
Enhanced Serial Communications Interface (ESCI) Module
Low-Power Modes
MC68HC908GR60A MC68HC908GR48A MC68HC908GR32A
Data Sheet
MOTOROLA
Enhanced Serial Communications Interface (ESCI) Module
183
Noise flag (NF) — The NF bit is set when the ESCI detects noise on
incoming data or break characters, including start, data, and stop bits. The
noise error interrupt enable bit, NEIE, in SCC3 enables NF to generate ESCI
error CPU interrupt requests.
Framing error (FE) — The FE bit in SCS1 is set when a 0 occurs where the
receiver expects a stop bit. The framing error interrupt enable bit, FEIE, in
SCC3 enables FE to generate ESCI error CPU interrupt requests.
Parity error (PE) — The PE bit in SCS1 is set when the ESCI detects a parity
error in incoming data. The parity error interrupt enable bit, PEIE, in SCC3
enables PE to generate ESCI error CPU interrupt requests.
13.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby
modes.
13.5.1 Wait Mode
The ESCI module remains active in wait mode. Any enabled CPU interrupt request
from the ESCI module can bring the MCU out of wait mode.
If ESCI module functions are not required during wait mode, reduce power
consumption by disabling the module before executing the WAIT instruction.
13.5.2 Stop Mode
The ESCI module is inactive in stop mode. The STOP instruction does not affect
ESCI register states. ESCI module operation resumes after the MCU exits stop
mode.
Because the internal clock is inactive during stop mode, entering stop mode during
an ESCI transmission or reception results in invalid data.
13.6 ESCI During Break Module Interrupts
The BCFE bit in the break flag control register (SBFCR) enables software to clear
To allow software to clear status bits during a break interrupt, write a 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 0 to the BCFE bit. With BCFE
at 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,
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