Z8 Encore! XP® 4K Series
Product Specification
70
duration of the negative phase of the PWM signal (as defined by the difference
between the PWM registers and the Timer Reload registers).
5. 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.
6. If appropriate, enable the timer interrupt and set the timer interrupt priority by writing
to the relevant interrupt registers.
7. Configure the associated GPIO port pin for the Timer Output and Timer Output
Complement alternate functions. The Timer Output Complement function is shared
with the Timer Input function for both timers. Setting the timer mode to Dual PWM
automatically switches the function from Timer In to Timer Out Complement.
8. Write to the Timer Control register to enable the timer and initiate counting.
The PWM period is represented by the following equation:
Reload Value × Prescale
PWM Period (s) = ---------------------------------------------------------------------------
System Clock Frequency (Hz)
If an initial starting value other than 0001His loaded into the Timer High and Low Byte
registers, the ONE-SHOT mode equation determines the first PWM time-out period.
If TPOLis set to 0, the ratio of the PWM output High time to the total period is repre-
sented by:
Reload Value – PWM Value
-----------------------------------------------------------------------
PWM Output High Time Ratio (%) =
× 100
Reload Value
If TPOLis set to 1, the ratio of the PWM output High time to the total period is repre-
sented by:
PWM Value
Reload Value
---------------------------------
PWM Output High Time Ratio (%) =
× 100
CAPTURE Mode
In CAPTURE mode, the current timer count value is recorded when the appropriate exter-
nal 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 Timer Input signal. When the Capture event occurs, an interrupt is generated and the
timer continues counting. The INPCAP bit in TxCTL0 register is set to indicate the timer
interrupt is because of an input capture event.
The timer continues counting up to the 16-bit Reload value stored in the Timer Reload
High and Low Byte registers. Upon reaching the Reload value, the timer generates an
PS022815-0206
Timers
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