
Infrared Serial Communications Interface (IrSCI)
MC68HC08LK60 MC68HC908LK60 Advance Information Data Sheet, Rev. 1.1
134
Freescale Semiconductor
Parity error (PE) — The PE bit in SCS1 is set when the SCI detects a parity error in incoming data.
The parity error interrupt enable bit, PEIE, in SCC3 enables PE to generate SCI error CPU interrupt
requests.
12.6 Wait Mode
The SCI module remains active after the execution of a WAIT instruction. In wait mode the SCI module
registers are not accessible by the CPU. Any enabled CPU interrupt request from the SCI module can
bring the MCU out of wait mode.
If SCI module functions are not required during wait mode, reduce power consumption by disabling the
module before executing the WAIT instruction.
12.7 SCI During Break Module Interrupts
The system integration module (SIM) controls whether status bits in other modules can be cleared during
interrupts generated by the break module. The BCFE bit in the SIM break flag control register (SBFCR)
enables software to clear status bits during the break state.
To allow software to clear status bits during a break interrupt, write a logic 1 to the BCFE bit. If a status
bit is cleared during the break state, it remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a logic 0 to the BCFE bit. With BCFE at logic 0 (its
default state), software can read and write I/O registers during the break state without affecting status bits.
Some status bits have a two-step read/write clearing procedure. If software does the first step on such a
bit before the break, the bit cannot change during the break state as long as BCFE is at logic 0. After the
break, doing the second step clears the status bit.
12.8 I/O Signals
The two IrSCI input/output (I/O) pins are:
TxD — Transmit data
RxD — Receive data
12.8.1 TxD (Transmit Data)
This pin transmits SCI (standard or infrared) data. It will idle high in either mode and is high impedance
anytime the transmitter is disabled.
12.8.2 RxD (Receive Data)
This pin receives SCI (standard or infrared) data. An idle line is detected as a line high. This input is
ignored when the receiver is disabled and should be terminated to a known voltage.
A summary of the I/O pin considerations is given in
Table 12-4.