pipoint: add a driver for the Raspberry Pi servoblaster.

servoblaster.go

@@ -0,0 +1,43 @@
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package pipoint
+
+import (
+	"fmt"
+	"os"
+
+	"gobot.io/x/gobot/sysfs"
+)
+
+const (
+	path = "/dev/servoblaster"
+)
+
+type ServoBlaster struct {
+	Pin int
+}
+
+// SetDuty sets the servo period in ns.
+func (s *ServoBlaster) SetDuty(period int) (err error) {
+	file, err := sysfs.OpenFile(path, os.O_WRONLY, 0644)
+	defer file.Close()
+	if err != nil {
+		return
+	}
+
+	_, err = file.Write([]byte(fmt.Sprintf("%d=%dus\n", s.Pin, period/1000)))
+	return err
+}