Z8FMC16100 Series Flash MCU
Product Specification
101
Compare Mode
In COMPARE mode, the timer counts up to the 16-bit compare value stored in the Timer
Reload High and Low Byte registers. After reaching the compare value, the timer gener-
ates an interrupt and counting continues (the timer value is not reset to 0001h). If the
Timer Output alternate function is enabled, the Timer Output pin changes state (from Low
to High or from High to Low).
If the timer reaches FFFFh, the timer rolls over to 0000hand continues counting.
The steps for configuring a timer for COMPARE mode and initiating the count are as fol-
lows:
1. Write to the Timer Control registers to:
a. Disable the timer.
b. Configure the timer for COMPARE mode.
c. Set the prescale value.
d. Set the initial logic level (High or Low) for the Timer Output alternate function, if
appropriate.
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 Compare 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.
The compare time is calculated by the following equation (Start Value is typically = 1):
(Compare Value – Start Value +1) x Prescale
Compare Mode Time (s) =
System Clock Frequency (Hz)
Gated Mode
In GATED mode, the timer counts only when the Timer Input signal is in its active state,
as determined by the TPOLbit in the Timer Control 1 Register. When the Timer Input sig-
nal is active, counting begins. A timer interrupt is generated when the Timer Input signal
transitions from active to inactive state, a timer reload occurs, or both, depending on
TICONFIG[1:0]. To determine if a Timer Input signal deassertion generated the inter-
rupt, read the associated GPIO input value and compare it to the value stored in the TPOL
bit.
PS024604-1005
P R E L I M I N A R Y
Timer Operating Modes
ZILOG [ ZILOG, INC. ]
