Measurement-computing CIO-DAS08-PGH User Manual download pdf (Page 18)

4.2 A/D DATA REGISTER

BASE ADDRESS (Read / Write)

0000A/D12 LSBA/D11A/D10A/D9

01234567

READ

On read, it contains the least significant four digits of the analog input data.

These four bits of analog input data must be combined with the eight bits of analog input data in BASE + 1, forming a complete

12 bit number. The data is in the format 0 = minus full scale. 4095 = +FS.

WRITE

Writing any data to the register causes an immediate 8-bit A/D conversion.

BASE + 1 (Read / Write)

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

01234567

READ

On read, the most significant A/D byte is read.

The A/D Bits code corresponds to the voltage on the input according to the table below.

0 Volts

−

Full Scale

½ Full Scale0 Volts8002048

+Full Scale+Full ScaleFFF4095

UNIPOLARBIPOLARHEXDECIMAL

WRITE

Writing to this register starts a 12-bit A/D conversion.

A note of caution: Place several NO-OP instructions between consecutive 12-bit A/D conversions to avoid over-running the A/D

converter.

4.3 STATUS AND CONTROL REGISTER

BASE + 2 (Read / Write) Read Functions

MUX0MUX1MUX2IRQIP1IP2IP3EOC

01234567

READ = STATUS

EOC = 1 the A/D is busy converting and data should not be read.

EOC = 0 the A/D is not busy and data can be read.

IP3 to IP1 are the digital input lines on the 37 pin analog connector.

IRQ is the status of an edge triggered latch connected to Interrupt Input (pin 24) of the analog connector. It is high (1) when a

positive edge has been detected. It can be reset to 0 by writing to the INTE mask at BASE + 2 write.

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 ... 27 28

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Measurement-computing CIO-DAS08-PGH User Manual Page 18