LRI2K-W4/3GE STMicroelectronics, LRI2K-W4/3GE Datasheet - Page 82

• Manufacturer Part Number: LRI2K-W4/3GE
• Description: IC EEPROM 2048BIT 97PF 8UFDFPN
• Manufacturer: STMicroelectronics

Specifications of LRI2K-W4/3GE

• Rf Type: Read / Write
• Frequency: 13.56MHz
• Features: ISO15693, ISO18000-3
• Package / Case: 8-UFDFPN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CRC (Informative)
Appendix B
B.1
B.2
82/86
CRC error detection method
The cyclic redundancy check (CRC) is calculated on all data contained in a message, from
the start of the Flags through to the end of Data. The CRC is used from VCD to LRI2K and
from LRI2K to VCD.
Table 94.
To add extra protection against shifting errors, a further transformation on the calculated
CRC is made. The one’s complement of the calculated CRC is the value attached to the
message for transmission.
To check received messages the 2 CRC bytes are often also included in the re-calculation,
for ease of use. In this case, the expected value for the generated CRC is the residue
F0B8h.
CRC calculation example
This example in C language illustrates one method of calculating the CRC on a given set of
bytes comprising a message.
C-Example to calculate or check the CRC16 according to ISO/IEC 13239
#define
#define
#define
#define
#define
#define
void main()
{
4, 91h, 39h};
// calculate_or_check_crc = CHECK_CRC;// This could be an other
example
ISO/IEC 13239
unsigned char array_of_databytes[NUMBER_OF_BYTES + 2] = {1, 2, 3,
unsigned int
int
int
int
calculate_or_check_crc = CALC_CRC;
if (calculate_or_check_crc == CALC_CRC)
{
CRC type
number_of_databytes = NUMBER_OF_BYTES;
POLYNOMIAL8408h//
PRESET_VALUEFFFFh
CHECK_VALUEF0B8h
NUMBER_OF_BYTES4// Example: 4 data bytes
CALC_CRC1
CHECK_CRC0
CRC (Informative)
CRC definition
Length
16 bits
current_crc_value;
number_of_databytes = NUMBER_OF_BYTES;
calculate_or_check_crc;
i, j;
X
16
+ X
12
Polynomial
x^16 + x^12 + x^5 + 1
+ X
CRC definition
5
+ 1 = 8408h
Direction
Backward
Preset
FFFFh
Residue
F0B8h
LRI2K