NodeMCU Pins D3 and D4

See attached schematic snip (note I’m only showing one relevent sub circuit for clarity - it shows the D3 subcircuit but the other pins have duplicate subcircuits in the same way) - I’m planning to use D3 through D10 as the triggers for MOSFET gates. (D0, D1, and D2 are used for other purposes).

When I was breadboarding I got really weird startup behavior on the nodemcu.

Did some searching around and found this:Using ESP8266 GPIO0/GPIO2/GPIO15 pins

QUESTION 1: So am I right that on D3 and D4 (GPIO 0 and GPIO2), because the MOSFET gate circuit is pulled to ground with a 100K (or 10K, I haven’t decided) resistor, then that’s causing it to boot into a non standard mode?

If so…I think I’ll have to use other I2C pins for what I need since I don’t want to change change the gate circuit.

QUESTION 2: Just out of curiosity, what is the value of the onboard nodemcu resistor that’s pulling the pin up? Anyone know? My understanding is that the on board resistor pulls up the pin, so in order to drive it low, that means the controller will need to connect the pin to ground with less resistance than the inboard resistor, right?

QUESTION 3: For D8 (GPIO15), it’s normally pulled down on startup so probably fine to use?

QUESTION 4: And then for D9 and D10 (GPIO3 and GPIO1) - those are RX and TX…if I’m not planning to use serial monitor, will those cause problems too?

Hmm - I'm also seeing odd behavior with D0 - when I use D0, the onboard LED turns on and the gate seems not to work :(. Is there also oddity with that GPIO and I need to stay away?

Here's a tutorial that explains which GPIO pins you can safely use. Take notes.

What happens if you remove the LED?

Tom.. :slight_smile:

Please, post a picture of the NodeMCU that you own -- there are so many versions of NodeMCU! Are you using wemos LoLin NodeMCU v3?

Thanks folks - here is the NodeMCU I'm using: