Add support for attached motion sensor on GPIO

This assumes running on Raspberry Pi, using an HC-SR501. This device
outputs a HIGH signal when motion is detected, or a low signal when
no motion is detected after a certain delay.

Can be set by specifying --motion-pin to the GPIO pin on the raspberry
to which the HC-SR501 data pin is connected.

Implements #5

cmd/hkcam/main.go

@@ -2,13 +2,19 @@ package main
 
 import (
 	"flag"
+
 	"github.com/brutella/hc"
 	"github.com/brutella/hc/accessory"
 	"github.com/brutella/hc/log"
+	"github.com/brutella/hc/service"
+
+	"github.com/stianeikeland/go-rpio/v4"
 
 	"image"
 	"runtime"
 
+	"time"
+
 	"github.com/brutella/hkcam"
 	"github.com/brutella/hkcam/ffmpeg"
 )
@@ -21,13 +27,15 @@ func main() {
 	var loopbackFilename *string
 	var h264Encoder *string
 	var h264Decoder *string
+	var motionPin int = -1
 
 	if runtime.GOOS == "linux" {
 		inputDevice = flag.String("input_device", "v4l2", "video input device")
 		inputFilename = flag.String("input_filename", "/dev/video0", "video input device filename")
 		loopbackFilename = flag.String("loopback_filename", "/dev/video1", "video loopback device filename")
 		h264Decoder = flag.String("h264_decoder", "", "h264 video decoder")
 		h264Encoder = flag.String("h264_encoder", "h264_omx", "h264 video encoder")
+		flag.IntVar(&motionPin, "motion_pin", -1, "GPIO pin of any attached motion sensor")
 	} else if runtime.GOOS == "darwin" { // macOS
 		inputDevice = flag.String("input_device", "avfoundation", "video input device")
 		inputFilename = flag.String("input_filename", "default", "video input device filename")
@@ -63,6 +71,25 @@ func main() {
 		MultiStream:      *multiStream,
 	}
 
+	// Add Motion Sensor
+	if motionPin != -1 {
+		err := rpio.Open()
+		if err != nil {
+			log.Info.Panic(err)
+		}
+		pin := rpio.Pin(10)
+		pin.Input()
+
+		motionSensor := service.NewMotionSensor()
+		cam.AddService(motionSensor.Service)
+
+		go func() {
+			for range time.Tick(time.Second) {
+				motionSensor.MotionDetected.SetValue(pin.Read() == rpio.High)
+			}
+		}()
+	}
+
 	ffmpeg := hkcam.SetupFFMPEGStreaming(cam, cfg)
 
 	// Add a custom camera control service to record snapshots

go.mod

@@ -6,4 +6,5 @@ require (
 	github.com/brutella/hc v1.2.0
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646
 	github.com/radovskyb/watcher v1.0.6
+	github.com/stianeikeland/go-rpio/v4 v4.4.0
 )

go.sum

@@ -13,6 +13,8 @@ github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 h1:zYyBkD/k9seD2A7fsi6
 github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646/go.mod h1:jpp1/29i3P1S/RLdc7JQKbRpFeM1dOBd8T9ki5s+AY8=
 github.com/radovskyb/watcher v1.0.6 h1:8WIQ9UxEYMZjem1OwU7dVH94DXXk9mAIE1i8eqHD+IY=
 github.com/radovskyb/watcher v1.0.6/go.mod h1:78okwvY5wPdzcb1UYnip1pvrZNIVEIh/Cm+ZuvsUYIg=
+github.com/stianeikeland/go-rpio/v4 v4.4.0 h1:LScvNyXHF412co42LG5t7bvBDbtDAhLF828ebaGqmjA=
+github.com/stianeikeland/go-rpio/v4 v4.4.0/go.mod h1:BkK52zk+FRk8wCTDf88/86Sojc+NfUiCAHd1ZV3RuTM=
 github.com/tadglines/go-pkgs v0.0.0-20140924210655-1f86682992f1 h1:ms/IQpkxq+t7hWpgKqCE5KjAUQWC24mqBrnL566SWgE=
 github.com/tadglines/go-pkgs v0.0.0-20140924210655-1f86682992f1/go.mod h1:roo6cZ/uqpwKMuvPG0YmzI5+AmUiMWfjCBZpGXqbTxE=
 golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9 h1:mKdxBk7AujPs8kU4m80U72y/zjbZ3UcXC7dClwKbUI0=