Go实现树莓派超声波测距

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后面发现调用的两个Go的库进行测算还是没办法读到好的超声波值， 所以放弃

公式

距离(cm)=（(声速(m/s)×时间(ms)）/ 2） *10

代码

ultrasonicSensor.go

package mainimport ("context""errors""fmt""periph.io/x/conn/v3/gpio""periph.io/x/conn/v3/gpio/gpioreg""time"
)var (TimeoutError = errors.New("timeout error")
)const (SpeedOfSound = 34300.0 // cm/s
)type UltrasonicSensor struct {triggerIO gpio.PinIOechoIO    gpio.PinIOstarted  boolcanceled chan struct{}
}func NewUltrasonicSensor(triggerPinName, echoPinName string) (*UltrasonicSensor, error) {var (us = &UltrasonicSensor{canceled: make(chan struct{}),}err error)us.triggerIO = gpioreg.ByName(triggerPinName)if nil == us.triggerIO {return nil, errors.New("can't find trigger pin")}us.echoIO = gpioreg.ByName(echoPinName)if nil == us.echoIO {return nil, errors.New("can't find echo pin")}return us, err
}func (u *UltrasonicSensor) Init() error {err := u.triggerIO.Out(gpio.Low)if nil != err {return err}err = u.echoIO.In(gpio.PullDown, gpio.NoEdge)return nil
}func (u *UltrasonicSensor) Destroy() error {return nil
}func (u *UltrasonicSensor) Start(detectInterval time.Duration, onDistanceChanged func(cm float64, err error) error) error {go u.run(detectInterval, onDistanceChanged)return nil
}func (u *UltrasonicSensor) run(detectInterval time.Duration, onDistanceChanged func(cm float64, err error) error) {if u.started {return}u.started = truedefer func() {select {case <-u.canceled:default:}u.started = false}()var (err          errordistance     float64distanceTemp float64/*声速大约是343米/秒, 超声波模块最大测量是2m ~ 6m时间(s) = 2*距离(m)/声速(m/s) = 2 * 6 / 343 ≈ 0.035*/maxWaitTime = time.Millisecond * 35 //35parentCtx   = context.Background()ctx         context.Context)for {err = u.ultrasonicPulseOut() // 发送超声波if nil != err {onDistanceChanged(0, err)return}ctx, _ = context.WithTimeout(parentCtx, maxWaitTime)distanceTemp, err = u.getDist(ctx)if nil != err {if TimeoutError != err {onDistanceChanged(0, err)return}fmt.Println("read timeout")time.Sleep(detectInterval)continue}if distance != distanceTemp {distance = distanceTempif err = onDistanceChanged(distance, nil); nil != err {return}}time.Sleep(detectInterval)}
}func (u *UltrasonicSensor) ultrasonicPulseOut() (err error) {if err = u.triggerIO.Out(gpio.High); nil != err {return err}time.Sleep(time.Microsecond * 10) // 10usif err = u.triggerIO.Out(gpio.Low); nil != err {return err}time.Sleep(time.Microsecond * 1)return
}func (u *UltrasonicSensor) getDist(ctx context.Context) (float64, error) {var (startDateTime time.Time // 开启超声波计时)waitForNext := func() error {select {case <-ctx.Done():return TimeoutErrorcase <-u.canceled:return errors.New("cancel error")case <-time.After(time.Nanosecond * 1): // 读取引脚延时，也是软件最大误差}return nil}/* wait for start */for gpio.Low == u.echoIO.Read() {if err := waitForNext(); nil != err {return 0, err}}startDateTime = time.Now()/* wait for end */for gpio.High == u.echoIO.Read() {if err := waitForNext(); nil != err {return 0, err}}return time.Since(startDateTime).Seconds() * SpeedOfSound / 2.0, nil
}func (u *UltrasonicSensor) Stop() error {if !u.started {return nil}select {case u.canceled <- struct{}{}:case <-time.After(time.Second * 2):return errors.New("cancel timeout")}return nil
}

main.go

package mainimport ("fmt""log""periph.io/x/host/v3""sync""time"
)func main() {var (waiter sync.WaitGroup)// 初始化硬件if _, err := host.Init(); err != nil {log.Fatal(err)}sensor, err := NewUltrasonicSensor("GPIO17", "GPIO27")if nil != err {fmt.Println(err)return}if err = sensor.Init(); nil != err {fmt.Println("sensor init fail, ", err.Error())return}defer sensor.Destroy()waiter.Add(1)sensor.Start(time.Second, func(cm float64, err error) error {if nil != err {waiter.Done()fmt.Println(err)return err}fmt.Println("Distance ", cm, "(cm)")return nil})waiter.Wait()
}

Note

注意电源一定要选对， 否则输出功率不够无法准确测量距离…

参考

树莓派|超声波传感器

GPIO-ZERO DistanceSensor

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