1. Internet of Things with Intel Edison Led sensor lab
Pierre Collet Intel Software

2. Libmraa

3. Libmraa Libmraa How to install How to compile with mraa
Mraa is a library which is going to help us to communicate with the pins on the board.
How to install
Today we are using a package for Yocto, the linux proposed by default on Edison.
~# echo "src mraa-upm > /etc/opkg/mraa-upm.conf
~# opkg update
~# opkg install libmraa0
How to compile with mraa
When you compile just link with the –lmraa flag

4. LedSensor lab with Libmraa
Hardware
For this example, you need : A LED, a resistor, a sensor and four cables.
Plug the LED
Plug in a serial way one cable to the resistor, to the LED, to the other cable.
Let’s plug the cables on the Digital pin 8 and the other on the ground (GND)
Plug the sensor
Plug the sensor between the analog input 0 (A0) and the 5V pin.

5. Libmraa
Ledsensor with mraa

6. Libmraa Sources and Binaries
Go to the directory named : mraaLedSensor.
In this directory, there is three examples of controlling the board with mraa.
blinkled: It makes the the LED blink
getanalog: It displays the value receive on the analog input 0
Ledsensor: It light up the LED if the value received on A0 is above a given threshold
The value of the threshold and the pin number are define thank to some #define at the top of each file. You can change those numbers as you wish.
In order to compile all these examples, just enter “make” when you are in the directory which contains the .c files.

7. Conclusion Low level direct access Libmraa
You can access GPIO directly from the command line.
Libmraa
But it’s a LOT easier to use a library like mraa.
With mraa, GPIO is simple.
And with mraa sample binaries, you can create scripts in various languages to access GPIO data.

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