MC68HC908GR8 Datasheet, PDF (183/286 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

I/O Registers
RPF — Reception in Progress Flag Bit
This read-only bit is set when the receiver detects a 0 during the RT1 time period of the start bit search.
RPF does not generate an interrupt request. RPF is reset after the receiver detects false start bits
(usually from noise or a baud rate mismatch) or when the receiver detects an idle character. Polling
RPF before disabling the SCI module or entering stop mode can show whether a reception is in
progress.
1 = Reception in progress
0 = No reception in progress
18.8.6 SCI Data Register
The SCI data register (SCDR) is the buffer between the internal data bus and the receive and transmit
shift registers. Reset has no effect on data in the SCI data register.
Address: $0018
Bit 7
6
Read: R7
R6
Write: T7
T6
Reset:
5
4
3
2
R5
R4
R3
R2
T5
T4
T3
T2
Unaffected by reset
1
Bit 0
R1
R0
T1
T0
Figure 18-15. SCI Data Register (SCDR)
R7/T7–R0/T0 — Receive/Transmit Data Bits
Reading address $0018 accesses the read-only received data bits, R7:R0. Writing to address $0018
writes the data to be transmitted, T7:T0. Reset has no effect on the SCI data register.
NOTE
Do not use read/modify/write instructions on the SCI data register.
18.8.7 SCI Baud Rate Register
The baud rate register (SCBR) selects the baud rate for both the receiver and the transmitter.
Address:
Read:
Write:
Reset:
$0019
Bit 7
6
5
4
3
2
1
0
0
SCP1
SCP0
R
SCR2
SCR1
0
0
0
0
0
0
0
= Unimplemented
R = Reserved
Figure 18-16. SCI Baud Rate Register (SCBR)
Bit 0
SCR0
0
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
Freescale Semiconductor
183