Introduction

New to using dragonboards? We have for you two really simple projects to help you get started with some basics. We will be using a dragonboard and a Sensors Mezzanine Board for the same. Meant for beginners, these projects go through some of the very basic concepts like connecting the Mezzanine board with the dragonboard, interfacing an LCD and a Touch Sensor Module with the board and installing the necessary libraries.

In the Digital Hourglass project, we will basically build a timer which takes in user input for the time to be measured and prints a character on the display at certain intervals till the time is up. Here, I have implemented a count-up timer which flashes “TIME UP” on the display in the end.

The Magic 8 Ball application displays messages on the LCD when the touch sensor module is tapped. There are 20 statements out of which any one can appear randomly at each tap on the sensor. So let’s begin!

Prerequisites

Hardware requirements

Package dependencies

Make sure you have the following two libraries installed along with the source code.

UPM Library

$ sudo apt-get install libupm-dev

MRAA Library

$ sudo apt-get install libmraa-dev

Source Code

$ git clone https://github.com/96boards-projects/hourglass
$ git clone https://github.com/96boards-projects/magic8

Instructions

Now that you have the libraries and the source code ready, let’s begin with hardware connections. Always make sure that the power supply is NOT connected while making or modifying any connections. First, connect the Sensors Mezzanine board onto the dragonboard via the low-speed expansion connector on both boards. Instructions to do that can be found here. Use the Grove Universal 4 pin cables to connect the LCD to I2C0 and the touch sensor module on GPIO G3. That’s it! We’re all set to run our application.

If you change the working directory to hourglass, you will find a makefile and the source code. You can go through the code to get an idea of what exactly is happening. While including the .h files, make sure that the path to the library matches the one in your system. Now, you can go ahead to build and execute the program.

$ cd hourglass
$ make
$ ./hourglass

You can see that the display has the initial message printed on it which prompts the user to enter time in minutes. Once you enter the time, you will find the LCD filling up with characters till the time is up.

Similarly for the magic 8 ball application,

$ cd magic8
$ make
$ ./magic8

In this application, the input is nothing but the touch sensor readings. Every time a tap gets detected on the sensor, it generates a random number from 0-19 using the rand() function. Associated with each number is a string that is displayed onto the LCD. You can play around with the code to modify the statements

Conclusion

So that’s about it in this one! These projects should help you get started with 96Boards and get comfortable with the working environment.

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