- support for servo blaster

- servo requires the underlying PWM to support a SetMicroseconds method

motion/servo/servo.go

@@ -9,43 +9,35 @@ import (
 
 // A PWM interface implements access to a pwm controller.
 type PWM interface {
-	SetPwm(channel int, onTime int, offTime int) error
+	SetMicroseconds(channel int, us int) error
 }
 
 type Servo struct {
 	PWM     PWM
-	Freq    int
 	Channel int
 
-	Minms, Maxms float64
+	Minus, Maxus int
 
 	Debug bool
 }
 
 // New creates a new Servo interface.
-// pwm: instance of a PWM controller.
-// freq: Frequency of pwm signal (typically 50Hz)
-// channel: PWM channel of the pwm controller to be used
-// minms: Pulse width corresponding to servo position of 0deg
-// maxms: Pulse width corresponding to servo position of 180deg
-func New(pwm PWM, freq, channel int, minms, maxms float64) *Servo {
+func New(pwm PWM, channel int, minus, maxus int) *Servo {
 	return &Servo{
 		PWM:     pwm,
-		Freq:    freq,
 		Channel: channel,
-		Minms:   minms,
-		Maxms:   maxms,
+		Minus:   minus,
+		Maxus:   maxus,
 	}
 }
 
 // SetAngle sets the servo angle.
 func (s *Servo) SetAngle(angle int) error {
-	us := util.Map(int64(angle), 0, 180, int64(s.Minms*1000), int64(s.Maxms*1000))
-	offTime := int(us) * s.Freq * 4096 / 1000000
+	us := util.Map(int64(angle), 0, 180, int64(s.Minus), int64(s.Maxus))
 
 	if s.Debug {
-		log.Printf("servo: given angle %v calculated %v us offTime %v", angle, us, offTime)
+		log.Printf("servo: given angle %v calculated %v us", angle, us)
 	}
 
-	return s.PWM.SetPwm(s.Channel, 0, offTime)
+	return s.PWM.SetMicroseconds(s.Channel, int(us))
 }