AD7280ABSTZ datasheet(37/48 Pages) AD

37 / 48 page

AD7280A

Rev. 0 | Page 37 of 48

CRC Calculation Example 3

This example shows the breakdown of a 32-bit register read

from the low byte of the control register of the master device,

that is, Device 0.

The CRC is computed in the AD7280A on Bits[D31:D10], that

is, the device address, the register address, the register data, two

reserved zero bits, and the write acknowledge bit. The

calculated CRC is sent along with Bits[D31:D10] and

Bits[D1:D0] to the DSP/microprocessor.

The data received from the AD7280A is as follows:

0000 0001 1100 0010 1000 0110 0110 1000 (0x01C28668).

•

Device address: 00000 (0x00)

•

Reserved 0s: 0 (0x0)

•

Write acknowledge: 1 (0x1)

•

CRC: 10011010 (0x9A)

•

Reserved 0s: 0 (0x0)

The CRC bits are computed again in the DSP/microprocessor

on Bits[D31:D10] of the data that is read back from the AD7280A.

The data input to the CRC algorithm is, therefore,

0000000111000010100001 (0x0070A1).

Following the completion of the calculation, the value of

CRC_7 to CRC_0 is 10011010 (0x9A). This result matches

the CRC that was sent from the AD7280A; therefore, this

transmission of data is valid.

CRC Calculation Example 4

This example shows the breakdown of a 32-bit conversion result

read from the Cell Voltage 3 conversion result register of Device 1.

The CRC is computed in the AD7280A on Bits[D31:D10], that

is, the device address, the channel address, the conversion data,

and the write acknowledge bit. The calculated CRC is sent along

with Bits[D31:D10] and Bits[D1:D0] to the DSP/microprocessor.

The data received from the AD7280A is as follows:

1000 0001 0100 1100 1101 0101 0001 1000 (0x814CD518).

•

Device address (read LSB first): 10000 (0x10)

•

Channel address: 0010 (0x2)

•

Conversion data: 100110011010 (0x99A)

•

Write acknowledge: 1 (0x1)

•

CRC: 01000110 (0x46)

•

Reserved 0s: 0 (0x0)

The CRC bits are computed again in the DSP/microprocessor

on Bits[D31:D10] of the data that is read back from the

AD7280A. The data input to the CRC algorithm is, therefore,

1000000101001100110101 (0x205335).

Following the completion of the calculation, the value of

CRC_7 to CRC_0 is 01000110 (0x46). This result matches

the CRC that was sent from the AD7280A; therefore, this

transmission of data is valid.

AD7280ABSTZ Datasheet(PDF) 37 Page - Analog Devices

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