DualCam Communication Protocol: Difference between revisions

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 ==CRC-16 calculation==
+CRC is calculated with using 3 input variables:
+. init_value - last packet CRC (or 0 if it's the first packet)<br>
+. poly - binary polynomial expression (0x8408 in our case)<br>
+. data - raw data of the packet (not including the first 4 bytes (cmd ID and packet size) and 2 last bytes (the CRC)
+An example of structure can be found below:
+ function crc16_generic(init_value, poly, data) {
+     let RetVal = init_value;
+     let offset;
+     for (offset = 0; offset < data.length; offset++) {
+         let bit;
+         RetVal ^= data[offset];
+         for (bit = 0; bit < 8; bit++) {
+             let carry = RetVal & 0x01;
+             RetVal >>= 0x01;
+             if (carry) {
+                 RetVal ^= poly;
+             }
+         }
+     }
+     return RetVal;
+ }
 CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. The algorithm how to calculate CRC-16 (also known as CRC-16/IBM) you will find below.