Measurement-computing CIO-DAS08-PGH User Manual download pdf (Page 17)

4: REGISTER ARCHITECTURE

4.1 CONTROL & DATA REGISTERS

The CIO-DAS08-PGx is controlled and monitored by writing to and reading from eight consecutive 8-bit I/O addresses. The first

address, or BASE ADDRESS, is determined by setting a bank of switches on the board.

Register manipulation is best left to experienced programmerss as most of the possible functions are implemented in easy to use

Universal Library™.

The register descriptions follow the format:

A/D8A/D7A/D6A/D5A/D4A/D3A/D2A/D1

01234567

Where the numbers along the top row are the bit positions within the 8-bit byte and the numbers and symbols in the bottom row is

the function associated with each bit.

To write to or read from a register in decimal or HEX, the bit weights listed in table 4-1 apply.

Table 4-1. Register Bit Weights

801287

40646

20325

10164

883

442

221

110

HEX VALUEDECIMAL VALUEBIT POSITION

To write control words or data to a register, the individual bits must be set to 0 or 1 then combined to form a byte.

The method of programming required to read/write bits from bytes is beyond the scope of this manual.

In summary form, the registers and their function are listed in Table 4-2. Each register has eight bits which may constitute a byte

of data or eight individual bit read/write functions.

Table 4-2. Board Register Functions

Counter ControlNot UsedBASE +7

Load Counter 2Read Counter 2BASE +6

Load Counter 1Read Counter 1BASE +5

Load Counter 0Read Counter 0BASE +4

Programmable Gain ControlChannel MUX and Gain StatusBASE +3

OP1-OP4, INTE & MUX

Address

EOC, IP1-IP3, IRQ, MUX

Address

BASE +2

Start 12 Bit A/D ConversionA/D Bits 1(MSB)-8BASE +1

Start 8 Bit A/D ConversionA/D Bits 9-12 (LSB)BASE

WRITE FUNCTIONREAD FUNCTIONADDRESS

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 27 28

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Measurement-computing CIO-DAS08-PGH User Manual Page 17