Part II – Can you roll with a L3G4200D gyroscope, Arduino and Matlab?

TaskList:

• Connect to the Arduino
• Ask for data
• Plot angular rate data
• Roll the Plot!

We’ve seen a basic Matlab-Arduino serial communication here.

Fair enough, Let’s rock.

Change from the previous post the setup and the loop and add a SerialRoutine() that will handle the communication.

You can check the full Arduino sketch in Github.

We need to set up the serial communication as we did in the dedicated post (just use the Matlab code at the end of this page). Don’t forget to update the simbolic link to /dev/ttyS101. Check the serial port displayed at the bottom-right corner of the Arduino IDE and replace /dev/PORT with it.

userk@dopamine:~$  sudo rm /dev/ttyS101
userk@dopamine:~$  sudo ln -s /dev/PORT /dev/ttyS101

With the following code the script will ask us the desired samplerate.

Initialize the rolling plot with a 100 samples long buffer.

Please note that in the Arduino code we were using the ‘A’ character as the message header. Let’s use this as a weak validity check. Create a while loop in which we will ask Arduino to send us the angular rates we are looking for. Use the exit condition to catch a really fast velocity value to stop the program instead of pressing CTRL + C.

Now that we are “sure” that we are dealing with our message containing the angular rates, we can scan the received string, extract the information, fill the buffer and create 3 subplots.

Done! We have our flawless rolling plot setup.

• Mathworks reference: plot
• Mathworks reference: serial
• Mathworks reference: textscan