Cutting VIN power

So, I’m using these sensors that we ordered in from china. They supposedly have standby modes, but… I can’t get that to work no matter what I do.

What I really want to do is just turn off the power to the sensor.

My code currently does this

  • Wait 3 seconds (for sensor to give reliable result)
  • Get value from sensor
  • Send value via network
  • Wait 10 seconds (network can be slow)
  • Deep sleep for 10 minutes.

Right before deep sleep, I want to turn off the sensor’s power. At the start of the code, I want to make sure the sensor has power.

The sensor pulls 5V so is connected to VIN+GND, then the data connections are on RX and TX.

Is there a way for me to do this? If not, does anyone have a suggestion on what circuity I could use to make this happen?

Thanks all!

You could provide some data about these sensors
you could use external circuitry to switch the power for the sensors via a GPIO
you could use 3.3V sensors that draw less than 20mA and supply them via a GPIO

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@ScruffR Hi!

We’re using the Plantower PMS3003 has some technical data

Changing sensors isn’t an option, but using external circuitry is, and so is just figuring out how to do it properly is I guess.


And where have you got PIN3 connected to and how are you controlling that pin?
You’d need to tie PIN3 down to GND via a pull-down resistor to keep the sensor in standby while your device sleeps and pull it high via a GPIO when you want to switch it on.