WiFi issue when i power Wemos D1 Mini via 5v pin

I have an Wemos D1 Mini board and when i upload the code to my board and run the unit from my computers USB, all works fine. The code works, and WiFi connects within few seconds.

But when i attach the board to an PCB to soldered connectors where the board gets power via LM7805 and inn to 5v pin i can see the LED indicator on the board lights up, but the code never runs and wifi does not work.

Sometimes when i just take out the Wemos from the PCB and reconnect it without turn of the power to the PCB it worsk fine. But not always. When i unplug the power to the PCB with Wemos in the slots i never gets the board to work. It lights up and the led indicator lights, but no code is running and no wifi.

I have made several boards like this and i have never had issuses before.

The PCB the Wemos is connectet to is powered with a brand new 9v 2amp power supply. On the PCB i have an LM7805 that regulate the volt to 5v and a 470uF capasitor before the board. Nothing else.

To the right inside the box i have made an identical unit an that unit works perfectly and it has never lost the wifi the last 60 days. I can also reconnect the power without any problem and the wifi reconnects etc.


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But this time, i just not get it to work with external power. With USB connectet, all works fine.

What supplys voltage to the 5v pin? When my WeMOS board is powered via the USB connection, the VIN pin reads something like 4.9v (the USB voltage) and the 5v pin reads something like 5.1v. It gave me the notion that the voltage for the 5v pin was generated by the board and not directly from the USB supply. Try powering the board via the VIN pin.

zoomkat:
What supplys voltage to the 5v pin? When my WeMOS board is powered via the USB connection, the VIN pin reads something like 4.9v (the USB voltage) and the 5v pin reads something like 5.1v. It gave me the notion that the voltage for the 5v pin was generated by the board and not directly from the USB supply.

I power 5v pin with 5v from LM7805 and my supply is an 9v 2a supply. The same way i powered my other board on the picture that works fine.

I have also tried other Wemos D1 Mini boards (i have 10 of them) and noeone will run the code or connect to Wifi when powered externaly.

With USB powered throw the USB intake, all works fine. But not if i power the board via 5v pin with 5v from an LM7805.

"With USB powered throw the USB intake, all works fine. But not if i power the board via 5v pin with 5v from an LM7805."

To get to the point, the board may only receive operating power from VIN or thru a 3.3v pin (the board operating voltage). The only function of the 5v pin may be is to power 5v powered attached components like sensors and such. If you can find a schematic of the board, that probably could explain things.

No, i have powered my other boards the same way. The 5v pin can be powered to give power to the board. i have done that with my other boards.

I just don't know why i can't get it to work with external power this time...

Same voltage in to the same 5v pin powered throw LM7805 and a 470uF capasitor as my other boards. But this time i just can't get it to work properly with external power.

"as my other boards"

Your "other boards" may be "different", but it is what it is. Good luck.

An ESP8266 working on 2.4Ghz and an ESP32 working on 2.4Ghz.
Does that work?, and what’s the point of that.
Leo…

@zoomkat

All my total of 13x boards is from same dealer. All of them has worked perfectly, but this time i’m stucked.

Off course i may have did something wrong, but i can’t see what...

OK, here is the schematic of the WeMOS D1 Mini.
[

Expand<](https://escapequotes.net/wp-content/uploads/2016/02/wemos-d1-mini-shematics.jpg)
zoomkat, there is no “Vin” pin. The “5V” pin is fed by a diode from the USB 5 V and is the source for the 3.3 V on-board regulator. Apart from not losing the voltage from the diode, there is no difference between powering from the “5V” pin than from the USB.

I see no 7805 in the illustration at the top. There is a switchmode regulator board.

What happens when you actuate the reset button on the D1 Mini?

Obviously you have checked the output voltage of that regulator that you are feeding to the “5V” pin. :roll_eyes: It is sounding like a problem with the start-up of the regulator.

