MC68HC08AZ60A Datasheet, PDF (287/480 Pages) Motorola, Inc – Microcontrollers

Timer Interface Module B (TIMB)
Functional Description
• When changing to a smaller value, enable channel x output
compare interrupts and write the new value in the output compare
interrupt routine. The output compare interrupt occurs at the end
of the current output compare pulse. The interrupt routine has until
the end of the counter overflow period to write the new value.
• When changing to a larger output compare value, enable TIMB
overflow interrupts and write the new value in the TIMB overflow
interrupt routine. The TIMB overflow interrupt occurs at the end of
the current counter overflow period. Writing a larger value in an
output compare interrupt routine (at the end of the current pulse)
could cause two output compares to occur in the same counter
overflow period.
18.4.3.2 Buffered Output Compare
Channels 0 and 1 can be linked to form a buffered output compare
channel whose output appears on the PTF4/TBCH0 pin. The TIMB
channel registers of the linked pair alternately control the output.
Setting the MS0B bit in TIMB channel 0 status and control register
(TBSC0) links channel 0 and channel 1. The output compare value in the
TIMB channel 0 registers initially controls the output on the
PTF4/TBCH0 pin. Writing to the TIMB channel 1 registers enables the
TIMB channel 1 registers to synchronously control the output after the
TIMB overflows. At each subsequent overflow, the TIMB channel
registers (0 or 1) that control the output are the ones written to last.
TBSC0 controls and monitors the buffered output compare function and
TIMB channel 1 status and control register (TBSC1) is unused. While the
MS0B bit is set, the channel 1 pin, PTF5/TBCH1, is available as a
general-purpose I/O pin.
NOTE:
In buffered output compare operation, do not write new output compare
values to the currently active channel registers. User software should
track the currently active channel to prevent writing a new value to the
active channel. Writing to the active channel registers is the same as
generating unbuffered output compares.
MC68HC08AZ60A — Rev 0.0
MOTOROLA
Timer Interface Module B (TIMB)
Advance Information
287