Motor controlled via L293D.

MainActivity.kt

package com.madebyatomicrobot.things

import android.app.Activity
import android.os.Bundle
import android.util.Log
import com.google.android.things.pio.Gpio
import com.google.android.things.pio.PeripheralManagerService
import java.io.IOException


class MainActivity : Activity() {
    companion object {
        private val TAG = MainActivity::class.java.simpleName
    }

    lateinit var gpio17: Gpio
    lateinit var gpio18: Gpio
    lateinit var gpio27: Gpio

    var motorOn = false
    var clockwise = false

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val manager = PeripheralManagerService()
        try {
            Log.i(TAG, "GPIO: " + manager.gpioList)

            gpio17 = manager.openGpio("BCM17")
            gpio17.setDirection(Gpio.DIRECTION_OUT_INITIALLY_LOW)
            gpio17.setActiveType(Gpio.ACTIVE_HIGH)
            gpio17.value = false

            gpio18 = manager.openGpio("BCM18")
            gpio18.setDirection(Gpio.DIRECTION_OUT_INITIALLY_LOW)
            gpio18.setActiveType(Gpio.ACTIVE_HIGH)
            gpio18.value = false

            gpio27 = manager.openGpio("BCM27")
            gpio27.setDirection(Gpio.DIRECTION_OUT_INITIALLY_LOW)
            gpio27.setActiveType(Gpio.ACTIVE_HIGH)
            gpio27.value = false
        } catch (ex: IOException) {
            Log.w(TAG, "Error in onCreate", ex)
        }

        findViewById(R.id.toggle).setOnClickListener { toggleOn() }
        findViewById(R.id.direction).setOnClickListener { toggleDirection() }
    }
    
    fun toggleOn() {
        motorOn = !motorOn
        updateMotor()
    }

    fun toggleDirection() {
        clockwise = !clockwise
        updateMotor()
    }

    fun updateMotor() {
        gpio27.value = motorOn
        gpio17.value = clockwise
        gpio18.value = !clockwise
    }

    override fun onDestroy() {
        try {
            gpio17.close()
            gpio18.close()
            gpio27.close()
        } catch (ex: IOException) {
            Log.w(TAG, "Error in onDestroy", ex)
        }

        super.onDestroy()
    }
}