Convert DS18B20 temperature to string


  • Banned

    I want to convert DS18B20( [link removed by moderator]: )
    temperature (4-bytes code from datasheet) to string with accuracy 0.1°C (like sprintf %.1f). AVR. C language (avr-gcc). I need for small code, so sprintf, floating-point types and round from math.h is bad idea. My following current code is bad also:

    void reverse_string(char *s)
    {
    char *p, c;

    for (p = s + strlen(s) - 1; s <= p; ++s, --p) {
        c = *p;
        *p = *s;
        *s = c;
    }
    

    }

    void ts_to_string(uint16_t ts, char *s)
    {
    int8_t n = (int8_t)(ts >> 4);
    uint8_t neg = n & 0x80;
    char *p = s;
    float f;

    if (neg)
        n = -n-1;
    do {
        *p++ = n % 10 + '0';
    } while ((n /= 10) > 0);
    
    if (neg)
        *p++ = '-';
    
    *p = '\0';
    reverse_string(s);
    *p++ = '.';
    
    f = (float)(ts & 0xf) / 16.0;
    if (neg)
        f = 1.0-f;
    *p++ = (char)round(f * 10.0) + '0';
    *p = '\0';

  • Mod

    Accound banned for spam. Promotes a vendor and has copied a question from https://electronics.stackexchange.com/questions/33103/convert-ds18b20-temperature-to-string


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