User's Manual

Register-Level Programming Chapter 4
Lab-NB User Manual 4-14 © National Instruments Corporation
DAC Configuration Register
This register determines if data written to the DACs is in straight binary or two’s complement
form. It also configures the DACs to output data automatically at a rate controlled by counter A2
OR EXTUPDATE*. This feature is particularly useful for automatic waveform generation.
Address: Base address + 5 8000 (hex)
Type: Write-only
Word Size: 8-bit
Bit Map:
76543 210
X X X X TMRWGN1 TMRWGN
0
TWOSDA1 TWOSDA0
Bit Name Description
7–4 X Don’t care bits.
3 TMRWGN1 Timer Waveform Generation Enable Bit for DAC1—This bit is
used to enable timer waveform generation from DAC1. If this bit
is set, DAC1 updates its output at regular intervals as determined
by counter A2 or the EXTUPDATE* signal at the I/O connector.
If this bit is cleared, then the voltage output of DAC1 is updated as
soon as the data is loaded into its data register.
2 TMRWGN0 Timer Waveform Generation Enable Bit for DAC0—This bit is
used to enable timer waveform generation from DAC0. If this bit
is set, DAC0 updates its output at regular intervals as determined
by counter A2 or the EXTUPDATE* signal at the I/O connector.
If this bit is cleared, then the voltage output of DAC0 is updated as
soon as the data is loaded into its data register.
1 TWOSDA1 Binary Coding Scheme Select Bit for DAC1—This bit selects the
binary coding scheme used for the DAC1 data. If this bit is set, a
two's complement binary coding scheme is used for interpreting
the 12-bit data. Two’s complement is useful if a bipolar output
range is selected. If this bit is cleared, a straight binary coding
scheme is used. Straight binary is useful if a unipolar output range
is selected.
0 TWOSDA0 Binary Coding Scheme Select Bit for DAC0—This bit selects the
binary coding scheme used for the DAC0 data. If this bit is set, a
two’s complement binary coding scheme is used for interpreting
the 12-bit data. Two’s complement is useful if a bipolar output
range is selected. If this bit is cleared, a straight binary coding
scheme is used. Straight binary is useful if a unipolar output range
is selected.