DS18B20 @ Grove Connector

  • I connected an DS18B20 w/ pullup to the Grove connector and want to readout temperature. No success.
    Connecting it to the header GND, VCC and G26 it works as expected.
    I tried G32 and G33 at Grove w/o success.
    What's wrong there?

  • I would like to do temperature measurements with 6 x DS18B20 connected to an M5Stack-FIRE.
    I am little confused by the work and description of ckuehnel and would like to ask the following questions.

    Do I understand it correct:

    • It works fine, if all 6 sensors are connected "in parallel" to the GROVE-PORT B (GND=black, 5V=red, G26=yellow) plus the 4,7kohm resistor?

    • There is NO need to access any I/O-pins via the M-bus-connector?

    0_1559840519810_GROVE-Connector FIRE s.jpg

  • Additional questions regarding connecting temperature sensor DS18B20 to M5Stack-FIRE:

    What is the maximum possible cable-length of a DS18B20 temperature sensor connected to a M5Stack-FIre if:

    • a) only one single Sensor is connected?
    • b) 6 sensors are connected?

  • @grelm Does DS18B20 have a unique address to identify the 6 sensors if they don't have an address, or they share the same address you can not expect reading correct data from them, they will have conflicts by wiring them all to one G26 pin.

  • If I recall correctly, they should have been given individual different numbers in the factory.
    Wire length is unknown but for unshielded cables I would recommend keeping them very short for data. If you are getting issues, you may need to look at making some shielded cables.
    Does Changing cable lengths result different readings?
    You may also need an additional power supply to the device.

  • Adress-Issue: Extract from data sheet:
    Each DS18B20 has a unique 64-bit serial code, which
    allows multiple DS18B20s to function on the same 1-Wire
    bus. Thus, it is simple to use one microprocessor to
    control many DS18B20s distributed over a large area.

    So I think, I can really run 6 Sensors on ONE GOVE-Port (B)!

    Power Supply:
    According to data sheet, a single DS18B20 draws 1,5 mA max. during conversion.
    In addition to that there is the current thru the necessary 4,7 kOhm resistor = 1 mA.
    In total there will be abut 10 mA (incl. some reserve) needed from the 5V-pin of the GROVE.port.
    How high is the maximum recomended current which a GROVE-Port can deliver?

    I think, I will have to do some testing.
    As soon as I am done with it, I am going to post the results on that in this forum.

  • @grelm I think (but i could be wrong) 10mA should be ok.