Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
Z8 Encore!®
59
out, first set the TPOLbit in the Timer Control Register to the start value before beginning
One-Shot mode. Then, after starting the timer, set TPOLto the opposite bit value.
The steps for configuring a timer for One-Shot mode and initiating the count are as fol-
lows:
1. Write to the Timer Control register to:
–
–
–
–
Disable the timer
Configure the timer for One-Shot mode.
Set the prescale value.
If using the Timer Output alternate function, set the initial output level (High or
Low).
2. Write to the Timer High and Low Byte registers to set the starting count value.
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. If using the Timer Output function, configure the associated GPIO port pin for the
Timer Output alternate function.
6. Write to the Timer Control register to enable the timer and initiate counting.
In One-Shot mode, the system clock always provides the timer input. The timer period is
given by the following equation:
(Reload Value – Start Value) × Prescale
One-Shot Mode Time-Out Period (s) = -----------------------------------------------------------------------------------------------------
System Clock Frequency (Hz)
Continuous Mode
In Continuous mode, the timer counts up to the 16-bit Reload value stored in the Timer
Reload High and Low Byte registers. The timer input is the system clock. Upon reaching
the Reload value, the timer generates an interrupt, the count value in the Timer High and
Low Byte registers is reset to 0001Hand counting resumes. 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 timer Reload.
The steps for configuring a timer for Continuous mode and initiating the count are as fol-
lows:
1. Write to the Timer Control register to:
–
–
–
Disable the timer
Configure the timer for Continuous mode.
Set the prescale value.
PS017610-0404
Timers
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