Multiple 1wire Sensors (Ds18b20)



  • In which way I can set the precision for the sensors?

    With 10 sensors in the 1wire no new values are transmitted, I think there is some kind of hick up/problem in the 1wire bus. the EVOK web interface and in node red no new values are displayed/transmitted.

    Is there a way to optimize the 1wire bus?
    10 sensors will need 10* 750ms (12bit precision) to transmit the data, in total 7,5 seconds for all sensors.
    In a evok config file there is set an interval of 3 seconds for the i2c bus. Is this value OK? Is this causing my problems in the bus?
    Or should a new interval set through device definition in the evok.conf under /etc?

    Thanks


  • administrators

    Hello @Christian,
    the precision of the sensors cannot be set via Evok. The only way is to do it by some external tool, e.g.: https://raspberrypi.stackexchange.com/questions/14278/how-to-change-ds18b20-reading-resolution.

    If you cannot read value of any sensor, then it looks more like a HW issue. One faulty sensor can kill whole bus. I would suggest to try one sensor at a time and see if you could read value from all of them.

    The I2C interval isn't affected by the number of sensors or the time they need for the response. The underlying OWFS reads the values sequentially, one sensor at a time.

    Best regards,
    Martin