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The files contained in this repository are intended to be ran on a Tessel 2. Their purpose is to demonstrate an HTTP server and API. A browser is used to view an HTML file which contains buttons that will cause the green or blue LEDs to toggle their state.


This project code is modified from the some of the same files found at -


  • index.js -

    • Added ability to use POST rather than GET to toggle the LEDs.
    • Added _toggleLED() to toggle the LED for POST requests.
    • Kept the ability to use GET (for demonstration) to toggle the LEDs.
    • Renamed some function arguments: request to req and response to res.
    • Removed the arg url from showIndex(), it was unused.
    • Added calls to console.log() to output additional run-time info.
    • Added comments.
    • Removed the unused req arg in the following -
      • showFavicon(req, res) to showFavicon(res)
      • showIndex(req, res) to showIndex(res)
      • toggleLED(url, req, res) to toggleLED(url, res)
  • index.html -

    • In toggleLED() changed method to POST from GET.
    • Removed the call to req.send(null), it was causing DOM errors. (might not be required for POST)


You will require the following -

  • A PC/Mac with NodeJS installed.
  • A Tessel 2 configured and working with Tessel example code(i.e. "Blinky").
  • Your favorite code editor.
  • Somewhere comfortable to sit & work.


All the necessary files are within this repo. You should copy them into a convenient folder and then open a command line in that folder.

Next you will need the IP address of your Tessel board. This will give you that information -

t2 wifi

You should see something like this -

INFO Looking for your Tessel...
INFO Connected to Tessel-02A30CB079FF.
INFO Connected to "YOUR_SSID"
INFO IP Address:
INFO Signal Strength: (70/70)
INFO Bitrate: 54mbps

Copy the IP address, you'll need it for the browser.

Now you can run this command and start the application -

t2 run index.js

You should see output similar to the following -

INFO Looking for your Tessel...
INFO Connected to Tessel-02A30CB079FF.
INFO Building project.
INFO Writing project to RAM on Tessel-02A30CB079FF (9.216 kB)...
INFO Deployed.
INFO Running index.js...

Next open a browser and point it at http://<your-tessel-ip-address>:8080.

Index Page

And at the same time you should see similar output from the Tessel -

method = GET
path = /
method = GET
path = /favicon.ico

Now click one of the buttons and the corresponding LED will turn on(or off) and its status change will be displayed in the browser.

Index Page Green LED On

And at the same time you should see similar output from the Tessel -

method = POST
Partial body: {"ledidx":"2"}
Body: {"ledidx":"2"}
ledidx = 2


I'm running Windows 10 64bit with NodeJS 6.10.2.

Tessel Environment Versions

  • t2-cli: 0.1.8
  • t2-firmware: 0.1.0
  • Node.js: 6.10.3


My favorite development tools are -

File Editing

Image Editing

Version Control


  • Postman : An excellent tool for testing servers and APIs. Included in this repo are two files containing exports of collections used in testing -

  • Tessel.postman_collection-v1.json - A version 1 Postman collection

  • Tessel.postman_collection-v2.json - A version 2 Postman collection

Both contain the following -

Tessel - HTTP GET - Requests / and gets index.html in the response.

Tessel - HTTP GET favicon - Requests /favicon.ico.

Tessel - HTTP GET leds - Requests /leds/2 and toggles the green LED.

Tessel - HTTP POST LEDS - Posts {"ledidx":2} to toggle the green LED.

The server will respond with {"on":false} or {"on":true} depending on the state of the LED after it was toggled.

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