Standard test vector
CRC implementations are commonly verified with the ASCII input 123456789.
- Input format
- ASCII
- Input
- 123456789
- Expected CRC
- 0x7E
- Residue
- 0x00
CRC-8 / I-CODE
Width8-bitRefInNoRefOutNoInput data9 bytesUTF-8 bytesText is converted to UTF-8 bytes.
Standard test string
Result
Similar CRC Algorithms
5 modelsBrowse all algorithms
Result is calculated from the current input. Check is the published verification value for the standard input 123456789. Click another algorithm to view its detail page.
CRC-8 / GSM-A
8-bitPoly 0x1DIn No Out No
Result
0x37
Check
0x37
CRC-8 / HITAG
8-bitPoly 0x1DIn No Out No
Result
0xB4
Check
0xB4
CRC-8 / I-CODE Current
8-bitPoly 0x1DIn No Out No
Result
0x7E
Check
0x7E
CRC-8 / MIFARE-MAD
8-bitPoly 0x1DIn No Out No
Result
0x99
Check
0x99
CRC-8 / SAE-J1850
8-bitPoly 0x1DIn No Out No
Result
0x4B
Check
0x4B
CRC Lookup Table
CRC-8 / I-CODE · Poly 0x1D · Init 0xFD · XorOut 0x00 · 256 entries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 Source Code
CRC-8 / I-CODE · Poly 0x1D · Init 0xFD · XorOut 0x00 · C · 56 lines
/*
* Model: CRC-8 / I-CODE (8-bit)
* Poly: 0x1D, Init: 0xFD, XorOut: 0x00
* CRC Table C Source Code & Lookup Table Generator
*/
#include <stdint.h>
#include <stddef.h>
const uint8_t crc_table[256] = {
0x00, 0x1D, 0x3A, 0x27, 0x74, 0x69, 0x4E, 0x53,
0xE8, 0xF5, 0xD2, 0xCF, 0x9C, 0x81, 0xA6, 0xBB,
0xCD, 0xD0, 0xF7, 0xEA, 0xB9, 0xA4, 0x83, 0x9E,
0x25, 0x38, 0x1F, 0x02, 0x51, 0x4C, 0x6B, 0x76,
0x87, 0x9A, 0xBD, 0xA0, 0xF3, 0xEE, 0xC9, 0xD4,
0x6F, 0x72, 0x55, 0x48, 0x1B, 0x06, 0x21, 0x3C,
0x4A, 0x57, 0x70, 0x6D, 0x3E, 0x23, 0x04, 0x19,
0xA2, 0xBF, 0x98, 0x85, 0xD6, 0xCB, 0xEC, 0xF1,
0x13, 0x0E, 0x29, 0x34, 0x67, 0x7A, 0x5D, 0x40,
0xFB, 0xE6, 0xC1, 0xDC, 0x8F, 0x92, 0xB5, 0xA8,
0xDE, 0xC3, 0xE4, 0xF9, 0xAA, 0xB7, 0x90, 0x8D,
0x36, 0x2B, 0x0C, 0x11, 0x42, 0x5F, 0x78, 0x65,
0x94, 0x89, 0xAE, 0xB3, 0xE0, 0xFD, 0xDA, 0xC7,
0x7C, 0x61, 0x46, 0x5B, 0x08, 0x15, 0x32, 0x2F,
0x59, 0x44, 0x63, 0x7E, 0x2D, 0x30, 0x17, 0x0A,
0xB1, 0xAC, 0x8B, 0x96, 0xC5, 0xD8, 0xFF, 0xE2,
0x26, 0x3B, 0x1C, 0x01, 0x52, 0x4F, 0x68, 0x75,
0xCE, 0xD3, 0xF4, 0xE9, 0xBA, 0xA7, 0x80, 0x9D,
0xEB, 0xF6, 0xD1, 0xCC, 0x9F, 0x82, 0xA5, 0xB8,
0x03, 0x1E, 0x39, 0x24, 0x77, 0x6A, 0x4D, 0x50,
0xA1, 0xBC, 0x9B, 0x86, 0xD5, 0xC8, 0xEF, 0xF2,
0x49, 0x54, 0x73, 0x6E, 0x3D, 0x20, 0x07, 0x1A,
0x6C, 0x71, 0x56, 0x4B, 0x18, 0x05, 0x22, 0x3F,
0x84, 0x99, 0xBE, 0xA3, 0xF0, 0xED, 0xCA, 0xD7,
0x35, 0x28, 0x0F, 0x12, 0x41, 0x5C, 0x7B, 0x66,
0xDD, 0xC0, 0xE7, 0xFA, 0xA9, 0xB4, 0x93, 0x8E,
0xF8, 0xE5, 0xC2, 0xDF, 0x8C, 0x91, 0xB6, 0xAB,
0x10, 0x0D, 0x2A, 0x37, 0x64, 0x79, 0x5E, 0x43,
0xB2, 0xAF, 0x88, 0x95, 0xC6, 0xDB, 0xFC, 0xE1,
0x5A, 0x47, 0x60, 0x7D, 0x2E, 0x33, 0x14, 0x09,
0x7F, 0x62, 0x45, 0x58, 0x0B, 0x16, 0x31, 0x2C,
0x97, 0x8A, 0xAD, 0xB0, 0xE3, 0xFE, 0xD9, 0xC4
};
