- 16 -

processing;

7. The communication message frame after all the bytes calculated according to the above

steps completed, the high and low byte of the resulting 16-bit CRC register exchange;

8. The resulting CRC register contents is: CRC code.

◎CRC calculation code in C language code

Description: This program to calculate the length len * ptr bytes before the CRC.

unsigned short crc16(unsigned char *ptr, unsigned char len)

{

unsigned short crc =0xFFFF;

unsigned char i;

while(len--)

{

crc ^=*ptr++;

or(i=0;i<8;i++)

{

if(crc & 0x01)

{

crc>>=1;

crc^=0xA001;

}else

{

crc>>=1;

}

}

}

return crc;

}

8.2.4

I C Communication Timing

AM2321 sensor I C communication, although according to the standard I C communication

sequence, but must follow our communication protocols and communication timing requirements, in

order to accurately read the sensor. In strict accordance with the communication protocol and timing,

please read the design.

◎I C Read full Timing Example

Figure 14 shows the read sensor when the full sample and write a special time requirements, in

strict accordance with the requirements of the special time to read and write, otherwise it will appear

unreadable sensors or incorrect data and so on. Several timing diagram special needs attention, the

time requirements detailed in Figure; host communication from beginning to end, for a maximum of

3S.

2

2

2

2

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Enterprise QQ: 4006305378

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