Athena IIII User Manual Rev A.00
www.diamondsystems.com
Page
47
Base + 3
Write
Analog Input Gain / Page Control
Bit No.
7
6
5
4
3
2
1
0
Name
X
X
PG1
PG0
X
SCANEN
ADG1
ADG0
Reset
0
0
0
0
0
0
0
0
PG1-PG0 Page Select (0 - 2): Only accessible when the board is configured on Enhanced Mode. When the
board is on standard mode, only page 0 can be accessed.
SCANEN
Scan mode enable:
1
Each A/D trigger will cause 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 (read Base + 3 bit 7) stays high during the entire scan. The time between A/D samples
is determined by the SCANINT bit in page 2. If SCANINT=0, the scan interval is 10us,
and if SCANINT=1, the scan interval is 5us.
0
Each A/D trigger will cause the board to generate a single A/D conversion on the current
channel. The internal channel pointer will increment to the next channel in the range
LOW
– HIGH or reset to LOW if the current channel is HIGH. The STS bit stays high
during the A/D conversion.
ADG1-0
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 to, the ADWAIT bit (Read Base + 3 bit 5) will go 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 ADWAIT bit prior to
starting an A/D conversion.
After writing a new channel selection (Base + 2), the ADWAIT 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 ADWAIT signal.
Only one ADWAIT 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:
ADG1 ADG0
Gain
Unipolar Range
Bipolar Range
0
0
1
0-10V
±10V
0
1
2
0-5V
±5V
1
0
4
0-2.5V
±2.5V
1
1
8
0-1.25V
±1.25V