Datasheet

Serial Communications Interface Module (SCI)
MC68HC812A4 Data Sheet, Rev. 7
168 Freescale Semiconductor
14.6 Register Descriptions and Reset Initialization
This section provides register descriptions and reset initialization.
14.6.1 SCI Baud Rate Registers
Read: Anytime
Write: SBR[12:0] anytime; BTST, BSPL, and BRLD only in special modes
BTST — Reserved for test function
BSPL — Reserved for test function
BRLD — Reserved for test function
SBR[12:0] — SCI Baud Rate Bits
The value written to SBR[12:0] determines the baud rate of the SCI. The new value takes effect when
the low order byte is written. The formula for calculating baud rate is:
BR = value written to SBR[12:0], a value from 1 to 8191
NOTE
The baud rate generator is disabled until the TE bit or the RE bit is set for
the first time after reset. The baud rate generator is disabled when BR = 0.
SCI0: $00C0
SCI1: $00C8
Bit 7654321Bit 0
Read:
BTST BSPL BRLD SBR12 SBR11 SBR10 SBR9 SBR8
Write:
Reset:00000000
Figure 14-17. SCI Baud Rate Register High (SC0BDH or SC1BDH)
SCI0: $00C1
SCI1: $00C9
Bit 7654321Bit 0
Read:
SBR7 SBR6 SBR5 SBR4 SBR3 SBR2 SBR1 SBR0
Write:
Reset:00000100
Figure 14-18. SCI Baud Rate Register Low (SC0BDL or SC1BDL)
SCI baud rate
MCLK
16 BR×
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