CFA633-RDI-KU datasheet(71/86 Pages) CRYSTAIFONTZ

71 / 86 page

Crystalfontz America, Inc.

Data Sheet Release Date 2012/02/21

www.crystalfontz.com

CFA633-RDI-KU LCD Module (Hardware v2.0 / Firmware u2v1)

February 2012

Page 71

//Push this byte’s bits through a software

//implementation of a hardware shift & xor.

for(bit_count=0;bit_count<=7;bit_count++)

{

//Shift the CRC accumulator

newCRC>>=1;

//The new MSB of the CRC accumulator comes

//from the LSB of the current data byte.

if(data&0x01)

newCRC|=0x00800000;

//If the low bit of the current CRC accumulator was set

//before the shift, then we need to XOR the accumulator

//with the polynomial (center 16 bits of 0x00840800)

if(newCRC&0x00000080)

newCRC^=0x00840800;

//Shift the data byte to put the next bit of the stream

//into position 0.

data>>=1;

}

//All the data has been done. Do 16 more bits of 0 data.

for(bit_count=0;bit_count<=15;bit_count++)

{

//Shift the CRC accumulator

newCRC>>=1;

//If the low bit of the current CRC accumulator was set

//before the shift we need to XOR the accumulator with

//0x00840800.

if(newCRC&0x00000080)

newCRC^=0x00840800;

}

//Return the center 16 bits, making this CRC match the one’s

//complement that is sent in the packet.

return((~newCRC)>>8);

}

CFA633-RDI-KU Datasheet(PDF) 71 Page - Crystalfontz America, Inc.