Freescale Semiconductor MC68HC908MR32 - Manual (Page 174)

Serial Communications Interface Module (SCI)
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
174 Freescale Semiconductor
13.7.4 SCI Status Register 1
SCI status register 1 (SCS1) contains flags to signal these conditions:
• Transfer of SCDR data to transmit shift register complete
• Transmission complete
• Transfer of receive shift register data to SCDR complete
• Receiver input idle
• Receiver overrun
• Noisy data
• Framing error
• Parity error
SCTE — SCI Transmitter Empty Bit
This clearable, read-only bit is set when the SCDR transfers a character to the transmit shift register.
SCTE can generate an SCI transmitter CPU interrupt request. When the SCTIE bit in SCC2 is set,
SCTE generates an SCI transmitter CPU interrupt request. In normal operation, clear the SCTE bit by
reading SCS1 with SCTE set and then writing to SCDR. Reset sets the SCTE bit.
1 = SCDR data transferred to transmit shift register
0 = SCDR 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 SCC2 is also set.
TC is cleared automatically 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 SCC2 is
set, SCRF generates a CPU interrupt request. In normal operation, clear the SCRF bit by reading
SCS1 with SCRF set and then reading the SCDR. Reset clears SCRF.
1 = Received data available in SCDR
0 = Data not available in SCDR
Address: $003B
Bit 7 6 5 4 3 2 1 Bit 0
Read: SCTE TC SCRF IDLE OR NF FE PE
Write: R R R R R R R R
Reset: 1 1 0 0 0 0 0 0
R = Reserved
Figure 13-11. SCI Status Register 1 (SCS1)