are defined in a separate library, and the header file provides an interface. Many times, the implementation of these functions, constants, classes, etc. mbed.h is a header file that declares a set of functions, constants, classes, etc. copy into our program) a separate file (mbed.h in this case) when we compile. The very first line in our blinky program is language:c You would need to reset the microcontroller to restart the program. It is possible to make the while loop exit, and the program would stop running. Notice that we explicitly put the loop code inside of a while loop. Much like in the Arduino example, the program executes the setup code once (as soon as it enters the main() function) and executes the loop code forever. Using our concepts of setup and loop, this is what the basic template looks like in mbed: language:c this is where the program begins execution when you run it). Every C and C++ program must have a main() function, as this is the entry point for the program (i.e. In mbed (and most other embedded systems), we must create our own setup and loop sections within main(). In Arduino, the setup code runs once, and the loop code runs forever. For example, you might see this in Arduino: language:c One thing you should be aware of is that Arduino wraps up the setup and loop stages into nice functions for you. If you have used Arduino in the past, it might come as a surprise that you were writing code in a language very close to C and C++. This is our first program with the mbed, so we should talk about what is going on. In the final project, we load some sound clips onto our SD card and use the mbed to play one whenever we push a button. Let's make some music! We can use pulse-width modulation (PWM) to control sounds out of a speaker or set of headphones. Want to see how the temperature varies over time in an area? We connect a temperature sensor and an SD card to the mbed to log temperature measurements. In addition to acting like a USB host, the mbed can also act like a USB device! This means that we can have it control the mouse pointer on our computer, for example. This means that we can connect things like keyboards to it. Using an Ethernet cable, we can read the current time from an Internet server and display the time on our LCD. The LPC1768 has the ability to connect to the Internet. Using the accelerometer, we can interact with the mbed by tilting it in different directions. We learn how to draw text and shapes on the LCD. The mbed kit includes a 1.44" LCD that we can make do cool things. Let's make some light! We use some buttons to control the colors of an RGB LED We setup the development environment and create our first program: Blinky! You should start with Tutorial #1 in order to get familiar with and the programming environment. The tutorials! This is where you get to open your mbed kit and play with all those cool parts. This library contains code for a *.wav audio player that is used to play music.Now for the part you have been waiting for. The links below will bring in the required include files into a new project in the online compiler to get started. Audio files will play at around 15Khz in mono on the LPC7168 mbed's D/A, and the video frame rate is near 15 frames per second on the color LCD.Ī PDF of the instructions provided to students for this assignment is available. The smart color LCD, small speaker, microSD card breakout, and audio jack breakout board seen in the breadboard below are all available from Sparkfun.Īudacity was used to downsample and prepare the *.wav audio files for the SD card and the free 4D Systems Workshop IDE tool was used to resample the video clips for the small 128 by 128 color LCD's SD card. Students purchase their own mbed parts kit, and already have a breadboard and jumper wire kit available from prior laboratory classes.Īn audio jack breakout drives a PC speaker, or the small black PC mount speaker and driver circuit on the breadboard can be used for audio output. Easy to use include files pull in the reusable C++ class code modules for each of these devices, and cookbook Wiki pages provide the details of how they all work and are wired on the breadboard. Four small software debounced pushbuttons from Parallax control the player and the songs displayed in the LCD's menu are read from the micro SD card's directory. The mPod was built at Georgia Tech in the ECE sophomore level C++ programming class as a mid-term two-week student laboratory project using the mbed cookbook's *.wav file waveplayer for audio output from the D/A, the SDfilesystem to read microSD card music files, and the uLCD 144 driver to play the video clips.
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