Z86C8316PEC ZILOG [Zilog, Inc.], Z86C8316PEC Datasheet - Page 25

• Manufacturer Part Number: Z86C8316PEC
• Description: Z8 MCU MICROCONTROLLERS
• Manufacturer: ZILOG [Zilog, Inc.]

Z86C83/C84
Z8
FUNCTIONAL DESCRIPTION (Continued)
Counter/Timers. There are two 8-bit programmable
counter/timers (T0-T1), each driven by its own 6-bit
programmable prescaler. The T1 prescaler is driven by
internal or external clock sources; however, the T0
prescaler is driven by the internal clock only (Figure 19).
The 6-bit prescalers can divide the input frequency of the
clock source by any integer number from 1 to 64. Each
prescaler drives its counter, which decrements the value
(1 to 256) that has been loaded into the counter. When the
counter reaches the end of the count, a timer interrupt
request, IRQ4 (T0) or IRQ5 (T1), is generated.
The counters can be programmed to start, stop, restart to
continue, or restart from the initial value. The counters can
25
®
MCU Microcontrollers
D0 (SMR)
D1 (SMR)
TIN P31
Clock
Logic
OSC
16
2
External Clock
Internal Clock
Gated Clock
Triggered Clock
Internal
Clock
4
Figure 19. Counter/Timer Block Diagram
4
Write
Write
Initial Value
Initial Value
Register
Register
Counter
Counter
PRE0
PRE1
Down
Down
6-Bit
6-Bit
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 , are read at any
time without disturbing their value or count mode. The
clock source for T1 is user-definable and is either the
internal microprocessor clock divide-by-four, or an
external signal input through Port 3. The Timer Mode
register configures the external timer input (P31) as an
external clock, a trigger input that can be retriggerable or
non-retriggerable, or as a gate input for the internal clock.
The counter/timers can be cascaded by connecting the T0
output to the input of T1. T
R243 PRE1 Bit D1 to 0.
Write
Write
Internal Data Bus
Internal Data Bus
Initial Value
Initial Value
Register
Register
Counter
Counter
Down
Down
8-Bit
8-bit
T0
T1
Read
Read
2
Current Value
Current Value
Register
Register
IN
T0
T1
Mode is enabled by setting
TOUT
IRQ5
IRQ4
P36
DS96DZ80203