Introduction: $1 USB to UART-serial Flashing Device (dongle) With 3.3 V Power Supply for ESP8266MOD ESP-12 Module

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Sometimes you just need a handy device that you can use to program your ESP8266MOD ESP-12 module. Typically, you would put your ESP8266MOD ESP-12 module on a breadboard and wire the USB to UART on to it. Most uploads fail because of insufficient power that is supplied by the USB to UART device. That necessitates the use of an external power source typically 5V with a 3.3 V converter.

But there is a solution, and the solution does not involve a $15 FTDI, all it takes is a CH340 USB to UART device with a payload of a 3.3V power regulator.

In this instructable I will demonstrate the construction of a self-contained dongle that has enough power at 3.3V, with enough output wires to flash your ESP8266MOD ESP-12 module without the need of a breadboard.

If you are getting the following error, then you want to build this:

warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_sync failed error:
espcomm_open failed error:
espcomm_upload_mem failed error:
espcomm_upload_mem failed

Step 1: Things Needed

USB to TTL converter UART module CH340G CH340 3.3V 5V switch ($0.65)

AMS1117 5V to 3.3V DC-DC Step down Power Supply ($0.22)

Piece of shrink wrap or electrical tape.

Piece of plastic sheet – thickness of a credit card.

Step 2: Preparing the AMS1117 5V to 3.3V DC-DC Step Down Power Supply

Start of by breaking the plastic at the bottom of the input pins and slide the pieces out. Then heat the pins one pin at a time with a soldering Iron and slide them to the back side of the board and solder them back. Then bend the pins as shown in the picture. Clip them to align with the +ve and -ve pins on the USB to TTL converter UART module

Step 3: Preparing the USB to TTL Converter UART Module

Cut and remove the transparent shrink wrap. Cut it from the side to prevent cutting connections on the PCB. I learned it the hard way.

Reheat and prepare the +ve and -ve pins on the USB to TTL converter UART module.

If the six output and jumpers pins are sticking out excessively from the surface then clip them with a wire cutter or file them down. If you file them down then be sure to clean off the filings from the surface.

Step 4: Putting It Together

Solder the positives and negatives of the power supply and the USB to TTL converter UART module together. Cut the plastic as shown and insert it in between to prevent shorting.

Shrink wrap or put a tape over it. Be sure to set the jumper to 3.3V.

Step 5: Connecting to ESP8266MOD ESP-12

The +ve and -ve from the 3.3V power supply pins go to the +ve and -ve on the ESP8266MOD ESP-12.

Additionally connect:

Rx on USB to UART -> Tx on ESP8266MOD

Tx on USB to UART -> Rx on ESP8266MOD

Ground on USB to UART -> GPIO0 on ESP8266MOD

It is ready to flash.

Step 6: Settings on the Arduino IDE

This image provides the settings I used to flash the ESP8266MOD ESP-12 module. Your COM port could be different. Be sure to manage that.and change it to what you discover. Be sure to remove the -ve from GPIO0 and restart the ESP8266MOD ESP-12 after flashing is complete.