Specifications

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Appendix D. 82C54 Counter Chip
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.