uint8_t calculate_crc(const uint8_t *data, size_t length) {
uint8_t crc = 0xFD;
for (size_t i = 0; i < length; i++) {
#if 0
uint8_t idx = (uint8_t)(crc ^ data[i]);
crc = (crc >> 8) ^ crc_table[idx];
#else
uint8_t idx = (uint8_t)((crc >> 0) ^ data[i]);
crc = (crc << 8) ^ crc_table[idx];
#endif
}
return crc ^ 0x00;
}About CRC-8/I-CODE
CRC-8/I-CODE is an 8-bit CRC used with I-CODE identification products.
CRC-8/I-CODE is a 8-bit CRC model defined by polynomial 0x1D, an initial register value of 0xFD, and final XOR 0x00. It uses normal, non-reflected input and output processing.
Documented application context for this model includes RFID, I-CODE, Identification systems. The calculator above applies this exact parameter set to the current input; the published Check value below is instead the fixed verification result for ASCII 123456789.
Model characteristics
A model is identified by its complete parameter set, not its polynomial alone.
- Bit order
- Normal
- Register start
- 0xFD
- Final XOR
- 0x00
- Published check
- 0x7E
Implementation checks for CRC-8/I-CODE
- Use a 8-bit register and polynomial 0x1D.
- Initialize the register to 0xFD and use XorOut 0x00 exactly as listed; changing either value defines a different model.
- Verify the implementation with ASCII “123456789”; the expected result is 0x7E.
Continue with the main calculator, browse the algorithm catalog, compare models in the Algorithm Reference section, or generate a lookup table.
Complete CRC-8/I-CODE parameters
| Parameter | Value | Meaning | Reference |
|---|---|---|---|
| Width | 8 bits | CRC register and result width | Read guide |
| Poly | 0x1D | Generator polynomial without the leading term | Read guide |
| Init | 0xFD | Initial CRC register value | Read guide |
| RefIn | No | Reflect each input byte before processing | Read guide |
| RefOut | No | Reflect the register before XOR Out | Read guide |
| XorOut | 0x00 | Final value XORed with the CRC register | Read guide |
| Check | 0x7E | CRC of ASCII “123456789” | Read guide |
| Residue | 0x00 | Expected residue after appending a valid CRC | Read guide |
AliasesI-CODE CRC-8
Where CRC-8/I-CODE is used
- 01RFID
- 02I-CODE
- 03Identification systems
CRC-8/I-CODE FAQ
What is the check value for CRC-8/I-CODE?
For the standard ASCII test input 123456789, the check value of CRC-8/I-CODE is 0x7E.
What polynomial does CRC-8/I-CODE use?
CRC-8/I-CODE uses the 8-bit polynomial 0x1D.
Does CRC-8/I-CODE use reflected input and output?
For CRC-8/I-CODE, RefIn is No and RefOut is No.
What is CRC-8/I-CODE commonly confused with?
CRC-8/GSM-A uses the same polynomial (0x1D), which is the usual source of mix-ups — matching the polynomial alone does not reproduce CRC-8/I-CODE. The two models differ in initial value, so a port from one to the other needs those fields checked explicitly, not just the poly.