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AD7329
Data Sheet
Rev. B | Page 26 of 40
CONTROL REGISTER
The control register is used to select the analog input channel, analog input configuration, reference, coding, and power mode. The
control register is a write-only, 12-bit register. Data loaded on the DIN line corresponds to th
e AD7329 configuration for the next
conversion. If the sequence register is being used, data should be loaded into the control register after the range registers and the sequence
register have been initialized. The bit functions of the control register are described i
n Table 11 (the power-up status of all bits is 0).
MSB
LSB
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Write
Register
Select 1
Register
Select 2
ADD2
ADD1
ADD0
Mode 1
Mode 0
PM1
PM0
Coding
REF
SEQ1
SEQ2
Weak/
Three-State
0
Table 11. Control Register Details
Bit
Mnemonic
Description
12, 11, 10
ADD2, ADD1,
ADD0
These three channel address bits are used to select the analog input channel for the next conversion if the
sequencer is not being used. If the sequencer is being used, the three channel address bits are used to
select the final channel in a consecutive sequence.
9, 8
Mode 1, Mode 0
These two mode bits are used to select the configuration of the eight analog input pins, VIN0 to VIN7. These
pins are used in conjunction with the channel address bits. On t
he AD7329, the analog inputs can be
configured as eight single-ended inputs, four fully differential input pairs, four pseudo differential inputs,
7, 6
PM1, PM0
5
Coding
This bit is used to select the type of output coding that t
he AD7329 uses for the next conversion result.
If coding = 0, the output coding is twos complement. If coding = 1, the output coding is straight binary.
When operating in sequence mode, the output coding for each channel is the value written to the coding
bit during the last write to the control register.
4
REF
The reference bit is used to enable or disable the internal reference. If REF = 0, the external reference is
enabled and used for the next conversion and the internal reference is disabled. If REF = 1, the internal ref-
erence is used for the next conversion. When operating in sequence mode, the reference used for each
channel is the value written to the REF bit during the last write to the control register.
3, 2
SEQ1/SEQ2
The Sequence 1 and Sequence 2 bits are used to control the operation of the sequencer (s
ee Table 14).1
Weak/Three-State
This bit selects the state of the DOUT line at the end of the current serial transfer. If the bit is set to 1, the
DOUT line is weakly driven to Channel Address Bit ADD2 of the following conversion. If this bit is set to 0,
The eight analog input channels can be configured as seven pseudo differential analog inputs, four pseudo differential inputs, four true
differential input pairs, or eight single-ended analog inputs.
Table 12. Analog Input Configuration Selection
7 Pseudo Differential I/Ps
4 Fully Differential I/Ps
4 Pseudo Differential I/Ps
8 Single-Ended I/Ps
Channel Address Bits
(Mode 1 = 1, Mode 0 = 1)
(Mode 1 = 1, Mode 0 = 0)
(Mode 1 = 0, Mode 0 =1)
(Mode 1 = 0, Mode 0 = 0)
ADD2
ADD1
ADD0
VIN+
VIN
VIN+
VIN
VIN+
VIN
VIN+
VIN
0
VIN0
VIN7
VIN0
VIN1
VIN0
VIN1
VIN0
AGND
0
1
VIN1
VIN7
VIN0
VIN1
VIN0
VIN1
AGND
0
1
0
VIN2
VIN7
VIN2
VIN3
VIN2
VIN3
VIN2
AGND
0
1
VIN3
VIN7
VIN2
VIN3
VIN2
VIN3
AGND
1
0
VIN4
VIN7
VIN4
VIN5
VIN4
VIN5
VIN4
AGND
1
0
1
VIN5
VIN7
VIN4
VIN5
VIN4
VIN5
AGND
1
0
VIN6
VIN7
VIN6
VIN7
VIN6
VIN7
VIN6
AGND
1
Temperature indicator
VIN6
VIN7
VIN6
VIN7
AGND