Datasheet

Serial Interface
M68HC12B Family Data Sheet, Rev. 9.1
200 Freescale Semiconductor
14.2.3.6 SCI Data Register
Read: Anytime
Write: Varies on a bit by bit basis
R8 — Receive Bit 8
Write has no meaning or effect.
This bit is the ninth serial data bit received when the SCI system is configured for 9-data-bit operation.
T8 — Transmit Bit 8
Write anytime.
This bit is the ninth serial data bit transmitted when the SCI system is configured for 9-data-bit
operation. When using 9-bit data format, this bit does not have to be written for each data word. The
same value is transmitted as the ninth bit until this bit is rewritten.
R7T7–R0T0 — Receive/Transmit Data Bits 7 to 0
Reads access the eight bits of the read-only SCI receive data register (RDR). Writes access the eight
bits of the write-only SCI transmit data register (TDR). SC0DRL and SC0DRH form the 9-bit data word
for the SCI. If the SCI is being used with a 7- or 8-bit data word, only SC0DRL needs to be accessed.
If a 9-bit format is used, the upper register should be written first to ensure that it is transferred to the
transmitter shift register with the lower register.
Address: $00C6
Bit 7654321Bit 0
Read: R8
T8
000000
Write:
Reset:UU000000
= Unimplemented U = Unaffected
Figure 14-9. SCI Data Register High (SC0DRH)
Address: $00C7
Bit 7654321Bit 0
Read:
R7T7 R6T6 R5T5 R4T4 R3T3 R2T2 R1T1 R0T0
Write:
Reset: Unaffected by reset
Figure 14-10. SCI Data Register Low (SC0DRL)