Datasheet

Serial Communications Interface Module (SCI)
MC68HC812A4 Data Sheet, Rev. 7
174 Freescale Semiconductor
14.6.6 SCI Data Registers
Read: Anytime; reading accesses receive data register
Write: Anytime; writing accesses transmit data register; writing to R8 has no effect
R8 — Received Bit 8
R8 is the ninth data bit received when the SCI is configured for 9-bit data format (M = 1).
T8 — Transmitted Bit 8
T8 is the ninth data bit transmitted when the SCI is configured for 9-bit data format (M = 1).
R7–R0 — Received Bits 7–0
T7–T0 — Transmitted Bits 7–0
NOTE
If the value of T8 is the same as in the previous transmission, T8 does not
have to be rewritten. The same value is transmitted until T8 is rewritten.
In 8-bit data format, only SCI data register low (SCDRL) needs to be
accessed.
When transmitting in 9-bit data format and using 8-bit write instructions,
write first to SCI data register high (SCDRH).
SCI0: $00C6
SCI1: $00CE
Bit 7654321Bit 0
Read: R8
T8
000000
Write:
Reset: Unaffected by reset
= Unimplemented
Figure 14-23. SCI Data Register High (SC0DRH or SC1DRH)
SCI0: $00C7
SCI1: $00CF
Bit 7654321Bit 0
Read:R7R6R5R4R3R2R1R0
Write: T7 T6 T5 T4 T3 T2 T1 T0
Reset: Unaffected by reset
Figure 14-24. SCI Data Register Low (SC0DRL or SC1DRL)