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PAD128 Manual
Page 6-2
Manual MPAD128.D1g
Base A 0 Through Base A E (Even), Point Setup
Registers
DF DE DD DC DB DA D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
SettleTime, use 0000 0 0
ti
m
e
r
0 CH-, use 000 CH+
p
a
u
se
lo
o
p
The highlighted bits are the ones you will use most often, the rest can be set to 0 for
normal operation.
These eight word-sized registers contain the list of channels from which you wish to
acquire data. The list is an ordered array of contiguous points, where the first entry (at
base+0) indicates the first channel you wish to acquire. The second entry (at base+2)
through the eighth entry (Base+E) are optional and indicate further channels you wish
to acquire in the order you wish to acquire them. No registers may be skipped. For
example, if you wish to acquire channels 1 and 5, the entries would be set in Base+0 and
Base+2, not base+4 and Base+A.
The last channel's entry should have the loop bit (D0) set to allow the A/D to start over
at the beginning of the list.
Bits DF through DC, SettleTime, are optional, use 0000 for most input sources. If a
larger settle time is desired, for example for source impedances (R) greater than 100
ohms, the following equation will calculate the necessary setting for these bits (D):
D = 3.33 x R (round up to nearest integer)
Bits DB, DA and D8 are reserved for advanced functions. Refer to the LM12H458 chip
specification for more information.
Bit D9 is the timer bit. When bit 9 is set to 1, the A/D chip will halt until the duration
programmed in Base + 16 elapses. After the timeout elapses, operation will continue
at the next point.
Bits D7 through D5, CH-, select the low-side analog input channel. For single-ended
use, set these bits to 000. Any other setting configures the point for differential, where
the values 001 through 111 indicate which channel (1-7) is to be used for the low side
of the differential analog input.
Bits D4 through D2, CH+, indicate the high-side analog input channel. For most
applications place a bit pattern from 000 to 111 to indicate which channel (0-7) you
want this point to acquire. When CH- is set to anything other than 000, CH+ selects the
high side of the differential analog input channel.