Z8F042AHJ020SG Datasheet, PDF (98/282 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F082A Series
Product Specification
81
3. Write to the Timer Reload High and Low Byte registers to set the reload value.
4. Clear the Timer PWM High and Low Byte registers to 0000H. This allows the soft-
ware to determine if interrupts were generated by either a capture event or a reload. If
the PWM High and Low Byte registers still contain 0000H after the interrupt, the
interrupt was generated by a Reload.
5. Enable the timer interrupt, if appropriate and set the timer interrupt priority by writing
to the relevant interrupt registers. By default, the timer interrupt is generated for both
input capture and reload events. If appropriate, configure the timer interrupt to be gen-
erated only at the input capture event or the reload event by setting TICONFIG field
of the TxCTL0 Register.
6. Configure the associated GPIO port pin for the Timer Input alternate function.
7. Write to the Timer Control Register to enable the timer and initiate counting.
In CAPTURE Mode, the elapsed time from timer start to Capture event can be calculated
using the following equation:
Capture Elapsed Time (s) = ^---^C----^a---^p---^t--^u---^r-^e-----^V----^a---^l-^u---^e----^–-----^S----^t-^a---^r--^t---^V----^a---^l-^u---^e---^----^----^P---^r--^e---^s---^c---^a---^l-^e-
System Clock Frequency (Hz)
COMPARE Mode
In COMPARE Mode, the timer counts up to the 16-bit maximum Compare value stored in
the Timer Reload High and Low Byte registers. The timer input is the system clock. Upon
reaching the Compare value, the timer generates an interrupt and counting continues (the
timer value is not reset to 0001H). Also, if the Timer Output alternate function is enabled,
the Timer Output pin changes state (from Low to High or from High to Low) upon 
Compare.
If the Timer reaches FFFFH, the timer rolls over to 0000H and continue counting.
Observe the following steps for configuring a timer for COMPARE Mode and initiating
the count:
1. Write to the Timer Control Register to:
– Disable the timer
– Configure the timer for COMPARE Mode
– Set the prescale value
PS022827-1212
PRELIMINARY
Operation