Z8F4822AR020SG Datasheet, PDF (84/323 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F64xx Series
Product Specification
64
it is appropriate to have the timer output make a permanent state change upon a One-Shot
time-out, first set the TPOL bit in the Timer Control 1 Register to the start value before
beginning ONE-SHOT Mode. Then, after starting the timer, set TPOL to the opposite bit
value.
Observe the following procedure for configuring a timer for ONE-SHOT Mode and initi-
ating the count:
1. Write to the Timer Control 1 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 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 1 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 using 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 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.
Observe the following procedure for configuring a timer for CONTINUOUS Mode and
initiating the count:
1. Write to the Timer Control 1 Register to:
PS019924-0113
PRELIMINARY
Operation