
Serial Communication Interface (S08SCIV4)
MM912_634 Advance Information, Rev. 10.0
Freescale Semiconductor
111
5.16.2.5
SCI Status Register 2 (SCIS2)
This register has one read-only status flag.
4
IDLE
Idle Line Flag — IDLE is set when the SCI receive line becomes idle for a full character time after a period of activity. When
ILT = 0, the receiver starts counting idle bit times after the start bit. So if the receive character is all 1s, these bit times and the
stop bit time count toward the full character time of logic high (10 or 11 bit times depending on the M control bit) needed for the
receiver to detect an idle line. When ILT = 1, the receiver doesn’t start counting idle bit times until after the stop bit. So the stop
bit and any logic high bit times at the end of the previous character do not count toward the full character time of logic high
needed for the receiver to detect an idle line.
To clear IDLE, read SCIS1 with IDLE = 1 and then read the SCI data register (SCID). After IDLE has been cleared, it cannot
become set again until after a new character has been received and RDRF has been set. IDLE will get set only once even if
the receive line remains idle for an extended period.
0
No idle line detected.
1
Idle line was detected.
3
OR
Receiver Overrun Flag — OR is set when a new serial character is ready to be transferred to the receive data register (buffer),
but the previously received character has not been read from SCID yet. In this case, the new character (and all associated
error information) is lost because there is no room to move it into SCID. To clear OR, read SCIS1 with OR = 1 and then read
the SCI data register (SCID).
0
No overrun.
1
Receive overrun (new SCI data lost).
2
NF
Noise Flag — The advanced sampling technique used in the receiver takes seven samples during the start bit and three
samples in each data bit and the stop bit. If any of these samples disagrees with the rest of the samples within any bit time in
the frame, the flag NF will be set at the same time as the flag RDRF gets set for the character. To clear NF, read SCIS1 and
then read the SCI data register (SCID).
0
No noise detected.
1
Noise detected in the received character in SCID.
1
FE
Framing Error Flag — FE is set at the same time as RDRF when the receiver detects a logic 0 where the stop bit was expected.
This suggests the receiver was not properly aligned to a character frame. To clear FE, read SCIS1 with FE = 1 and then read
the SCI data register (SCID).
0
No framing error detected. This does not guarantee the framing is correct.
1
Framing error.
0
PF
Parity Error Flag — PF is set at the same time as RDRF when parity is enabled (PE = 1) and the parity bit in the received
character does not agree with the expected parity value. To clear PF, read SCIS1 and then read the SCI data register (SCID).
0
No parity error.
1
Parity error.
Table 144. SCI Status Register 2 (SCIS2)
0x45
Access: User read/write
7
654
32
10
R
0
RAF
W
Reset
0
000
00
Note:
104. Offset related to 0x0200 for blocking access and 0x300 for non blocking access within the global address space.
Table 143. SCIS1 Field Descriptions (continued)
Field
Description