z8f083a ZiLOG Semiconductor, z8f083a Datasheet - Page 80

• Manufacturer Part Number: z8f083a
• Description: High-performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

PS026308-1207
Caution:
2. Write to the timer high and low byte registers to set the starting count value (usually
3. Write to the timer reload high and low byte registers to set the reload value.
4. Enable the timer interrupt (if appropriate) and set the timer interrupt priority by
5. Configure the associated GPIO port pin (if using the timer output function) for the
6. Write to the timer control register to enable the timer and initiate counting.
In CONTINUOUS mode, the system clock always provides the timer input. The timer
period is given by the following equation:
If an initial starting value other than
registers, use the ONE-SHOT mode equation to determine the first time-out period.
COUNTER Mode
In COUNTER mode, the timer counts input transitions from a GPIO port pin. The timer
input is taken from the GPIO port pin: timer input alternate function. The TPOL bit in the
timer control register determines whether the count occurs on the rising edge or the falling
edge of the timer input signal. In COUNTER mode, the prescaler is disabled.
On reaching the reload value stored in the timer reload high and low byte registers, the
timer generates an interrupt, the count value in the timer high and low byte registers is
reset to
enabled, the timer output pin changes state (from low to high or from high to low) at timer
reload.
The steps for configuring a timer for COUNTER mode and for initiating the count are as
follows:
1. Write to the timer control register to:
Continuous Mode Time-Out Period (s)
The input frequency of the timer input signal must not exceed one-fourth the system
clock frequency.
–
0001H). This action only affects the first pass in CONTINUOUS mode. After the first
timer reload in CONTINUOUS mode, counting always begins at the reset value of
0001H
writing to the relevant interrupt registers.
timer output alternate function.
–
–
0001H
If using the timer output alternate function, set the initial output level (high or
low)
Disable the timer
Configure the timer for COUNTER mode
.
and counting resumes. Also, if the timer output alternate function is
0001H
=
is loaded into the timer high and low byte
--------------------------------------------------------------------------- -
System Clock Frequency (Hz)
Reload Value Prescale
Z8 Encore!
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Product Specification
®
F083A Series
Timers
68