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ESP8266 failed to connect without pc

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DF Electronics
New Member
Joined: 1 year ago
Posts: 2
Topic starter  

Hello to everyone,

I'm quite new to ESP family, although i have follow the instructions in order to implement DHT22 sensor & switch for the Arduino IoT platform.

The  project works even if i add some parameters to monitoring my alarm system on the dashboard.


The problem is that project works only when is hooked up to my pc. When i disconnected from my pc and power it up from a cellular charger, ESP8266 can't connect to the wifi router. 


What i have done wrong?



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DroneBot Workshop
Noble Member Admin
Joined: 4 years ago
Posts: 1170

@df-electronics  It may be that the charger you are using to power the ESP8266 does not have enough current, and your ESP8266 is experiencing a "brownout" condition.  The radio in these devices needs a big burst of current when initially connecting to your wifi network.

Try using a USB supply or power bank that has a greater current capability and see if it resolves the issue.



"Never trust a computer you can’t throw out a window." — Steve Wozniak

Prominent Member
Joined: 2 years ago
Posts: 784

Hi @df-electronics,

  Bill's advice is undoubtedly sound, so try that first.


If you are still stuck, what follows depends on whether you program can use the Arduino serial monitor when you are connected to your PC to provide some useful status and diagnostics. If so, maybe you could try a 'mid-way' configuration in which your ESP is powered by the charger, but the serial monitor TX/RX and associated return is still connected to your PC to indicate what it is doing.

However, note that you before you try this suggestion, you must ensure there is no chance of power being fed back to your PC. That is your 'cellular charger' voltage output should 3.3V or 5V (chosen to match the connection to the ESP board), and electrically isolated from your house mains power, including the earth return. A 'cellular charger' of the common wall plug type, with a USB plug to charge a mobile phone, will usually meet this requirement.

The last paragraph may look a little paranoid, but there have been cases of people writing off their laptop by plugging faulty equipment into the USB socket of the PC. The 5V USB power line is often shared with many chips on the laptop's motherboard that will rapidly expire if the voltage exceeds 5V.

Good luck with your project.

DF Electronics
New Member
Joined: 1 year ago
Posts: 2
Topic starter  

Thank you both very much for the help.


I found the problem. By mistake i had used D3 pin for a contact monitoring. That pin when is pulled low boot fails. 


Many thanks both of you again