Z8F0830HH020SG Datasheet, PDF (88/257 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore!^® F0830 Series
Product Specification
70
reload. For the timer output to make a state change at a ONE-SHOT time-out (rather than
a single cycle pulse), first set the TPOL bit in the Timer Control Register to the start value
before enabling ONE-SHOT Mode. After starting the timer, set TPOL to the opposite bit
value.
Observe the following steps for configuring a timer for ONE-SHOT Mode and for initiat-
ing the count:
1. Write to the Timer Control Register to:
– Disable the timer
– Configure the timer for ONE-SHOT Mode
– Set the prescale value
– Set the initial output level (High or Low) if using the timer output Alternate func-
tion
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 appropriate, 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 calculated with the following equation:
One-Shot Mode Time-Out Period (s) = ^---R----e---l-o---a---d----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)
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 0001H and the counting resumes. Additionally, if
the timer output alternate function is enabled, the timer output pin changes state (from
Low to High or from High to Low) at timer reload.
Observe the following steps for configuring a timer for CONTINUOUS Mode and for ini-
tiating the count:
1. Write to the Timer Control Register to:
PS025113-1212
Operation