User`s guide

Installation  15
Figure 2.8 IRQ Level Setting
2.10 Clock Source Setting
The 8254 programmable interval timer is used in the ACL-8316/12. It
provides 3 independent channels of 16-bit programmable down counters. The
input of counter 2 is connected to a precision 2MHz oscillator for internal
pacer. The input of counter 1 is cascaded from the output of counter 2. The
channel 0 is free for user's applications. There are two selections for the
clock source of channel 0: the internal 2MHz clock or the external clock signal
from connector CN3 pin 37. The setting of clock is shown as Figure 2.9.
Internal Clock
Source : 2MHz
(default setting)
External Clock
Source
( Pin-37 of CN3)
INTCLK
JP4
EXTCLK
INTCLK
JP4
EXTCLK
Figure 2.9 Timer's Clock Source Setting