MC908AP16CFAE Datasheet, PDF (203/324 Pages) Freescale Semiconductor, Inc – Table of Contents

I/O Registers
12.9.4 IRSCI Status Register 1
SCI status register 1 contains flags to signal these conditions:
• Transfer of IRSCDR data to transmit shift register complete
• Transmission complete
• Transfer of receive shift register data to IRSCDR complete
• Receiver input idle
• Receiver overrun
• Noisy data
• Framing error
• Parity error
Address: $0043
Bit 7
6
5
4
3
2
1
Bit 0
Read: SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
Write:
Reset: 1
1
0
0
0
0
0
0
= Unimplemented
Figure 12-15. IRSCI Status Register 1 (IRSCS1)
SCTE — SCI Transmitter Empty Bit
This clearable, read-only bit is set when the IRSCDR transfers a character to the transmit shift register.
SCTE can generate an SCI transmitter CPU interrupt request. When the SCTIE bit in IRSCC2 is set,
SCTE generates an SCI transmitter CPU interrupt request. In normal operation, clear the SCTE bit by
reading IRSCS1 with SCTE set and then writing to IRSCDR. Reset sets the SCTE bit.
1 = IRSCDR data transferred to transmit shift register
0 = IRSCDR data not transferred to transmit shift register
TC — Transmission Complete Bit
This read-only bit is set when the SCTE bit is set, and no data, preamble, or break character is being
transmitted. TC generates an SCI transmitter CPU interrupt request if the TCIE bit in IRSCC2 is also
set. TC is automatically cleared when data, preamble or break is queued and ready to be sent. There
may be up to 1.5 transmitter clocks of latency between queueing data, preamble, and break and the
transmission actually starting. Reset sets the TC bit.
1 = No transmission in progress
0 = Transmission in progress
SCRF — SCI Receiver Full Bit
This clearable, read-only bit is set when the data in the receive shift register transfers to the SCI data
register. SCRF can generate an SCI receiver CPU interrupt request. When the SCRIE bit in IRSCC2
is set, SCRF generates a CPU interrupt request. In normal operation, clear the SCRF bit by reading
IRSCS1 with SCRF set and then reading the IRSCDR. Reset clears SCRF.
1 = Received data available in IRSCDR
0 = Data not available in IRSCDR
IDLE — Receiver Idle Bit
This clearable, read-only bit is set when 10 or 11 consecutive logic 1s appear on the receiver input.
IDLE generates an SCI receiver CPU interrupt request if the ILIE bit in IRSCC2 is also set. Clear the
IDLE bit by reading IRSCS1 with IDLE set and then reading the IRSCDR. After the receiver is enabled,
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
203