Z8 Encore!® Motor Control Flash MCUs
Product Specification
98
The Timer Output signal begins with a value equal to TPOLand then transitions to TPOL
when the timer value matches the PWM value. The Timer Output signal returns to TPOL
after the timer reaches the reload value, and is reset to 0001h.
In PWM DUAL OUTPUT mode, the timer also generates a second PWM output signal,
Timer Output Complement (TOUT). A programmable deadband can be configured (PWMD
field) to delay (0–128 system clock cycles) the Low to a High (inactive to active) output
transitions on these two pins. This configuration ensures a time gap between the deasser-
tion of one PWM output to the assertion of its complement.
The steps for configuring a timer for either PWM SINGLE or DUAL OUTPUT mode and
initiating PWM operation are as follows:
1. Write to the Timer Control registers to:
a. Disable the timer.
b. Configure the timer for the selected PWM mode.
c. Set the prescale value.
d. Set the initial logic level (High or Low) and PWM High/Low transition for the
Timer Output alternate function with the TPOLbit.
e. Set the deadband delay (DUAL OUTPUT mode) with the PWMDfield.
2. Write to the Timer High and Low Byte registers to set the starting count value (typi-
cally 0001h). The starting count value only affects the first pass in PWM mode. After
the first timer reset in PWM mode, counting 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(s) for the Timer Output alternate function.
7. Write to the Timer Control 1 Register to enable the timer and initiate counting.
The PWM period is determined by the following equation:
Reload Value x Prescaler
PWM Period(s) =
System Clock Frequency (Hz)
If an initial starting value other than 0001his loaded into the Timer High and Low Byte
registers, use the ONE-SHOT mode equation to determine the first PWM time-out period.
General-Purpose Timer
P R E L I M I N A R Y
PS024604-1005
ZILOG [ ZILOG, INC. ]
