In the previous articles I talked about the GE Hackathon, using WICED and CapSense, and finally creating a Particle Photon configuration.  In this article I will show you the WICED HTTP Client firmware which will read the button state and send it via WICED HTTP to the Particle Cloud.  To build this project I will start from the I2C Read firmware that I talked about in this article.

There are two parts of this application

  • The “main” application which reads the buttons and sends a message
  • The “sendMessage” function which builds a WICED HTTP message and sends it to the Particle cloud.

Main Application

I took the code from the previous example (CY3280 –> I2C –> WICED) and only made a few modifications (though I rearranged things a bit to make it easier to look at)

  • I joined the network (line 126)
  • I look up the IP address of the Particle Cloud (line 128)
  • Then I send a HIGH or LOW via the sendMessage function based on the state of the buttons (all the buttons do the same thing)

Send Message via WICED HTTP

The WICED HTTP sendMessage function simply

  • Creates a http_client (which is just a mechanism to keep track of an HTTP connection
  • Sets up a connection (lines 77-80)
  • Makes the connection (line 82)
  • Creates the message (line 88) in “application/x-www-form-urlencoded” format
  • Builds the HTTP headers for a HTTP “POST” (lines 90-105)
  • Write the Request (lines 108 –> 112)
  • Waits for the response using semaphore (line 114)
  • Destroys the connection (line 115 –> 116)

WICED HTTP Event Handler

The way that the WICED HTTP  executes is that it has a worker thread waiting on the TCP socket.  When it gets a response it runs your callback function and tells you what happened.  In this case I just tell my thread to close the connection and move on.