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GPIO Driver Application

In this section a simple but effective example of the GPIO Driver on Wires will be presented. This example will implement a Wire graph that toggles a digital GPIO. A listener will be attached to an input GPIO externally connected to the first one.

Setup a Raspberry Pi as shown in GPIO Driver section. Add a cable from the LED contact near the red cable to pin 37 (gpio 26) on the RaspberryPi.

Configure Kura Wires GPIO Driver Application

  1. Install the GPIO Driver from the Eclipse Kura Marketplace.

  2. On the Kura web interface, instantiate a GPIO Driver:

    • Under "System", select "Drivers and Assets" and click on the "New Driver" button.
    • Select "org.eclipse.kura.driver.gpio" as "Driver Factory", type a name in to "Driver Name" and click "Apply": a new driver will be instantiated and shown up under the "Drivers and Assets" tab.

  3. From the "Drivers and Assets" tab, add a new asset bound to the GPIO driver:

    • Click on the "New Asset" button and fill the form with the "Asset Name" and selecting the driver created in step 2. as "Driver Name". Click "Apply" and a new asset will be listed under the GPIO driver.
    • Click on the new asset and configure it, adding only one channel called LED as shown in the following picture:

    GPIO Example Led Asset

    • Click "Apply".

  4. As in point 3., create a new asset as shown below:

    GPIO Example Led Feedback Asset

    • Click "Apply".

  5. Click on "Wires" under "System".

  6. Add a new "Timer" component and configure the interval at which the LED will be toggled.

  7. Add a new "Script Filter" (it can be downloaded from the Eclipse Marketplace and configure it with the following script:

    // create a persistent counter
counter = typeof(counter) === 'undefined' ? 0 : counter
counter++

// emit the counter value in a different WireRecord
var counterRecord = newWireRecord()
counterRecord.LED = newBooleanValue(counter%2==0)
output.add(counterRecord)

  8. Add the "Asset" created at point 3 and connect the "Timer" to the "Filter" and the latter to the "Asset".

  9. Add the "Asset" created at point 4.

  10. Add "Logger" component and set log.verbosity to "VERBOSE".

  11. Connect the latter "Asset" to the "Logger". The resulting Wire Graph should be as below:

    GPIO Example Wire Graph

  12. Click on "Apply". After a while, the led on the breadboard should start to blink at a rate defined by the "Timer" as shown below:

    GPIO Example Blinking Led

    Moreover, the kura.log file should show a long sequencce of messages reporting that the value from the input gpio is changed:

    2018-04-09 13:08:42,990 [Thread-3289] INFO  o.e.k.i.w.l.Logger - Received WireEnvelope from org.eclipse.kura.wire.WireAsset-1523276074484-23
2018-04-09 13:08:42,991 [Thread-3289] INFO  o.e.k.i.w.l.Logger - Record List content: 
2018-04-09 13:08:42,992 [Thread-3289] INFO  o.e.k.i.w.l.Logger -   Record content: 
2018-04-09 13:08:42,993 [Thread-3289] INFO  o.e.k.i.w.l.Logger -     LED_Feedback : false
2018-04-09 13:08:42,993 [Thread-3289] INFO  o.e.k.i.w.l.Logger -     assetName : GPIOAssetFeedback
2018-04-09 13:08:42,994 [Thread-3289] INFO  o.e.k.i.w.l.Logger -     LED_Feedback_timestamp : 1523279322990
2018-04-09 13:08:42,994 [Thread-3289] INFO  o.e.k.i.w.l.Logger - 
2018-04-09 13:08:44,988 [Thread-3291] INFO  o.e.k.i.w.l.Logger - Received WireEnvelope from org.eclipse.kura.wire.WireAsset-1523276074484-23
2018-04-09 13:08:44,989 [Thread-3291] INFO  o.e.k.i.w.l.Logger - Record List content: 
2018-04-09 13:08:44,989 [Thread-3291] INFO  o.e.k.i.w.l.Logger -   Record content: 
2018-04-09 13:08:44,989 [Thread-3291] INFO  o.e.k.i.w.l.Logger -     LED_Feedback : true
2018-04-09 13:08:44,989 [Thread-3291] INFO  o.e.k.i.w.l.Logger -     assetName : GPIOAssetFeedback
2018-04-09 13:08:44,989 [Thread-3291] INFO  o.e.k.i.w.l.Logger -     LED_Feedback_timestamp : 1523279324988