First implementation

actuator/pca9685.go

@@ -0,0 +1,39 @@
+package actuator
+
+import (
+	"log"
+	"periph.io/x/periph/conn/i2c/i2creg"
+	"periph.io/x/periph/conn/physic"
+	"periph.io/x/periph/experimental/devices/pca9685"
+	"periph.io/x/periph/host"
+)
+
+var (
+	device *pca9685.Dev
+)
+
+func init() {
+	log.Print("init pca9685 controller")
+	_, err := host.Init()
+	if err != nil {
+		log.Fatalf("unable to init host: %v", err)
+	}
+
+	log.Print("open i2c bus")
+	bus, err := i2creg.Open("")
+	if err != nil {
+		log.Fatalf("unable to init i2c bus: %v", err)
+	}
+	log.Print("i2c bus opened")
+
+	device, err = pca9685.NewI2C(bus, pca9685.I2CAddr)
+	if err != nil {
+		log.Fatalf("unable to init pca9685 bus: %v", err)
+	}
+	log.Printf("set pwm frequency to %d", 60)
+	err = device.SetPwmFreq(60 * physic.Hertz)
+	if err != nil {
+		log.Fatalf("unable to set pwm frequency: %v", err)
+	}
+	log.Print("init done")
+}

actuator/steering.go

@@ -0,0 +1,44 @@
+package actuator
+
+import (
+	"github.com/cyrilix/robocar-pca9685/util"
+	"log"
+	"periph.io/x/periph/conn/gpio"
+	"periph.io/x/periph/experimental/devices/pca9685"
+)
+
+const (
+	LeftAngle  = -1.
+	RightAngle = 1.
+)
+
+type Steering struct {
+	channel           int
+	leftPWM, rightPWM int
+	dev               *pca9685.Dev
+}
+
+func (s *Steering) SetPulse(pulse int) {
+	err := s.dev.SetPwm(s.channel, 0, gpio.Duty(pulse))
+	if err != nil {
+		log.Printf("unable to set throttle pwm value: %v", err)
+	}
+
+}
+
+// Set percent value steering
+func (s *Steering) SetPercentValue(p float64) {
+	// map absolute angle to angle that vehicle can implement.
+	pulse := util.MapRange(p, LeftAngle, RightAngle, float64(s.leftPWM), float64(s.rightPWM))
+	s.SetPulse(pulse)
+}
+
+func NewSteering(channel, leftPWM, rightPWM int) *Steering {
+	t := Steering{
+		channel:  channel,
+		dev:      device,
+		leftPWM:  leftPWM,
+		rightPWM: rightPWM,
+	}
+	return &t
+}

actuator/throttle.go

@@ -0,0 +1,53 @@
+package actuator
+
+import (
+	"github.com/cyrilix/robocar-pca9685/util"
+	"log"
+	"periph.io/x/periph/conn/gpio"
+	"periph.io/x/periph/experimental/devices/pca9685"
+)
+
+const (
+	MinThrottle = -1
+	MaxThrottle = 1
+)
+
+type Throttle struct {
+	channel                       int
+	zeroPulse, minPulse, maxPulse int
+	dev                           *pca9685.Dev
+}
+
+func (t *Throttle) SetPulse(pulse int) {
+	err := t.dev.SetPwm(t.channel, 0, gpio.Duty(pulse))
+	if err != nil {
+		log.Printf("unable to set throttle pwm value: %v", err)
+	}
+
+}
+
+// Set percent value throttle
+func (t *Throttle) SetPercentValue(p float64) {
+	var pulse int
+	if p > 0 {
+		pulse = util.MapRange(p, 0, MaxThrottle, float64(t.zeroPulse), float64(t.maxPulse))
+	} else {
+		pulse = util.MapRange(p, MinThrottle, 0, float64(t.minPulse), float64(t.zeroPulse))
+	}
+	t.SetPulse(pulse)
+}
+
+func NewThrottle(channel, zeroPulse, minPulse, maxPulse int) *Throttle {
+	t := Throttle{
+		channel:   channel,
+		dev:       device,
+		zeroPulse: zeroPulse,
+		minPulse:  minPulse,
+		maxPulse:  maxPulse,
+	}
+
+	log.Printf("send zero pulse to calibrate ESC: %v", zeroPulse)
+	t.SetPulse(zeroPulse)
+
+	return &t
+}