Acces PAD128 User Manual - page 25
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Manual MPAD128.D1g
Bit D1 is a pause bit. If this bit is set on a point, the chip will stop acquiring points after
finishing that point. It will set the Start bit (D0 of Base+10) to 0. Restart at the next
point by setting the Start bit to 1.
Bit D0, Loop, is set on the last point you set up. If you only want to acquire data from
three channels, you would have three points, and the last one (at Base+4) would have
Loop set. When the A/D takes data, it will read point 0, point 1, point 2, point 0, point
1, etc.
Reading these base addresses will return the values last written.
Base Address + 10, A/D Control Register
DF
DE
DD
DC
DB
DA
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
unused don’t care
D
ia
g
0
0
0
0
0
si
g
n
/c
h
0
Cal
Z
e
ro
R
e
se
t
S
ta
rt
The highlighted bits are the ones you will use most often, the rest can be set to 0 for
normal operation.
Bits DF through DC are unused, and the card will ignore the values set. It is generally
recommended to set these bits to zero for compatibility with future design
enhancements.
Bit DB, Diag, places the chip in diagnostic mode. In this mode, the channel numbers
take on special meaning, allowing readback of various reference and ground voltages.
When Diag is set, CH+ set to 000 selected VREFOut, 001 selects Vref+, the remaining
settings indicate channels as normal. Also, CH- set to 001 indicates VRef-, while the
remaining codes indicate channels as normal. This mode can be used to verify the
device is providing a valid VRefOut and that VRef± are okay. Normally this bit will
be set to 0.
Bits DA through D6 are reserved for advanced functions. Refer to the LM12H458 chip
specification for more information.
Bit D5, sign/ch, sets the format of returned analog data. If the bit is cleared to 0, the
data word will contain the point responsible for the data in bits F-C. If the bits is set to
1, bits F-C of the data will contain the sign bit from the conversion. See Base+18 for
more information on data format.
Bit D4 is reserved for advanced functions. Refer to the LM12H458 chip specification
for more information.
Bit D3, cal, set to 1 starts a full calibration. This process takes less than 1 ms, calibrates
an internal offset correction coefficient based on the average of eight samples, and