AD7715_15 datasheet(12/40 Pages) AD

12 / 40 page

AD7715

Rev. D | Page 12 of 40

ON-CHIP REGISTERS

The AD7715 contains four on-chip registers, which can be

accessed by via the serial port on the part. The first of these

is a communications register that decides whether the next

operation is a read or write operation and also decides which

cations to the part must start with a write operation to the

communications register. After power-on or RESET, the

device expects a write to its communications register. The data

written to this register determines whether the next operation

to the part is a write or a read operation and also determines to

which register this read or write operation occurs. Therefore,

write access to any of the other registers on the part starts with

a write operation to the communications register followed by a

write to the selected register. A read operation from any register

on the part (including the communications register itself and

the output data register) starts with a write operation to the

communications register followed by a read operation from the

selected register. The communication register also controls the

standby mode and the operating gain of the part. The DRDY status

is also available by reading from the communications register. The

second register is a setup register that determines calibration

modes, filter selection and bipolar/unipolar operation. The

third register is the data register from which the output data

from the part is accessed. The final register is a test register

that is accessed when testing the device. It is advised that the

user does not attempt to access or change the contents of the

test register as it may lead to unspecified operation of the

device. The registers are discussed in more detail in the

following sections.

AD7715 Datasheet(PDF) 12 Page - Analog Devices