
600
4096 1024
1200
600
300
2048
512
600
300
150
1024
256
300
150
75
Note:
The examples shown in Table 7-6, Table 7-7, Table 7-8 and Table 7-9 do not apply when
the part is operating in slow mode (see Section 2.2.3).
For the receiver, the internal clock frequency is 16 times higher than the selected baud
rate.
7
7.13
SCI during STOP mode
When the MCU enters STOP mode, the baud rate generator driving the receiver and transmitter
is shut down. This stops all SCI activity. Both the receiver and the transmitter are unable to operate.
If the STOP instruction is executed during a transmitter transfer, that transfer is halted. When STOP
mode is exited as a result of an external interrupt, that particular transmission resumes.
If the receiver is receiving data when the STOP instruction is executed, received data sampling is
stopped (baud generator stops) and the rest of the data is lost.
Warning: For the above reasons, all SCI transactions should be in the idle state when the STOP
instruction is executed.
7.14
SCI during WAIT mode
The SCI system is not affected by WAIT mode and continues normal operation. Any valid SCI
interrupt will wake-up the system. If required, the SCI system can be disabled prior to entering
WAIT mode by writing a zero to the transmitter and receiver enable bits in the serial communication
control register 2 at $000F. This action will result in a reduction of power consumption during WAIT
mode.
MC68HC05X16
SERIAL COMMUNICATIONS INTERFACE
For More Information On This Product,
7-21
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