Z86318 Datasheet, PDF (18/26 Pages) Zilog, Inc. – Z8 MCU 8-BIT MICROCONTROLLER

Z86318
Z8^® MCU 8-Bit Microcontroller
FUNCTIONAL DESCRIPTION (Continued)
The counter can be programmed to start, stop, restart to
continue, or restart from the initial value. The counters can
also be programmed to stop upon reaching zero (single
pass mode) or to automatically reload the initial value and
continue counting (modulo-n continuous mode).
The counters, but not the prescalers, may be read at any
time without disturbing their value or count mode. The
clock source for T1 is user-definable and can be either the
internal microprocessor clock divided by four, or an exter-
nal signal input via Port 3. The Timer Mode register config-
ures the external timer input (P31) as an external clock, a
trigger input that is retriggerable or not retriggerable, or as
a gate input for the internal clock.
OSC
Internal
Clock
External Clock
Clock
Logic
÷4
Internal Data Bus
Write
Write
Read
PRE0
Initial Value
Register
T0
Initial Value
Register
T0
Current Value
Register
6-Bit
÷4
Down
Counter
8-Bit
Down
Counter
IRQ4
6-Bit
Down
Counter
8-Bit
Down
Counter
IRQ5
T_IN P31
Internal Clock
Gated Clock
Triggered Clock
PRE1
Initial Value
Register
T1
Initial Value
Register
T1
Current Value
Register
Write
Write
Read
Internal Data Bus
Figure 15. Counter/Timers Block Diagram
18
PRELIMINARY