Analog Input Gain/Page Select/Scan Settings: Base+3 (Write)
Standard Mode:
00 = Page 0
01 = Page 1
10 = Page 2
Reset and Enhanced Mode:
00 = Page 0
01 = Page 0
10 = Page 0
Note: When the board is in standard mode, only page 0 can be accessed. The page
mode can only be set when the register map is in enhanced mode.
SCANEN
Scan mode enable.
1 = Each A/D trigger causes the board to generate an A/D conversion on each channel in the range
LOW – HIGH. The range is set with the channel register in Base+2.
The STS bit (Base+3, bit 7) stays high during the entire scan.
0 = Each A/D trigger causes the board to generate a single A/D conversion on the current channel.
The internal channel pointer increments to the next channel in the range LOW – HIGH or resets to
LOW, if the current channel is HIGH.
The STS bit (Base+3, bit 7) stays high during the A/D conversion.
G1-G0
Analog input gain. The gain is the ratio of the voltage seen by the A/D converter and the voltage
applied to the input pin. The gain setting is the same for all input channels.
•
When this register is written, the WAIT bit (Read Base+3, bit 6) goes high for
10 microseconds to indicate that the analog input circuit is settling. During
this time, an A/D conversion should not be performed because the data will be
inaccurate. After writing a new gain setting, the program should monitor the
WAIT bit prior to starting an A/D conversion.
•
After writing a new channel selection (Base+2), the WAIT bit is also set, and
the program must monitor it prior to starting an A/D conversion.
•
The channel and gain registers can be written to in succession without waiting
for the intervening WAIT signal. Only one WAIT period must be observed
between the last triggering condition (write to Base+2 or Base+3) and the start
of an A/D conversion.
•
The following table lists the possible analog input ranges.
G1
G0
Gain
Unipolar Range
Bipolar Range
0
0
1
Invalid
±10V
0
1
2
0 - 8.3V
±5V
1
0
4
0 - 5 V
±2.5V
1
1
8
0 - 2.5V
±1.25V
Diamond Systems Corporation
Athena II User Manual
Page 57