Data Sheet

AD7322

Rev. B | Page 21 of 36

REGISTERS

The AD7322 has two programmable registers, the control

register and the range register. These registers are write-only

registers.

ADDRESSING REGISTERS

A serial transfer on the AD7322 consists of 16 SCLK cycles. The

three MSBs on the DIN line during the 16 SCLK transfer are

decoded to determine which register is addressed. The three

MSBs consist of the write bit, zero bit, and register select bit.

The register select bit is used to determine which of the two on-

board registers is selected. The write bit determines if the data

on the DIN line following the register select bit loads into the

addressed register. If the write bit is 1, the bits are loaded into

the register addressed by the register select bits. If the write bit

is 0, the data on the DIN line does not load into any register.

The zero bit must always be set to 0.

Combinations of the write bit, the zero bit, and the register

select bit other than those specified in Table 8 access registers

for Analog Devices internal use only. Do not access these registers,

as doing so may lead to unspecified operation of the device.

Table 8. Decoding Register Select Bit and Write Bit

Write

Zero

Register Select

Comment

0

0

X

Data on the DIN line during this serial transfer is ignored. Register contents remain unchanged.

1

0

0

This combination selects the control register. The subsequent 12 bits are loaded into the control register.

1

0

1

This combination selects the range register. The subsequent six bits are loaded into the range register.