MC68HC11D0MFS1 查看數據表（PDF） - Freescale Semiconductor
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MC68HC11D0MFS1 Datasheet PDF : 124 Pages
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Freescale Semiconductor, Inc.
NF — Noise Error Flag
NF is set if majority sample logic detects anything other than a unanimous decision.
Clear NF by reading SCSR with NF set and then reading SCDR.
0 = Unanimous decision
1 = Noise detected
FE — Framing Error
FE is set when a 0 is detected where a stop bit was expected. Clear the FE flag by
reading SCSR with FE set and then reading SCDR.
0 = Stop bit detected
1 = 0 detected
7.6.5 Baud Rate Register (BAUD)
Use this register to select different baud rates for the SCI system. The SCP[1:0] bits
function as a prescaler for the SCR[2:0] bits. Together, these five bits provide multiple
baud rate combinations for a given crystal frequency. Normally, this register is written
once during initialization. The prescaler is set to its fastest rate by default out of reset,
and can be changed at any time. Refer to Table 7-1 and Table 7-2 for normal baud
rate selections.
BAUD — Baud Rate
Bit 7
6
TCLR
0
RESET:
0
0
5
SCP1
0
4
SCP0
0
3
RCKB
0
2
SCR2
U
1
SCR1
U
$002B
Bit 0
SCR0
U
TCLR — Clear Baud Rate Counters (Test)
RCKB — SCI Baud Rate Clock Check (Test)
SCP1, SCP0 — SCI Baud Rate Prescaler Selects
These two bits select a prescale factor for the SCI baud rate generator that determines
the highest possible baud rate.
Table 7-1 Baud Rate Prescale Selects
SCP[1:0]
00
01
10
11
Divide
Internal Clock
By
1
3
4
13
Crystal Frequency in MHz
4.0 MHz 8.0 MHz 10.0 MHz 12.0 MHz
(Baud) (Baud) (Baud) (Baud)
62.50 K 125.0 K 156.25 K 187.5 K
20.83 K 41.67 K 52.08 K 62.5 K
15.625 K 31.25 K 38.4 K 46.88 K
4800
9600 12.02 K 14.42 K
SCR[2:0] — SCI Baud Rate Selects
These three bits select receiver and transmitter bit rate based on output from baud rate
prescaler stage.
SERIAL COMMUNICATIONS INTERFACE
7-8
TECHNICAL DATA
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