Z8F1601 Datasheet, PDF (80/246 Pages) Zilog, Inc. – Z8 Encore Microcontrollers with Flash Memory and 10-Bit A/D Converter

Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
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– Disable the timer
– Configure the timer for PWM mode.
– Set the prescale value.
– Set the initial logic level (High or Low) and PWM High/Low transition for the
Timer Output alternate function.
2. Write to the Timer High and Low Byte registers to set the starting count value
(typically 0001H). This only affects the first pass in PWM mode. After the first timer
reset in PWM mode, counting always begins at the reset value of 0001H.
3. Write to the PWM High and Low Byte registers to set the PWM value.
4. Write to the Timer Reload High and Low Byte registers to set the Reload value (PWM
period). The Reload value must be greater than the PWM value.
5. If desired, enable the timer interrupt and set the timer interrupt priority by writing to
the relevant interrupt registers.
6. Configure the associated GPIO port pin for the Timer Output alternate function.
7. Write to the Timer Control register to enable the timer and initiate counting.
The PWM period is given by the following equation:
PWM Period (s) = --------R----e---l-o---a---d-----V-----a---l-u----e----^×-----P---r---e---s--c---a---l-e--------
System Clock Frequency (Hz)
If an initial starting value other than 0001H is loaded into the Timer High and Low Byte
registers, the One-Shot mode equation must be used to determine the first PWM time-out
period.
If TPOL is set to 0, the ratio of the PWM output High time to the total period is given by:
PWM Output High Time Ratio (%) = -R----e---l-o---a---d-----V----a---l--u---e-----^–----P----W------M-------V----a---l--u---e- × 100
Reload Value
If TPOL is set to 1, the ratio of the PWM output High time to the total period is given by:
PWM Output High Time Ratio (%)
=
--P---W------M--------V----a---l--u---e--
Reload Value
×
100
Capture Mode
In Capture mode, the current timer count value is recorded when the desired external
Timer Input transition occurs. The Capture count value is written to the Timer PWM High
and Low Byte Registers. The timer input is the system clock. The TPOL bit in the Timer
Control register determines if the Capture occurs on a rising edge or a falling edge of the
PS017610-0404
Timers