CRC check problem

chenbingjy

CRC check problem [Copy link]

I experimented with the CRC16 routine of NXP810 and found that LPC_CRC->WR_DATA_WORD = 0x3534; if (LPC_CRC->SUM != 0xD7D6) { /* §°LED */ while (1) { LPC_GPIO_PORT->PIN0 &= ~LED; /* LED */ myDelay(100); /* ± 100ms */ LPC_GPIO_PORT->PIN0 |= LED; /* ¨LED */ myDelay(100); /* ± 100ms */ } } LPC_GPIO_PORT->PIN0 &= ~LED; /* ¨LED */ I have tried many algorithms, but I cannot find the value of 0XD7D6. Please help me, thank you!

chunyang

First confirm whether the algorithm programming is correct.

zhaojun_xf

It is quite convenient to calculate CRC16 using software, but I have never tried using hardware. Let's see if the method is correct.

chenbingjy

I just don't know how to calculate it.

zhaojun_xf

Are you talking about software or hardware computing?

chenbingjy

The value calculated by the hardware is correct, and I succeeded in the experiment. But I can't calculate the value calculated by the hardware using software. It seems that there is a big-endian mode and a little-endian mode.

chenbingjy

The algorithm found

unsigned int CRC16_IBM(unsigned char *puchMsg, unsigned int usDataLen)
{
unsigned short wCRCin = 0x0000;
unsigned short wCPoly = 0x8005;
unsigned char wChar = 0;

while (usDataLen--)
{
wChar = *(puchMsg++);
InvertUint8(&wChar,&wChar);
wCRCin ^= (wChar << 8);
for(int i = 0;i < 8;i++)
{
if(wCRCin & 0x8000)
wCRCin = (wCRCin << 1) ^ wCPoly;
else
wCRCin = wCRCin << 1;
}
}
InvertUint16(&wCRCin,&wCRCin);
return (wCRCin) ;
}