Measurement-computing PC104-DIO48 Manual do Utilizador descarregar pdf (Página 11)

The method of programming required to set/read bits from bytes is

beyond the scope of this manual. It is covered in most Introduction To

Programming books.

Board registers and their function are listed on the following table. Each

eight individual read/write functions.

Table 3-2. Board I/O Addresses

Configure 2nd 82C55None. No read back on

82C55

BASE + 7

Port C OutputPort C InputBASE + 6

Port B OutputPort B InputBASE + 5

Port A Output (2nd 8255)Port A Input of 2nd 82C55BASE + 4

Configure 1st 82C55None. No read back on

82C55

BASE + 3

Port C OutputPort C InputBASE + 2

Port B OutputPort B InputBASE + 1

Port A Output (1st 8255) Port A Input of 1st 82C55BASE + 0

WRITE FUNCTIONREAD FUNCTIONADDRESS

3.1 DIGITAL I/O REGISTERS

PORT A DATA

BASE ADDRESS + 0 (1st 82C55)

BASE ADDRESS + 4 (2nd 82C55)

A0A1A2A3A4A5A6A7

01234567

PORT B DATA

BASE ADDRESS + 1 (1st 82C55)

BASE ADDRESS + 5 (2nd 82C55)

B0B1B2B3B4B5B6B7

01234567

Ports A & B may be programmed as input or output. Each is written to

and read from in bytes, although for control and monitoring purposes,

individual bits are typically used.

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 23 24

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Measurement-computing PC104-DIO48 Manual do Utilizador Página 11