16.DIGITAL I/O OPERATION

Diamond-MM-32DX-AT contains two sets of digital I/O lines:

  • An internal 82C55-type digital I/O circuit provides 24 digital I/O lines that emulate the function of Mode 0 of an 8255 chip. These lines are buffered to provide extra drive current in output mode and are available on digital I/O header J4 on the left side of the board.

  • Analog I/O header J3 on the right side of the board contains 4 inputs and 3 outputs that can be used for general purpose DIO as long as they are not used for any special functions.

16.1 Main Digital I/O on J4: Internal 82C55 Circuit

16.2 Digital I/O Configuration Register

16.3 Mode 0 Digital I/O

16.4 Mode 1 Digital I/O With Handshaking

16.5 Auxiliary Digital I/O on J3

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