D1 + base shield v2 + dust sensor



  • hello, i'm a beginner on arduino

    Hardware:
    1.Wemos D1R2 board (https://www.wemos.cc/product/d1.html)
    2.Base shield v2 (http://wiki.seeed.cc/Base_Shield_V2/)
    3.Dust sensor (http://wiki.seeed.cc/Grove-Dust_Sensor/)

    I try to use Wemos D1 and base shield v2 to upload some data from dust sensor.And the Dust sensor need 5V to run it, hence, i choose 5V on base shield V2(it has two options : 3.3V and 5V). However, no matter how many times I try , the monitor screen will appear " ets Jan 8 2013,rst cause:4 boot mode(1,8) wdt reset".

    -> if i try another pin which didn't connect to dust sensor, the board can work.
    -> if i unplug the dust , the board will be normal.
    -> if i try to change the volt on base shield v2 to 3.3v , it will appear the same error message.

    AND
    If i change the dust sensor to MQ-9 sensor on A0(analog pin), the board will stop the power supply immediately.

    Please help me to finish it.



  • Hello @KappaTsemg ,

    please keep in mind that the ESP8266, used on the Wemos D1R2 is a 3.3V device.

    In short you can't use the combination you mentioned !
    The sensor is a 5V device with a 5V digital output. If you connect this to a 3.3V device, the device or at least this input pin can be destroyed. Switching from 5V to 3.3V on the base shield does not help, as the sensor will not work correctly anymore, even the output signal might be in the 3.3V range now.

    What you need is a level shifter or at least a voltage divider.

    Similar is true for the analog input. The maximum input voltage for the A0 is about 3.2V. If you are using a 5V sensor with an analog output that has 0V to 5V output swing, you can damage the device or at least the input pin. Please use an additional resistor of 220k in series.
    7th Dwarf


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