【提问】What is a checksum? Is it very important? I had a painful experie...

cemal

I save some important data in the eprom of my dwin screen. however, he sometimes reads incorrectly while reading. my device has worked for two months. every day he read correctly from the eprom of the screen. Two months later he read wrong once. so I had problems with my customers. but I guess this error is because of me. what could be the reason for this? I read a statement about the checksum in a document, but I did not pay any attention to it. I did not use checksum in communication. Could this be the cause of my problem?
my screen modal: DMT80600L104_01WT

306118439

YOU need to do CRC verify

ANSI CRC-16(X16+X15+X2+1）format was adopted in DGUS and program C as follows:
unsigned char CRCTABH[256]={0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0
0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41
0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0
0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1
0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1
0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0
0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40
0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1
0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0
0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40
0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0
0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0
0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41
0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0
0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41
0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0
0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40
0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1
0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0
0x80,0x41,0x00,0xC1,0x81,0x40};
unsigned char CRCTABL[256]={0x00,0xC0,0xC1,0x01,0xC3,0x03,0x02,0xC2,0xC6,0x06
0x07,0xC7,0x05,0xC5,0xC4,0x04,0xCC,0x0C,0x0D,0xCD
0x0F,0xCF,0xCE,0x0E,0x0A,0xCA,0xCB,0x0B,0xC9,0x09
0x08,0xC8,0xD8,0x18,0x19,0xD9,0x1B,0xDB,0xDA,0x1A
0x1E,0xDE,0xDF,0x1F,0xDD,0x1D,0x1C,0xDC,0x14,0xD4
0xD5,0x15,0xD7,0x17,0x16,0xD6,0xD2,0x12,0x13,0xD3
0x11,0xD1,0xD0,0x10,0xF0,0x30,0x31,0xF1,0x33,0xF3
0xF2,0x32,0x36,0xF6,0xF7,0x37,0xF5,0x35,0x34,0xF4
0x3C,0xFC,0xFD,0x3D,0xFF,0x3F,0x3E,0xFE,0xFA,0x3A
0x3B,0xFB,0x39,0xF9,0xF8,0x38,0x28,0xE8,0xE9,0x29
0xEB,0x2B,0x2A,0xEA,0xEE,0x2E,0x2F,0xEF,0x2D,0xED
0xEC,0x2C,0xE4,0x24,0x25,0xE5,0x27,0xE7,0xE6

cemal

what exactly do these mean? how do i apply it in my software?

Hayley

Hi Sir, CRC is a check code, which can be added or not after each instruction. To judge whether this instruction is normal, it cannot be sent if it is wrong. If you have set the check code, then the command may be wrong, and maybe it was not sent successfully. But if you haven't set it before, I think maybe there are some other questions.

cemal

I've never used crc before. I use the following command while writing to the memory of the dgus screen. but sometimes I get wrong data.



I just learned what CRC does. but I don't know how to use it. What does CRCTABH/L [256] mean? what am i going to do with it?

ZJB19921204

Hello, CRC is a channel coding technology that generates short fixed bit parity check codes based on network data packets or computer files. Our screen CRC needs to enable verification in the configuration file. The model you are using does not have CRC enabled

cemal

Do you mean that the model I use does not have CRC feature?
So how can I avoid erroars in reading data from the screen's memory?

ZJB19921204

Yes, the instruction set does not have CRC. If you need CRC function, you need to change the configuration screen

cemal

well, How can I change the configuration screen

cemal

How can I change the configuration screen