ESP8266 Community Forum

- Sat Aug 01, 2015 12:18 pm #24769 I'm pretty new to electronics in general, but I've been doing a lot of research and trying to determine the best way to safely and reliably connect an ESP-01 to an Arduino Uno.

I understand that the Rx pin is only 3.3v and the Arduino outputs 5v on the Tx pin, so I am using a CD4050 or 74HC4050 to do the level translation.

This is the diagram as it stands now:



Now, I read during my initial research (though I cannot find that page again now that I'm looking for it) that the 3.3v out on the Arduino Uno may not be reliable enough to supply enough power to the ESP-01 and that the 5v downshifted to 3.3v should be used. Is that true? And if so, how would I go about wiring that up?

Thanks so much for your help!
Tasoril

- Sat Aug 01, 2015 3:36 pm #24781 If you run the ESP from a Uno how much power can it supply is the question . Whether 5 or 3.3 V the ESP needs at least 250 mA all the time available at 3.3V so how much can the regulator reliably provide?

Also I'm curious what the RX/TX are doing on digital pins? What are you planning to run that requires power.

Get you modules here:

https://www.banggood.com/custlink/KvGGhGF4wG

- Sat Aug 01, 2015 5:15 pm #24787

If you run the ESP from a Uno how much power can it supply is the question . Whether 5 or 3.3 V the ESP needs at least 250 mA all the time available at 3.3V so how much can the regulator reliably provide?

Also I'm curious what the RX/TX are doing on digital pins? What are you planning to run that requires power.

The RX/TX are connected based on documents I found online for the hookup. Should they be hooked to pin 1/0 for RX/TX respectively instead?

As for 250mA, is that something that the Arduino Uno is incapable of? The only other item that is to be hooked up are 2x 5v relays. Ultimately the end design will be a custom PCB rather than an Arduino hooked to both devices, but I was under the impression that the Arduino would be able to supply ample power to those two items. If not, I'll need to add a breadboard power supply for the testing phase in order to power it properly.

Edit: Updated image below.



Edit 2: Based on the documentation from the main Arduino page, the 3.3v pin can only supply ~40mA of power. The page doesn't indicate how much power the 5v pin can supply. I assume that the remaining power after the power required by the Arduino itself will be passed through the 5v pin. Is this correct? If so, supplying the Arduino with 1A of power via USB, and assuming the Arduino itself only uses ~50mA of power to operate, that should leave me with ~950mA to work with for operating sensors and modules attached to the Arduino's 5v pin, which is more than enough to operate everything I need to operate. Am I understanding that correctly? If so - I need to pass the 5v pin through the CD4050/74HC4050 and then on to the power inputs on the ESP-01 to ensure ample power is provided to it. Correct?

Edit 3: Updated images.

Would I still need to use the 3v3 to the Vcc of the 74HC4050 like so?


Or is using the 5v fine on the 74HC4050, like so?


I see in the spec sheet that the 74HC4050 takes between 2v and 6v on the Vcc line, but I don't understand if the Vcc contributes to the output voltage on the A lines, or if that's solely based on the input voltage on the Y lines.

- Sun Aug 02, 2015 1:49 am #24804 When you play with these things its expected that you will do the research yourself not keep asking others to do it for you . That's the fun , research it , think it through a,build it and then you get the satisfaction of doing it yourself when it works.

The reference you put up says
DC Current per I/O Pin 40 mA
DC Current for 3.3V Pin 50 mA

The 5 V will only get what the computer puts out for that particular board . Probably 250 to 500 mA , I don't remember. So you can try it and see but if its erratic suspect the power supply first

Yu need to research the RX/TX lines .. I thought I saw they were not crossed but that was for programming another arduino chip. You might have to cross them for what you want.

Get you modules here:

https://www.banggood.com/custlink/KvGGhGF4wG