Ultrasonic Sensor

[sgilani]

Hi,

i have now no ideas anymore, how can a get the distance from a Ultrasonic Sensor and Arduino with Gobot.

Can you give me a Tip, i am stocked here:

//----------AND NOW??--------------// //This is the Part from a Arduino Sketch duration = pulseIn(echoPin, HIGH) //--------------------------------//

I have no idea how to dev. this in Go "pulseIn(echoPin, HIGH)"

package main

import ( "fmt" "time"

"github.com/hybridgroup/gobot"
"github.com/hybridgroup/gobot/platforms/firmata"
"github.com/hybridgroup/gobot/platforms/gpio"

)

func main() { gbot := gobot.NewGobot()

firmataAdaptor := firmata.NewFirmataAdaptor("firmata", "COM7")
trigPin := gpio.NewDirectPinDriver(firmataAdaptor, "sensor", "11")
echoPin := gpio.NewDirectPinDriver(firmataAdaptor, "sensor", "12")
led := gpio.NewLedDriver(firmataAdaptor, "led", "13")

work := func() {

    maximumRange := 200
    minimumRange := 0

    duration := 0
    distance := 0

    gobot.Every(100*time.Millisecond, func() {

        trigPin.DigitalWrite(byte(0))
        time.Sleep(2 * time.Microsecond)

        trigPin.DigitalWrite(byte(1))
        time.Sleep(10 * time.Microsecond)

        trigPin.DigitalWrite(byte(0))

        //----------AND NOW??--------------//
        //This is the Part from Arduino Sketch
        duration = pulseIn(echoPin, HIGH)
        //--------------------------------//

        //Calculate the distance (in cm) based on the speed of sound.
        distance = duration / 58

        if distance > maximumRange || distance < minimumRange {
            /* Send a negative number to computer and Turn LED ON
            to indicate "out of range" */
            fmt.Println("-1")
            led.On()
        } else {
            /* Send the distance to the computer using Serial protocol, and
            turn LED OFF to indicate successful reading. */
            fmt.Println(distance)
            led.Off()
        }

    })

}

robot := gobot.NewRobot("makeyBot",
    []gobot.Connection{firmataAdaptor},
    []gobot.Device{trigPin, echoPin, led},
    work,
)

gbot.AddRobot(robot)

gbot.Start()

}

[sgilani]

:(( NO not directly, by the end i did it with node.js and from GO i do now a API call to node.js to get the values inside of Go.

This is just a bad unfriendly workaround. I am sorry...

[deadprogram]

Well, in that case I am closing this issue :sob:

All joking aside, I think this is a duplicate of https://github.com/hybridgroup/gobot/issues/152

Bottom line is I need to work on this!

[billettc]

Here your solution ...

`package main

import ( "gobot.io/x/gobot/platforms/raspi" "gobot.io/x/gobot/drivers/gpio" "gobot.io/x/gobot" "time" "fmt" )

func main() { r := raspi.NewAdaptor()

trigPin := gpio.NewDirectPinDriver(r, "11")
echoPin := gpio.NewDirectPinDriver(r, "12")
led := gpio.NewLedDriver(r, "7")

work := func() {

	gobot.Every(1 * time.Second, func() {

		println("Starting probing ")
		led.Toggle()

		trigPin.DigitalWrite(byte(0))
		time.Sleep(2 * time.Microsecond)

		trigPin.DigitalWrite(byte(1))
		time.Sleep(10 * time.Microsecond)

		trigPin.DigitalWrite(byte(0))
		start := time.Now()
		end := time.Now()

		for {
			val, err := echoPin.DigitalRead();
			start = time.Now()

			if (err != nil) {
				println(err)
				break
			}

			if val == 0 { continue }

			break
		}

		for {
			val, err := echoPin.DigitalRead();
			end = time.Now()
			if (err != nil) {
				println(err)
				break
			}

			if val == 1 {
				continue
			}

			break
		}


		duration := end.Sub(start)
		durationAsInt64 := int64(duration)
		distance := duration.Seconds() * 34300
		distance = distance / 2 //one way travel time
		fmt.Printf("Duration : %v %v %v \n", distance, duration.Seconds(), durationAsInt64)
	})
}

robot := gobot.NewRobot("makeyBot",
	[]gobot.Connection{r},
	[]gobot.Device{trigPin, echoPin, led},
	work,
)

robot.Start()

}`

[stevemcquaid]

@billettc - thanks so much for providing this!

Unfortunately in my testing, the latency was so bad over the network (wifi) that measurements were unusable. Personally, I think that the time differential really needs to be measured and computed on the hardware itself. Network latency can add +-10 full milliseconds even under the best conditions. (Plus it would stink to have measurements change as a function of distance from wifi router.)

I ended up sending this PR to firmata to hopefully expose a pulseIn hook that gobot would be able to implement and use to achieve these measurements.

https://github.com/firmata/arduino/pull/396

[wlwatkins]

Have there been any updates on this mater?

[gen2thomas]

An alternative sensor would be the SRF08 I2C sensor, see #327

[gen2thomas]

I'm going to close this issue, because there will be no good solution for this requirement. Please see the referenced issues for better alternatives.