make ultrasonic timeout configurable

components/sensor/ultrasonic/ultrasonic.go

@@ -24,6 +24,7 @@ type AttrConfig struct {
 	TriggerPin    string `json:"trigger_pin"`
 	EchoInterrupt string `json:"echo_interrupt_pin"`
 	Board         string `json:"board"`
+	TimeoutMs     uint   `json:"timeout_ms,omitempty"`
 }
 
 // Validate ensures all parts of the config are valid.
@@ -88,6 +89,13 @@ func newSensor(ctx context.Context, deps registry.Dependencies, name string, con
 	if err := s.triggerPin.Set(ctx, false, nil); err != nil {
 		return nil, errors.Wrap(err, "ultrasonic: cannot set trigger pin to low")
 	}
+
+	if config.TimeoutMs > 0 {
+		s.timeoutMs = config.TimeoutMs
+	} else {
+		// default to 1 sec
+		s.timeoutMs = 1000
+	}
 	s.intChan = make(chan bool)
 	s.echoInterrupt.AddCallback(s.intChan)
 	return s, nil
@@ -100,6 +108,7 @@ type Sensor struct {
 	echoInterrupt board.DigitalInterrupt
 	triggerPin    board.GPIOPin
 	intChan       chan bool
+	timeoutMs     uint
 	generic.Unimplemented
 }
 
@@ -119,15 +128,15 @@ func (s *Sensor) Readings(ctx context.Context, extra map[string]interface{}) (ma
 		timeB = time.Now()
 	case <-ctx.Done():
 		return nil, errors.New("ultrasonic: context canceled")
-	case <-time.After(time.Second * 1):
+	case <-time.After(time.Millisecond * time.Duration(s.timeoutMs)):
 		return nil, errors.New("ultrasonic timeout")
 	}
 	select {
 	case <-s.intChan:
 		timeA = time.Now()
 	case <-ctx.Done():
 		return nil, errors.New("ultrasonic: context canceled")
-	case <-time.After(time.Second * 1):
+	case <-time.After(time.Millisecond * time.Duration(s.timeoutMs)):
 		return nil, errors.New("ultrasonic timeout")
 	}
 	dist := timeA.Sub(timeB).Seconds() * 340 / 2