Z8F6421PM020SC Datasheet, PDF (99/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
79
– Select either the rising edge or falling edge of the Timer Input signal for the count.
This also sets the initial logic level (High or Low) for the Timer Output alternate
function. However, the Timer Output function does not have to be enabled
2. Write to the Timer High and Low Byte registers to set the starting count value. This
only affects the first pass in COUNTER mode. After the first timer Reload in
COUNTER mode, counting always begins at the reset value of 0001H. Generally, in
COUNTER mode the Timer High and Low Byte registers must be written with the
value 0001H.
3. Write to the Timer Reload High and Low Byte registers to set the Reload value.
4. If desired, enable the timer interrupt and set the timer interrupt priority by writing to
the relevant interrupt registers.
5. Configure the associated GPIO port pin for the Timer Input alternate function.
6. If using the Timer Output function, configure the associated GPIO port pin for the
Timer Output alternate function.
7. Write to the Timer Control 1 register to enable the timer.
In COUNTER mode, the number of Timer Input transitions since the timer start is given
by the following equation:
Counter Mode Timer Input Transitions = Current Count Value ∠ Start Value
PWM Mode
In PWM mode, the timer outputs a Pulse-Width Modulator (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 1 register is set to 1, the Timer Output signal begins
as a High (1) and then 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 1 register is set to 0, the Timer Output signal begins
as a Low (0) and then 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.
The steps for configuring a timer for PWM mode and initiating the PWM operation are as
follows:
PS019915-1005
Timers