Operation of The Card
Page 17
Blue Chip Technology Ltd.
01270146.doc
Page 17
DAC Section
The Digital to Analogue converter is accessed as 4 ports. These ports are
mapped into the PC at the following addresses.
BASE
+ 0
DAC Control register
+ 1
Channel enable register 1
+ 2
Channel enable register 3
+ 3
DAC output register
The DAC is 12 bits wide, therefore two write operations are required to the
DAC output register to load the required value. The low 8 bits are sent first
followed by the high 4 bits.
Output Value
Output Voltage
0
-10 V
2048
0 V
4095
+10 V
The DAC section operates in one of two basic modes, I/O or DMA.
To send data to the DAC in I/O mode use the following sequence:
Initialise the timer (see Timer Initialisation above).
Write 0 to BASE + 1 and BASE + 2, this enables all the channels.
Read BASE + 0 , this resets the internal state machine.
Write the low 8 bits of the DAC data into BASE + 3.
Write the high 4 bits of the DAC data into BASE + 3.
Write the channel number to update (1 to 12) to BASE + 0.
Write 0 to BASE + 0.
Summary of Contents for AOP-12D
Page 1: ...AOP 12D Multi Function Analogue Output Card User Manual...
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