B&B Electronics PCI-1711 - Manual - Manual (Page 101)

Appendix D
– 93 – PCI-1710 series User’s Manual Advantech Co., Ltd.
www.advantech.com
Appendix
D
D. 82C54 Counter Function
D.1 The Intel 82C54
The PCI-1710/1710L/1710HG/1710HGL/1711/1711L/1716/1716L uses
one Intel 82C54 compatible programmable interval timer/counter chip.
The popular 82C54 offers three independent 16-bit counters, counter 0,
counter 1 and counter 2. Each counter has a clock input, control gate
and an output. You can program each counter for maximum count
values from 2 to 65535.
The 82C54 has a maximum input clock frequency of 10 MHz. The PCI-
1710/1710L/1710HG/1710HGL/1711/1711L/1716/1716L provides 10
MHz input frequencies to the counter chip from an on-board crystal
oscillator.
Counter 0
On the PCI-1710/1710L/1710HG/1710HGL/1711/1711L/1716/1716L ,
counter 0 can be a 16-bit timer or an event counter, selectable by users.
When the clock source is set as an internal source, counter 0 is a 16-bit
timer; when set as an external source, then counter 0 is an event
counter and the clock source comes from CNT0_CLK. The counter is
controlled by CNT0_GATE. When CNT0_GATE input is high, counter
0 will begin to count.
Counter 1 & 2
Counter 1 and counter 2 of the counter chip are cascaded to create a
32-bit timer for the pacer trigger. A low-to-high edge of counter 2
output (PACER_OUT) will trigger an A/D conversion. At the same
time, you can use this signal as a synchronous signal for other
applications.