Some of Stef's Stuff

Discover the ESP8266

by Stefano on 2015.05.17, 5 comments

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First test of the WiFi module based on the ESP8266 chip

Tools baseline

All the tests have been performed with

  • MacBook Pro / OS X 10.10.3
  • Eclipse 4.5 / CDT / Eclipse Arduino Plugin / Arduino 1.5.8 / Java 7 / Python 2.7 (and pySerial 2.7)
  • Arduino Uno board
  • Espressif ESP8266 WiFi module (ESP-01)

Connect to the ESP WiFi interface

Power up the module and connect to the ESP access point.

Ping the default IP address to test the connection.

ESP UART to Arduino

Arduino to ESP-01_bb

MODE: normal operation, with default serial speed 9600

Voltage divider on Arduino TX to drop 5V to 3.3V

MODE: firmware update

Arduino to ESP-01 FW_bb

ESP Transparent Bridge

The ESP can be update to provide transparent operations between its UART and WiFi interface. Every data received on one side is copied to the other without further manipulation and vice-versa.

The firmware is available at ESP8266 Transparent Bridge GitHub page. Clone the repository to modify the firmware yourself or just the binary files to burn to update the ESP.

Update the firmware

To modify the content of the flash memory the pin on the ESP must be LOW (ground)

Once the module is properly connected the esptool is used to flash the firmware.

  • check python, pySerial
  • get esptool (site, file)

To test the “firmware update” mode is enabled request the device MAC address:

To burn the firmware files:


“Failure to connect” error message using esptool.py

Usually the cause of this error is bad cabling of your module and power source (yes, connect all the ground together to provide common reference among different boards). See this issue on the project  page

Also it seems to be caused if a speed is passed a parameter like below:


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5 thoughts on “Discover the ESP8266

  1. Hello Stefan,

    I have Teensy 3.1 running TFT display and Reflow Oven. Thermocouple is writing me Serial data to microSD card – Would it be possible to get Serial print to Computer over ESP8266 WiFi module ?? Teensy 3.1 has 3.6V output which I could use since my operating voltage is 5V DC.
    I am a bit new to this and any explanation would be helpful.


    • Hi Mike,
      you can have the Teensy + ESP to serve a webpage you can access from the PC (refer to PRJC forum).
      You probably want to power the ESP with an external 3.3V (see AMS1117 and equivalents) as the Teensy’s top at 100mA draws more than that (see typical power consumption)
      Make sure to have the voltage divider between Teensy TX and ESP RX if your output logic level is 5V as the ESP8266 level is 3.3V.


  2. Hello Stef.

    I have an Uno r3. i have a CC3000 wifi shield and an esp8266.

    Currently no matter what we have tried both our technician and myself cannot for the life of us simply connect them.

    every time we’re met with;

    Connecting to wifi…

    No Response from Wifi moduleor wifi module not present.

    Both were purchased from separate sellers and the uno r3 works just fine. we have both tried all the usual set ups… the shield should have been the simple enough.. but to no avail.
    we are using an external power source.

    only the red light on the esp is on. if all GP0*’s are connected to 3.3v we can get a single flash from the blue light. but still the same no module remains.

    Please help as we’ve been working on this for almost 3 weeks now and we’re at a total and utter loss for what would have been an extremely easy test.

    Thank you in advance.


    • Hi Joe,
      it’s a basic test and maybe you’ve tried already but can you see the ESP access point on your mobile phone?


  3. Hi ,I would like to make my two ESP’s to communicate using my homewifi network. I have two MCU’s with UART’s at 9600 8 N 1 connected to ESP_A and ESP_B respectively.
    I just want to replicate the ESP_A UART input to the ESP_B output and viceversa.
    How could I do that ?
    I will appreciate to read from you at iw2fvo@yahoo.com for me to have a quicker look.
    Thanks in advance for any help.

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