Measurement-computing PC104-AC5 Bedienungsanleitung PDF herunterladen (Seite 11)

In summary form, the registers and their function are listed on the following table.

Within each register are eight bits which may constitute a byte of data or eight

individual bit set/read functions.

Table 3-1. Board Register Functions

Configure I/ONone. BASE +3

1st Port C Output1st Port C InputBASE +2

1st Port B Output1st Port B InputBASE +1

1st Port A Output1st Port A Input BASE +0

WRITE FUNCTIONREAD FUNCTIONADDRESS

3.2 DIGITAL DATA REGISTERS

Port A

Base Address + 0

A0A1A2A3A4A5A6A7

01234567

Port B Data

Base Address +1

B0B1B2B3B4B5B6B7

01234567

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

in bytes, but for control and monitoring, use individual bits.

When using bit set/reset and bit read functions, unwanted bits must be masked out of

reads and ORed into writes.

Port C Data

Base Address +2

CL0CL1CL2CL3CH0CH1CH2CH3

C0C1C2C3C4C5C6C7

01234567

Port C may be used as one 8-bit port of either input or output, or it may be split into

two 4-bit ports which may be independently input or output. The notation for the

upper 4-bit port is CH3 - CH0, and for the lower, CL3 - CL0.

Although it may be split, every read and write to port C carries eight bits of data so

unwanted information must be ANDed out of reads, and writes must be ORed with the

current status of the other port.

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Measurement-computing PC104-AC5 Bedienungsanleitung Seite 11