MC68HC08AZ60 Datasheet, PDF (374/452 Pages) Motorola, Inc – Advance Information

Freescale Semiconductor, Inc.
Timer Interface Module A (TIMA-6)
status and control register (TASC3) is unused. While the MS2B bit is set,
the channel 3 pin, PTF1/TACH3, is available as a general-purpose I/O
pin.
Channels 4 and 5 can be linked to form a buffered PWM channel whose
output appears on the PTF2 pin. The TIMA channel registers of the
linked pair alternately control the pulse width of the output.
Setting the MS4B bit in TIMA channel 4 status and control register
(TASC4) links channel 4 and channel 5. The TIMA channel 4 registers
initially control the pulse width on the PTF2 pin. Writing to the TIMA
channel 5 registers enables the TIMA channel 5 registers to
synchronously control the pulse width at the beginning of the next PWM
period. At each subsequent overflow, the TIMA channel registers (4 or
5) that control the pulse width are the ones written to last. TASC4
controls and monitors the buffered PWM function, and TIMA channel 5
status and control register (TASC5) is unused. While the MS4B bit is set,
the channel 5 pin, PTF3, is available as a general-purpose I/O pin.
NOTE:
In buffered PWM signal generation, do not write new pulse width values
to the currently active channel registers. Writing to the active channel
registers is the same as generating unbuffered PWM signals.
PWM Initialization
To ensure correct operation when generating unbuffered or buffered
PWM signals, use the following initialization procedure:
1. In the TIMA status and control register (TASC):
a. Stop the TIMA counter by setting the TIMA stop bit, TSTOP.
b. Reset the TIMA counter by setting the TIMA reset bit, TRST.
2. In the TIMA counter modulo registers (TAMODH–TAMODL), write
the value for the required PWM period.
3. In the TIMA channel x registers (TACHxH–TACHxL), write the
value for the required pulse width.
4. In TIMA channel x status and control register (TSCx):
a. Write 0:1 (for unbuffered output compare or PWM signals) or
1:0 (for buffered output compare or PWM signals) to the mode
select bits, MSxB–MSxA. (See Table 2).
MC68HC08AZ60 — Rev 1.0
374
Timer Interface Module A (TIMA-6)
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