Z8F082ASH020SC Datasheet, PDF (82/244 Pages) Zilog, Inc. – Z8 Encore XP-R F08xA Series with eXtended Peripherals

Z8 Encore! XP^® F08xA Series
Product Specification
64
1. Write to the Timer Control register to:
– 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 appropriate, 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 represented 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, use the ONE-SHOT mode equation 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 repre-
sented 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 repre-
sented by:
PWM Output High Time Ratio (%) = --P----W------M-------V----a---l--u---e-- × 100
Reload Value
PWM Dual Output Mode
In PWM DUAL OUTPUT mode, the timer outputs a Pulse-Width Modulated (PWM) out-
put signal pair (basic PWM signal and its complement) through two GPIO Port pins. The
timer input is the system clock. The timer first counts up to the 16-bit PWM match value
PS024705-0405
PRELIMINARY
Timers