Translating a project from ESP8266-01 to NodeMCU Amica ESP8266-12E

[gorgon]

Hi,

I'm making a circuit from this recipe. It uses an ESP8266-01 that I would like to replace with a NodeMCU Amica ESP8266-12E. It sends a DMX signal that is isolated with an optocoupler.

The original circuit uses a 470Ω resistor between gpio 2 and the optocoupler - should I remove this? I'm trying to find info on if the gpio 2 pin on the ESP-01 is different from the ESP-12E in terms of resistance but I'm finding it hard to understand.

The original circuit uses two voltage regulators, one for input (5v) and one to convert 5v to 3.3v. Can I skip these and power the circuit from the board, using VIN to power components with 5v and the 3.3v pin to set IC pins to high?

[pylon]

@gorgon

The original circuit uses a 470Ω resistor between gpio 2 and the optocoupler - should I remove this?

No, this the current-limiting resistor you must not eliminate it or your ESP in will be fried.

@gorgon

I'm trying to find info on if the gpio 2 pin on the ESP-01 is different from the ESP-12E in terms of resistance but I'm finding it hard to understand.

Why should there be any difference?

@gorgon

The original circuit uses two voltage regulators, one for input (5v) and one to convert 5v to 3.3v. Can I skip these and power the circuit from the board, using VIN to power components with 5v and the 3.3v pin to set IC pins to high?

If the posted schematics show the original circuit, then the two voltage regulators are for the two parts of the circuit which are isolated by the optocoupler. In a DMX environment I recommend to keep that circuit as it is, removing the isolation is too dangerous.

[gorgon]

@pylon

No, this the current-limiting resistor you must not eliminate it or your ESP in will be fried.

Ok great thanks!
I was asking since I know that there are pull-up resistors associated with pins on different boards.

@pylon

If the posted schematics show the original circuit, then the two voltage regulators are for the two parts of the circuit which are isolated by the optocoupler. In a DMX environment I recommend to keep that circuit as it is, removing the isolation is too dangerous.

So do the voltage regulators also isolate the output part of the circuit (the 75176 ic)? I thought the optocoupler took care of that...

I made a circuit that included the 470 resistor but did power everything through the board, so using the voltage regulator on the board to get 3.3v and using VIN on the board to get 5v, but I haven't gotten it to work. I can get a signal to the board with wifi (i have a led blinking to show activity) but there is no dmx output. Could it be that I have damaged one of the components maybe?

[pylon]

@gorgon

I thought the optocoupler took care of that...

The optocoupler isolates the control signal. If you have the power directly connected you don't have a complete isolation.

@gorgon

I made a circuit that included the 470 resistor but did power everything through the board, so using the voltage regulator on the board to get 3.3v and using VIN on the board to get 5v, but I haven't gotten it to work.

The ESP12E doesn't have a VIN pin. Post a link to the board you're using and schematics of your setup!
Where is the power from?

[gorgon]

@pylon

The optocoupler isolates the control signal. If you have the power directly connected you don't have a complete isolation.

Thank you, I'm learning about the isolation of DCDC converters now and just ordered a handful of 0505S's. This is very useful

@pylon

The ESP12E doesn't have a VIN pin. Post a link to the board you're using and schematics of your setup!
Where is the power from?

I'm using a NodeMCU Amica ESP8266-12E. Not referring to it by its full name is causing confusion here, sorry about that.

The power source is this sony phone charger 5v 1500mA.

Here is a schematic of my setup. I don't know how to use kicad (yet) so I used photoshop. I hope it's readable:

[pylon]

@gorgon

I'm learning about the isolation of DCDC converters now and just ordered a handful of 0505S's.

No every DC/DC converter is isolating! The 0505S is an isolating one though.

@gorgon

I'm using a NodeMCU Amica ESP8266-12E.

That's a NodeMCU, it just based on the ESP12E module. That's about the same as referring to an Arduino UNO as an ATmega328p.

@gorgon

Here is a schematic of my setup. I don't know how to use kicad (yet) so I used photoshop. I hope it's readable:

Yes, that's great.
This should work but the only benefit you have of the optocoupler is the conversion from 3.3V to 5V. The isolation is mostly gone. I would invest into that additional DC/DC converter to get the isolation. It saves the ESP from spikes on the DMX bus but also the DMX devices from the charger output (which is probably even more important).

The original design has a flaw BTW. It constantly drives the DMX bus meaning no other controller will work on that bus, you can only have slaves. I know the standard says that there is only one controller but reality often is different.