MC68HC908MR8 Datasheet, PDF (275/372 Pages) Motorola, Inc – Microcontrollers

Serial Communications Interface (SCI)
I/O Registers
13.9.5 SCI Status Register 2
SCI status register 2 (SCS2) contains flags to signal these conditions:
• Break character detected
• Incoming data
Ad-
dress:
$003C
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
0
0
0
0
0
BKF RPF
Write: R
R
R
R
R
R
R
R
Reset: 0
0
0
0
0
0
0
0
R = Reserved
Figure 13-12. SCI Status Register 2 (SCS2)
BKF — Break Flag Bit
This clearable, read-only bit is set when the SCI detects a break
character on the PTB0/RxD pin. In SCS1, the FE and SCRF bits are
also set. In 9-bit character transmissions, the R8 bit in SCC3 is
cleared. BKF does not generate a CPU interrupt request. Clear BKF
by reading SCS2 with BKF set and then reading the SCDR. Once
cleared, BKF can become set again only after logic 1s again appear
on the PTB0/RxD pin followed by another break character. Reset
clears the BKF bit.
1 = Break character detected
0 = No break character detected
RPF —Reception-in-Progress Flag Bit
This read-only bit is set when the receiver detects a logic 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
MC68HC908MR8 — Rev 4.1
Freescale Semiconductor
Serial Communications Interface (SCI)
Technical Data
275