Z8F0113HJ005EG Datasheet, PDF (90/245 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F0823 Series
Product Specification
75
PWM SINGLE OUTPUT Mode
In PWM SINGLE OUTPUT Mode, the timer outputs a PWM output signal through a
GPIO port pin. The timer input is the system clock. The timer first counts up to the 16-bit
PWM match value stored in the Timer PWM High and Low Byte registers. When the
timer count value matches the PWM value, the Timer Output toggles. The timer continues
counting until it reaches the reload value stored in the Timer Reload High and Low Byte
registers. Upon reaching the reload value, the timer generates an interrupt, the count value
in the Timer High and Low Byte registers is reset to 0001H and counting resumes.
If the TPOL bit in the Timer Control Register is set to 1, the Timer Output signal begins as
a High (1) and transitions to a Low (0) when the timer value matches the PWM value. The
Timer Output signal returns to a High (1) after the timer reaches the reload value and is
reset to 0001H.
If the TPOL bit in the Timer Control Register is set to 0, the Timer Output signal begins as
a Low (0) and transitions to a High (1) when the timer value matches the PWM value. The
Timer Output signal returns to a Low (0) after the timer reaches the reload value and is
reset to 0001H.
Observe the following steps to configure a timer for PWM Single Output mode and initiat-
ing the PWM operation:
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 (typi-
cally 0001H); this write 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:
PS024315-1011
PRELIMINARY
Operation