crc8.ino

// works at {"t":22.3}148# - 65, like espruino
uint8_t input[20];
String  inputString = "";           
boolean stringComplete = false;  
boolean startInput = false;
uint8_t next;
uint8_t total;

// static const uint8_t PROGMEM crc_table[] = {
static const uint8_t crc_table[] = {  
    0x00,0x5e,0xbc,0xE2,0x61,0x3F,0xDD,0x83,
    0xC2,0x9C,0x7E,0x20,0xA3,0xFD,0x1F,0x41,
    0x9D,0xC3,0x21,0x7F,0xFC,0xA2,0x40,0x1E,
    0x5F,0x01,0xE3,0xBD,0x3E,0x60,0x82,0xDC,
    0x23,0x7D,0x9F,0xC1,0x42,0x1C,0xFE,0xA0,
    0xE1,0xBF,0x5D,0x03,0x80,0xDE,0x3C,0x62,
    0xBE,0xE0,0x02,0x5C,0xDF,0x81,0x63,0x3D,
    0x7C,0x22,0xC0,0x9E,0x1D,0x43,0xA1,0xFF,
    0x46,0x18,0xFA,0xA4,0x27,0x79,0x9B,0xC5,
    0x84,0xDA,0x38,0x66,0xE5,0xBB,0x59,0x07,
    0xDB,0x85,0x67,0x39,0xBA,0xE4,0x06,0x58,
    0x19,0x47,0xA5,0xFB,0x78,0x26,0xC4,0x9A,
    0x65,0x3B,0xD9,0x87,0x04,0x5A,0xB8,0xE6,
    0xA7,0xF9,0x1B,0x45,0xC6,0x98,0x7A,0x24,
    0xF8,0xA6,0x44,0x1A,0x99,0xC7,0x25,0x7B,
    0x3A,0x64,0x86,0xD8,0x5B,0x05,0xE7,0xB9,
    0x8C,0xD2,0x30,0x6E,0xED,0xB3,0x51,0x0F,
    0x4E,0x10,0xF2,0xAC,0x2F,0x71,0x93,0xCD,
    0x11,0x4F,0xAD,0xF3,0x70,0x2E,0xCC,0x92,
    0xD3,0x8D,0x6F,0x31,0xB2,0xEC,0x0E,0x50,
    0xAF,0xF1,0x13,0x4D,0xCE,0x90,0x72,0x2C,
    0x6D,0x33,0xD1,0x8F,0x0C,0x52,0xB0,0xEE,
    0x32,0x6C,0x8E,0xD0,0x53,0x0D,0xEF,0xB1,
    0xF0,0xAE,0x4C,0x12,0x91,0xCF,0x2D,0x73,
    0xCA,0x94,0x76,0x28,0xAB,0xF5,0x17,0x49,
    0x08,0x56,0xB4,0xEA,0x69,0x37,0xD5,0x8B,
    0x57,0x09,0xEB,0xB5,0x36,0x68,0x8A,0xD4,
    0x95,0xCB,0x29,0x77,0xF4,0xAA,0x48,0x16,
    0xE9,0xB7,0x55,0x0B,0x88,0xD6,0x34,0x6A,
    0x2B,0x75,0x97,0xC9,0x4A,0x14,0xF6,0xA8,
    0x74,0x2A,0xC8,0x96,0x15,0x4B,0xA9,0xF7,
    0xB6,0xE8,0x0A,0x54,0xD7,0x89,0x6B,0x35
};

uint8_t crc8(uint8_t *addr, uint8_t len){
  uint8_t crc = 0;
  while(len--){
     crc = crc_table[*addr++ ^ crc]; 
  }
 return crc;
}


void setup() {
  Serial.begin(9600);
 }

void loop() {
  if (stringComplete) {
    uint8_t a = crc8(input, total);
    Serial.print("crc8 at ");
    Serial.print(inputString);
    Serial.print("is ");
    Serial.println(a);
    stringComplete = false;
  }
}

void serialEvent() {
  while (Serial.available()) {
    char inChar = (char)Serial.read();
    if((inChar == '{')&&(startInput == false)){
      startInput = true;
    }
    if(startInput){
      input[next] = inChar;
      inputString += inChar;
      next++;
      if (inChar == '\n') {
        total = next - 1;
        stringComplete = true;
        next = 0;
        startInput = false;
      }
      if(next > 19) {
        next = 0;
        startInput = false;
      }
    }  
  }
}