Measurement Computing PC104-DAS08 - Manual (Page 14)

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 Table 4-3.
Table 3-3. A/D Bit Codes
0 Volts
−
Full Scale 0 0
½ Full Scale 0 Volts 800 2048
+Full Scale + Full Scale FFF 4095
UNIPOLAR BIPOLAR HEX DECIMAL
WRITE
Writing to this register starts a 12-bit A/D conversion.
Note: Place several NO-OP instructions between consecutive 12-bit A/D conversions
to avoid over-running the A/D converter.
3.3 STATUS AND CONTROL REGISTER
BASE ADDRESS + 2
This register address is two registers, one is read active and one is write active.
READ = STATUS
MUX0 MUX1 MUX2 IRQ IP1 IP2 IP3 EOC
0 1 2 3 4 5 6 7
EOC = 1 the A/D is busy converting and data should not be read.
EOC = 0 the A/D is not busy and data may be read.
IP3 to IP1 are the digital input lines.
IRQ is the status of an edge triggered latch connected to the “Interrupt Req” pin on
the analog connector. It is high (1) when a positive edge has been detected. It may
be reset to 0 by writing to the INTE mask at BASE + 2 write.
MUX 2 to MUX 0 is the current multiplexer channel. The current channel is a
binary coded number between 0 and 7 .
WRITE = CONTROL
MUX0 MUX1 MUX2 INTE OP1 OP2 OP3 OP4
0 1 2 3 4 5 6 7
OP4 to OP1 are the digital output lines.
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