MC68HC08AZ60A Datasheet, PDF (293/480 Pages) Motorola, Inc – Microcontrollers

Timer Interface Module B (TIMB)
TIMB During Break Interrupts
18.7 TIMB During Break Interrupts
A break interrupt stops the TIMB counter and inhibits input captures.
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state (see SIM Break Flag Control Register
(SBFCR) on page 137).
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.
18.8 I/O Signals
Port D shares one of its pins with the TIMB. Port F shares two of its pins
with the TIMB. PTD4/ATD12/TBCLK is an external clock input to the
TIMB prescaler. The two TIMB channel I/O pins are PTF4/TBCH0 and
PTF5/TBCH1.
18.8.1 TIMB Clock Pin (PTD4/ATD12/TBCLK)
PTD4/ATD12/TBCLK is an external clock input that can be the clock
source for the TIMB counter instead of the prescaled internal bus clock.
Select the PTD4/ATD12/TBCLK input by writing logic 1s to the three
prescaler select bits, PS[2:0] (see TIMB Status and Control Register).
The minimum TCLK pulse width, TCLK_LMIN or TCLK_HMIN, is:
b----u---s-----f--r--e--1-q---u----e---n---c---y-- ^{+ tSU}
MC68HC08AZ60A — Rev 0.0
MOTOROLA
Timer Interface Module B (TIMB)
Advance Information
293