mc68hc908as60 Freescale Semiconductor, Inc, mc68hc908as60 Datasheet - Page 241

• Manufacturer Part Number: mc68hc908as60
• Description: Mc68hc908as60 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

17.7 SCI During Break Module Interrupts
17.8 I/O Signals
17.8.1 PTE0/SCTxD (Transmit Data)
MC68HC908AS60 — Rev. 1.0
Because the internal clock is inactive during stop mode, entering stop
mode during an SCI transmission or reception results in invalid data.
The BCFE bit in the break flag control register (BFCR) enables software
to clear status bits during the break state. (See
Module.)
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 2-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.
Port E shares two of its pins with the SCI module. The two SCI I/O pins
are:
The PTE0/SCTxD pin is the serial data output from the SCI transmitter.
The SCI shares the PTE0/SCTxD pin with port E. When the SCI is
enabled, the PTE0/SCTxD pin is an output regardless of the state of the
DDRE2 bit in data direction register E (DDRE).
1. PTE0/SCTxD — Transmit data
2. PTE1/SCRxD — Receive data
Freescale Semiconductor, Inc.
For More Information On This Product,
Serial Communications Interface (SCI)
Go to: www.freescale.com
Serial Communications Interface (SCI)
SCI During Break Module Interrupts
Section 12. Break
Technical Data