MC68HC11E0CFNE3 Datasheet, PDF (112/242 Pages) Freescale Semiconductor, Inc – M68HC11E Family

Serial Communications Interface (SCI)
7.7.4 Serial Communication Status Register
The SCSR provides inputs to the interrupt logic circuits for generation of the SCI system interrupt.
Address: $102E
Bit 7
6
5
4
3
2
1
Bit 0
Read:
TDRE
TC
RDRF
IDLE
OR
NF
FE
Write:
Reset: 1
1
0
0
0
0
0
0
= Unimplemented
Figure 7-6. Serial Communications Status Register (SCSR)
TDRE — Transmit Data Register Empty Flag
This flag is set when SCDR is empty. Clear the TDRE flag by reading SCSR with TDRE set and then
writing to SCDR.
0 = SCDR busy
0 = SCDR empty
TC — Transmit Complete Flag
This flag is set when the transmitter is idle (no data, preamble, or break transmission in progress).
Clear the TC flag by reading SCSR with TC set and then writing to SCDR.
0 = Transmitter busy
1 = Transmitter idle
RDRF — Receive Data Register Full Flag
This flag is set if a received character is ready to be read from SCDR. Clear the RDRF flag by reading
SCSR with RDRF set and then reading SCDR.
0 = SCDR empty
1 = SCDR full
IDLE — Idle Line Detected Flag
This flag is set if the RxD line is idle. Once cleared, IDLE is not set again until the RxD line has been
active and becomes idle again. The IDLE flag is inhibited when RWU = 1. Clear IDLE by reading SCSR
with IDLE set and then reading SCDR.
0 = RxD line active
1 = RxD line idle
OR — Overrun Error Flag
OR is set if a new character is received before a previously received character is read from SCDR.
Clear the OR flag by reading SCSR with OR set and then reading SCDR.
0 = No overrun
1 = Overrun detected
NF — Noise Error Flag
NF is set if majority sample logic detects anything other than a unanimous decision. Clear NF by
reading SCSR with NF set and then reading SCDR.
0 = Unanimous decision
1 = Noise detected
M68HC11E Family Data Sheet, Rev. 5.1
112
Freescale Semiconductor