Datasheet

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)
• Register address: 001110 (0x0E)
• Register data: 00010100 (0x14)
• 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.