Device Features

Overall Features:

72 TTL level digital I/O lines.

Emulates mode 0 of 8255 PPI

Buffered circuits provide higher driving capability

Interrupt handling

Interrupt output pin for simultaneously triggering external devices with the interrupt

High density 100-pin SCSI- female connector

Output status readback

Two 16-bit timers can be cascaded to one 32-bit timer, and can generate watchdog timer interrupts

Three event counter can generate event interrupts

Keeps port I/O settings and digital output states after hot system reset

Supports dry contact and wet contact

Applications

Industrial AC/DC I/O devices monitoring and control

Relay and switch monitoring and control

Parallel data transfer

Sensing the signals of TTL, DTL, CMOS logic

Driving indicator LEDs

Interrupt Function:

Two lines in each I/O port (C0 and C4) and three counters outputs (Timer 0, Timer 1 and Counter 2) are connected to the interrupt circuitry. The "Interrupt Control Register" of the MIC-3751 controls how the combination of the 9 signals generates an interrupt. Three interrupt request signals can be generated at the same time, and then the software can service these three request signals by ISR. The dual interrupt sources provide the card with more capability and flexibility.

Timer and Counter:

The MIC-3751 includes one 8254 compatible programmable timer/counter chip which provides three 16-bit counters. Each has 6 operation modes. Counter0 and Counter1 can be used separately as Timer0 and Timer1 or can be cascaded to create one 32-bit timer. Both Timer 0, Timer 1 and Counter 2 can generate interrupts to the computer. Please refer to hardware manual for more information on the operation modes of the counter chip.