Pull down resistor output pin
Posted:
Mon Dec 19, 2016 1:24 pmby stern0m1
I want to use an outpin to close a switch of a circuit thats cut by ground.
Does it make sense to connect the pin to ground with a resistor like a pulldown resistor on an input pin?
Thanks
Re: Pull down resistor output pin
Posted:
Mon Dec 19, 2016 2:00 pmby martinayotte
Your question is pretty vague.
What is the other device connected to that output ?
Maybe you should provide a schematic ...
Re: Pull down resistor output pin
Posted:
Mon Dec 19, 2016 2:10 pmby stern0m1
My question is the general concept to use an output pin as a switch for another circuit without a relay.
If the other circuit needs a connection to ground to complete the circuit.
The other circuits ground and the esp8266 ground are connected.
Thanks
Re: Pull down resistor output pin
Posted:
Mon Dec 19, 2016 2:21 pmby martinayotte
I don't want to give any wrong advices, especially that scenarios can be totally different depending of the other device.
Yes, a GPIO can provide ground to another device, but when this GPIO turned off it ground, it is providing HIGH, therefore 3.3V. How the other device will react with such voltage.
Also, how much current the other device will sink to the ground, maybe GPIO can't provide a ground strong enough.
So, it is maybe better to use a MOSFET here in parallel with the switch you described, and having the GPIO controlling this MOSFET, where HIGH on its gate will turn it on, this MOSFET can then providing strong ground of several amperes if required.