Z8F6421PM020SC Datasheet, PDF (103/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
83
The steps for configuring a timer for GATED mode and initiating the count are as follows:
1. Write to the Timer Control 1 register to:
– Disable the timer
– Configure the timer for GATED mode
– Set the prescale value
2. Write to the Timer High and Low Byte registers to set the starting count value. This
only affects the first pass in GATED mode. After the first timer reset in GATED mode,
counting always begins at the reset value of 0001H.
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. Configure the associated GPIO port pin for the Timer Input alternate function.
6. Write to the Timer Control 1 register to enable the timer.
7. Assert the Timer Input signal to initiate the counting.
CAPTURE/COMPARE Mode
In CAPTURE/COMPARE mode, the timer begins counting on the first external Timer
Input transition. The desired transition (rising edge or falling edge) is set by the TPOL bit
in the Timer Control 1 Register. The timer input is the system clock.
Every subsequent desired transition (after the first) of the Timer Input signal captures the
current count value. The Capture value is written to the Timer PWM High and Low Byte
Registers. When the Capture event occurs, an interrupt is generated, the count value in the
Timer High and Low Byte registers is reset to 0001H, and counting resumes.
If no Capture event occurs, the timer counts up to the 16-bit Compare value stored in the
Timer Reload High and Low Byte registers. Upon reaching the Compare value, the timer
generates an interrupt, the count value in the Timer High and Low Byte registers is reset to
0001H and counting resumes.
The steps for configuring a timer for CAPTURE/COMPARE mode and initiating the
count are as follows:
1. Write to the Timer Control 1 register to:
– Disable the timer
– Configure the timer for CAPTURE/COMPARE mode
– Set the prescale value
– Set the Capture edge (rising or falling) for the Timer Input
2. Write to the Timer High and Low Byte registers to set the starting count value
(typically 0001H).
PS019915-1005
Timers