XC908AS60ACFU Motorola Semiconductor Products, XC908AS60ACFU Datasheet - Page 278

• Manufacturer Part Number: XC908AS60ACFU
• Description: MC68HC908AZ60A, MC68HC908AS60A Hcmos Microcontroller Unit Technical Data
• Manufacturer: Motorola Semiconductor Products

Serial Communications Interface (SCI)
18.9.5 SCI Status Register 2
Technical Data
278
Address:
SCI status register 2 contains flags to signal the following conditions:
BKF — Break Flag Bit
RPF — Reception in Progress Flag Bit
Reset:
Read:
Write:
•
•
This clearable, read-only bit is set when the SCI detects a break
character on the 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 RxD pin followed by another break character. Reset clears the
BKF 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 = Break character detected
0 = No break character detected
1 = Reception in progress
0 = No reception in progress
Break character detected
Incoming data
Serial Communications Interface (SCI)
$0017
Bit 7
0
0
Figure 18-16. SCI Status Register 2 (SCS2)
= Unimplemented
6
0
0
5
0
0
4
0
0
3
0
0
MC68HC908AZ60A — Rev 2.0
2
0
0
BKF
1
0
MOTOROLA
Bit 0
RPF
0