How is the CRC 16 calculated in the ST25RU3993

[CShac]

I am currently receiving a Tag EPC number and wondering how the CRC -16 value is generated so that I can check on reception. Following an Ack command I Receive 16 bytes in the fifo register which are read out as:

0x30, 0x00, 0xE2, 0x00, 0x42, 0x16, 0xCB, 0x60, 0x60, 0x15, 0x00,0x95, 0x1E, 0xD6, 0xB9, 0x1F.

The Tag EPC number is: 0xE2, 0x00, 0x42, 0x16, 0xCB, 0x60, 0x60, 0x15, 0x00,0x95, 0x1E, 0xD6.

Am I correct to assume the last 2 bytes are the CRC-16, how do we arrive at these numbers?

[After Forever]

1. Go to https://crccalc.com/
2. Paste your data in hex - 3000E2004216CB60601500951ED6
3. Choose Hex
4. Press "Calc CRC-16"
5. Find your B91F in the results

You'll know that it's "CRC-16/GENIBUS" - Polynomial 0x1021, Initial value - 0xFFFF

[CShac]

I did try this website previously, but it seems that I must have mis-entered my data and you are correct it is there.

Many thanks for getting back to my question so quickly.

[After Forever]

Here

#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
 
static const uint16_t crc16_genibus_table[] = {
 0x0000U, 0x1021U, 0x2042U, 0x3063U, 0x4084U, 0x50a5U, 0x60c6U, 0x70e7U,
 0x8108U, 0x9129U, 0xa14aU, 0xb16bU, 0xc18cU, 0xd1adU, 0xe1ceU, 0xf1efU,
 0x1231U, 0x0210U, 0x3273U, 0x2252U, 0x52b5U, 0x4294U, 0x72f7U, 0x62d6U,
 0x9339U, 0x8318U, 0xb37bU, 0xa35aU, 0xd3bdU, 0xc39cU, 0xf3ffU, 0xe3deU,
 0x2462U, 0x3443U, 0x0420U, 0x1401U, 0x64e6U, 0x74c7U, 0x44a4U, 0x5485U,
 0xa56aU, 0xb54bU, 0x8528U, 0x9509U, 0xe5eeU, 0xf5cfU, 0xc5acU, 0xd58dU,
 0x3653U, 0x2672U, 0x1611U, 0x0630U, 0x76d7U, 0x66f6U, 0x5695U, 0x46b4U,
 0xb75bU, 0xa77aU, 0x9719U, 0x8738U, 0xf7dfU, 0xe7feU, 0xd79dU, 0xc7bcU,
 0x48c4U, 0x58e5U, 0x6886U, 0x78a7U, 0x0840U, 0x1861U, 0x2802U, 0x3823U,
 0xc9ccU, 0xd9edU, 0xe98eU, 0xf9afU, 0x8948U, 0x9969U, 0xa90aU, 0xb92bU,
 0x5af5U, 0x4ad4U, 0x7ab7U, 0x6a96U, 0x1a71U, 0x0a50U, 0x3a33U, 0x2a12U,
 0xdbfdU, 0xcbdcU, 0xfbbfU, 0xeb9eU, 0x9b79U, 0x8b58U, 0xbb3bU, 0xab1aU,
 0x6ca6U, 0x7c87U, 0x4ce4U, 0x5cc5U, 0x2c22U, 0x3c03U, 0x0c60U, 0x1c41U,
 0xedaeU, 0xfd8fU, 0xcdecU, 0xddcdU, 0xad2aU, 0xbd0bU, 0x8d68U, 0x9d49U,
 0x7e97U, 0x6eb6U, 0x5ed5U, 0x4ef4U, 0x3e13U, 0x2e32U, 0x1e51U, 0x0e70U,
 0xff9fU, 0xefbeU, 0xdfddU, 0xcffcU, 0xbf1bU, 0xaf3aU, 0x9f59U, 0x8f78U,
 0x9188U, 0x81a9U, 0xb1caU, 0xa1ebU, 0xd10cU, 0xc12dU, 0xf14eU, 0xe16fU,
 0x1080U, 0x00a1U, 0x30c2U, 0x20e3U, 0x5004U, 0x4025U, 0x7046U, 0x6067U,
 0x83b9U, 0x9398U, 0xa3fbU, 0xb3daU, 0xc33dU, 0xd31cU, 0xe37fU, 0xf35eU,
 0x02b1U, 0x1290U, 0x22f3U, 0x32d2U, 0x4235U, 0x5214U, 0x6277U, 0x7256U,
 0xb5eaU, 0xa5cbU, 0x95a8U, 0x8589U, 0xf56eU, 0xe54fU, 0xd52cU, 0xc50dU,
 0x34e2U, 0x24c3U, 0x14a0U, 0x0481U, 0x7466U, 0x6447U, 0x5424U, 0x4405U,
 0xa7dbU, 0xb7faU, 0x8799U, 0x97b8U, 0xe75fU, 0xf77eU, 0xc71dU, 0xd73cU,
 0x26d3U, 0x36f2U, 0x0691U, 0x16b0U, 0x6657U, 0x7676U, 0x4615U, 0x5634U,
 0xd94cU, 0xc96dU, 0xf90eU, 0xe92fU, 0x99c8U, 0x89e9U, 0xb98aU, 0xa9abU,
 0x5844U, 0x4865U, 0x7806U, 0x6827U, 0x18c0U, 0x08e1U, 0x3882U, 0x28a3U,
 0xcb7dU, 0xdb5cU, 0xeb3fU, 0xfb1eU, 0x8bf9U, 0x9bd8U, 0xabbbU, 0xbb9aU,
 0x4a75U, 0x5a54U, 0x6a37U, 0x7a16U, 0x0af1U, 0x1ad0U, 0x2ab3U, 0x3a92U,
 0xfd2eU, 0xed0fU, 0xdd6cU, 0xcd4dU, 0xbdaaU, 0xad8bU, 0x9de8U, 0x8dc9U,
 0x7c26U, 0x6c07U, 0x5c64U, 0x4c45U, 0x3ca2U, 0x2c83U, 0x1ce0U, 0x0cc1U,
 0xef1fU, 0xff3eU, 0xcf5dU, 0xdf7cU, 0xaf9bU, 0xbfbaU, 0x8fd9U, 0x9ff8U,
 0x6e17U, 0x7e36U, 0x4e55U, 0x5e74U, 0x2e93U, 0x3eb2U, 0x0ed1U, 0x1ef0U
};
 
int main()
{
 uint8_t data[] = {
 0x30, 0x00, 0xE2, 0x00, 0x42, 0x16, 0xCB, 0x60,
 0x60, 0x15, 0x00, 0x95, 0x1E, 0xD6, 0xB9, 0x1F
 };
 uint16_t crc;
 uint16_t crc_real;
 uint32_t i;
 const uint32_t data_size = sizeof data - sizeof crc;
 
 crc = ((uint16_t)data[data_size] << 8) | data[data_size + 1];
 
 crc_real = 0xffffU;
 for (i = 0; i < data_size; i++) {
 crc_real = (crc_real << 8) ^ crc16_genibus_table[((crc_real >> 8) ^ data[i])];
 }
 crc_real ^= 0xffffU;
 
 printf("crc = 0x%04x\n", crc);
 printf("crc_real = 0x%04x\n", crc_real);
 
 if (crc_real == crc) {
 printf("OK\n");
 } else {
 printf("ERROR\n");
 }
 
 return 0;
}