Paul__B:
OK, here is the schematic of the WeMOS D1 Mini.
[

Expand<](https://escapequotes.net/wp-content/uploads/2016/02/wemos-d1-mini-shematics.jpg)
zoomkat, there is no “Vin” pin. The “5V” pin is fed by a diode from the USB 5 V and is the source for the 3.3 V on-board regulator. Apart from not losing the voltage from the diode, there is no difference between powering from the “5V” pin than from the USB.

I see no 7805 in the illustration at the top. There is a switchmode regulator board.

What happens when you actuate the reset button on the D1 Mini?

Obviously you have checked the output voltage of that regulator that you are feeding to the “5V” pin. :roll_eyes: It is sounding like a problem with the start-up of the regulator.

Oh my god!!.. Your’e absolutelig right!

It’s no 7805 regulator on my other board!

So if i power the Wemos D1 Mini with 9v to the 5v pin it would work? (My other board beeing powered with 9v from LM2595 regulator).

When i press reset button nothing happens.

I’m really sorry. Now i’m just feeling stupid…

Bjerknez:
So if i power the Wemos D1 Mini with 9v to the 5v pin it would work?

If the WeMOS indeed has the specified RT9013, then powering it from 9 V is a very bad idea indeed! :astonished:

If you have a proper 5 V supply, fed to the 5 V pin, then using reset should start it up correctly.

Paul__B:
If the WeMOS indeed has the specified RT9013, then powering it from 9 V is a very bad idea indeed! :astonished:

If you have a proper 5 V supply, fed to the 5 V pin, then using reset should start it up correctly.

Ok, then i still have a problem...

The 5v pin gets 5v from LM7805 and is beeing powered with an 9v 2a supply thats brand new...

Need to measure it under all circumstances.

"zoomkat, there is no "Vin" pin. The "5V" pin is fed by a diode from the USB 5 V and is the source for the 3.3 V on-board regulator. Apart from not losing the voltage from the diode, there is no difference between powering from the "5V" pin than from the USB.

I see no 7805 in the illustration at the top. There is a switchmode regulator board."

Well, this is a picture of the WeMOS boards I have. I see a VIN pin, but YMMV. If the board uses a switching voltage regulator, then it may be able to produce 5.1v from the 4.9v USV power source in my case. If the 5v pin is supplied from the output of a switching regulator, then are you saying the board can be powered by back feeding thru the switching regulator? What voltages do you measure on your WeMOS board?

Suggest you read - carefully - the very first line of the OP (as well as the subject line) and look at the picture. :roll_eyes:

Still the question why there is a WeMos D1 mini in that box.

Can't the ESP32 do everything?
Leo..

"Suggest you read - carefully - the very first line of the OP (as well as the subject line) and look at the picture."

I'm using my experience with my WeMOS board, which appears to have a pin connected to line voltage to the board. I'll be watching for your solution to the OP's issue. :wink:

I think Paul__B is trying to say that a "D1" and a "D1 mini" are two different boards.
The only thing they have in common is the ESP8266 module.
Leo..

"I think Paul__B is trying to say that a "D1" and a "D1 mini" are two different boards.
The only thing they have in common is the ESP8266 module."

As the boards are made by the same company for the same chip, I would suspect the boards have some similar/common design features. I've just posted up what I see with my development board. Maybe those with the mini boards can post up what they see with their boards.

Wawa:
I think Paul__B is trying to say that a "D1" and a "D1 mini" are two different boards.
The only thing they have in common is the ESP8266 module.

Well, I wasn't "trying"; I was pointing out what should be blunderingly obvious!

zoomkat:
As the boards are made by the same company for the same chip, I would suspect the boards have some similar/common design features.

Indeed they do. Yes, they both have an ESP8266 module.

And they both have the same USB chip (I think) and reset/ programming circuitry. And they both have a RT9013 regulating 5 V to 3.3 V.

However nothing else is similar. The WeMOS D1 - which curiously cannot be found on the wemos.cc website - is a sort of curious emulation of the Duemilanove (like many clones, it does not resemble a UNO) with a 5 V converter which can actually power other 5 V devices with active power switching and a buffer on the D13 (GPIO14) LED.
Schematic (obfuscated)