pullvalidate the css validate the css

Adam Harris
FabAcademy Projects

April 23nd 2014:   Networking

The discussion today focused on networking with embedded system.


Download my files for this week's project here

First Implementation (RS232)

    I began this week by designing a simple PCB in EagleCAD that could be used as either a node or a bridge device. I had first chosen to implement SLIP so I designed my board based on Neil's example SLIP code as I didn't see his design on the webpage (I later found that it was in the RS232 section). After trying to get my SLIP boards to communicate, I realized I needed to simplify my code to test whether or not my serial baud rate was correct for each board so I moved to the simple RS232 implementation instead. I am glad I did because I had to change my bit_delay to 101 for each of my boards. This proved to fix my communication problems.  I stuck with the RS232 to develop my node-to-node communication algorithm before moving on to SLIP.

  My board has 2 buttons in addition to the LED. The concept is that multiple devices will be connected together.  Each device has an address.  When a node receives a message addressed to it, it will flash an LED.  If a button is pressed on this device, it will take control of the medium and send out the address of another device on the network.    The left button will send a message to the current node's address -1, and the right button sends a message to the current node address +1.   This wraps around to create a loop.   I made 3 boards with the addresses 0,1, and 2.
 The buttons work as follows:

Current Node ID

Message sent when left button is pressed
Message sent when right button is pressed

1 2

2 0

0 1

    This results in the behavior shown in the video below.

Here is a link to all of my related files for this project.

Here are a couple of pictures of the boards. The first one shows all 3 nodes wired up to the FTDI cable, and the second picture shows a close-up of two nodes.

(Click this link if embedded video is not working)


Web template design: davereederdesign.com