ESP8266 Community Forum

Goal:
Stand alone ESP-01 module and DHT22 sensor fed by usb power.
Module and sensor mounted on protoboard with power supply.
Power Supply - USB fed 5v converted down to 3.3v for above



Gear:
ESP01 Programmer Adapter UART GPIO0 ESP-01 off of eBay. I have two, one modified for programming and one just to use for power/testing.

Fluke87 for meter readings

Mac Pro / iPhone / MBP for coding, testing, and USB connections.

Current Condition:
When ESP is plugged into cheap CH340 programmer board, power reads 3.3v, expected. I am able to program it, remove ground from CHI0 and bring up the WiFi and connect to it.

I move it to my breadboarded power supply. I did my research and while I found many different solutions, this one looked simple and functional for my current needs. I had already done something similar with 12v to 5v earlier. My apologies for the written notes, sometimes I find them quicker in the near term. It seems easy peasy.



I hook up my meter and it reads 3.3v as expected. I also tested the USB feed as I just stripped apart an old cable, and solder header pins on the ends; it read 5v feeding in.

I now connect the ESP-01 module up to the power supply and it drops to 2.6v and I can’t get a connection to it. I may or may not see the SSID. If I do and try to connect to it, I get an error that it can’t connect.

Why the drop of .7 volts when connected to my power supply versus the USB board? Step-up converter? But that doesn’t make sense to me if my supply reads 3.3v when the board is not connected. When I do connect the board I took reading from both the pins on the 01 module and leads coming out of the power rails.

I just placed it back in the USB converter and it powers up AND I can see and connect to the SSID.

Obviously I am not an EE, but want to learn and looking for why or what to check. Any help would be appreciated. I have tried to include all of the data I thought would be relevant.

What is the usb voltage with the ESP connected ? It still should be +5 but could drop due to small size wire in usb cable or just a flaky usb cable with a hiZ connection , are you sure the usb port can deliver 1 Amp
A 0.5 Amp Usb port could also possibly cause this, but I think it will be marginally ok....
You should get yourself a inline USB meter to show V/A , they are resonably priced. Amazon etc.

Put a couple of capacitors in the breadboard at the module. You show that you have 100uF. Connect that as close to the input of the ESP-01 power connections as possible. That might help. I don't consider that the best solution. I would solder an appropriate capacitor directly on your ESP-01. But you can instead solder it to the top of the adapter board. I would use 100uF on your adapter board and then a 0.1uF directly on the ESP-01 but that might not be required, but probably a good idea.

The ESP8266 will draw more than half an amp at startup. And the problem is typically short duration pulse current requirements rather than longer term average requirements. You need to have an adequate power source for the worst case and not the average.

A problem is the use of a linear regulator which will just waste energy and dissipate heat. Get some buck boost converters for your toolbox http://www.ebay.co.uk/itm/LM2596S-ADJ-3 ... SwKtVW0-6u.

Are you powering from a Computer USB port or a mains power charger? You have measured the power and say it drops to 2.6v but which side of the LM1117 is that. If it is the output then what is the input? What is the current being drawn?

David