Thread: Esp8266 thingy power supply

are you talking about a plug pack that is meant to be a USB device charger, and of what age? When you described your symptom I first suspected that the battery detection in the charger is getting in the road here. I haven't looked in detail at the power output from a "smarter" charger versus an old tech 5v power pack but suspect that you're probably affected by noise. Any way you can smooth it with a cap?

I've been using the nodemcu for quite while now but have never tried to power it from the 5V pin (pin 1). The schematic shows USB 5V connected to pin 1 so it seems like it should work. I've recently switched to the D1 Mini for the smaller form factor but I can dig out a nodemcu tomorrow and give it a try.

in both cases, i used the same plug pack. connecting via the usb port (just power pins) works, and the device boots fine on powerup.
connecting via the Vin pin, it just sits there until i push the reset button.
if i connect an already-powered plug pack, it also boots up fine. I suspect therefore that the issue is the rise time on the power supply, but i dont understand why connecting via usb works and via Vin doesnt. my reading of the circuit is the only difference is a schottky diode to prevent back feeding usb port if vin is being used.
they both feed the onboard 3.3v regulator. so the MCU itself should only see a clean supply.

i didnt actually try a smoothing cap, i guess i could. i also used another plug pack, 9v, as the regulator is specified to 15 volts, but same outcome. hangs until reset button is pressed.

would appreciate if you could try please dmorse.

I just tried it. It boots up with no problem. I added a 10uf capacitor across the pins to slow the rise time a bit (breadboard with several jumpers so enough resistance) and it still works.

It's still setup so let me know if there's anything else you want me to try.

Originally Posted by russ57

.... usb works and via Vin doesnt. my reading of the circuit is the only difference is a schottky diode to prevent back feeding usb port if vin is being used.
they both feed the onboard 3.3v regulator. so the MCU itself should only see a clean supply.
.

As I see the schematic the VCC pin on the USB connector is VDDUSB on the board which is also Pin 1 on the board connector. That is, USB VCC connects directly to Pin 1. No diode between them.

According to
Schematics for ESP-12E DevKit | User Manual for ESP-12E DevKit
There is a schottky diode between Vusb and Vin.
But either way, what ever works on one ought to be fine on the other.

I guess I could try a series diode on the Vin pin.

Actually that would prevent very low voltage being applied to the regulator.
Worth a try I guess.

Ok, sorry, I didn't realize you were using the development kit and not a nodemcu. That schematic is different.

Well, to be honest it's all a bit confusing.
I have read the software is nodemcu and it runs on a Devkit, of which there are apparently 3 versions. The first doesnt fit on a breadboard, and the 3rd is too big for a breadboard. Although I saw some on AliExpress for 5c each (yes, 20 for $1).
I believe I have v2. 0. And I think the circuit is for v2.
20200913_201242.jpg

Keeps me thinking I guess!

just remember that these things are mass produced by the thousands of manufacturers.... there's no actual standard here, no guarantee that you'll get one particular "configuration" from the same manufacturer when you buy in two batches as they'll often make multiple PCBs for different components they have "excess" or were cheap. For example, I have never seen (in the flesh) a nodemcu with that particular IC near the USB, all mine have had tiny QFPs doing that role (I think it's the USB-serial chip)