pca9685: added gpio pin API (google#437)

experimental/devices/pca9685/pca9685.go

@@ -41,7 +41,8 @@ const (
 
 // Dev is a handler to pca9685 controller.
 type Dev struct {
-	dev *i2c.Dev
+	dev  *i2c.Dev
+	freq physic.Frequency
 }
 
 // NewI2C returns a Dev object that communicates over I2C.
@@ -90,6 +91,13 @@ func (d *Dev) init() error {
 
 // SetPwmFreq set the PWM frequency.
 func (d *Dev) SetPwmFreq(freqHz physic.Frequency) error {
+	if d.freq == freqHz {
+		// Don't need to write frequency if it's not changed.
+		// Note: this is required to avoid setting it each time
+		// when PWM value is changed via gpio.PinOut.PWM() API
+		return nil
+	}
+
 	p := (25*physic.MegaHertz/4096 + freqHz/2) / freqHz
 
 	modeRead := [1]byte{}
@@ -111,6 +119,7 @@ func (d *Dev) SetPwmFreq(freqHz physic.Frequency) error {
 	time.Sleep(100 * time.Millisecond)
 
 	_, err := d.dev.Write([]byte{mode1, oldmode | restart})
+	d.freq = freqHz
 	return err
 }
 

experimental/devices/pca9685/pca9685_test.go

@@ -0,0 +1,97 @@
+// Copyright 2020 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package pca9685
+
+import (
+	"testing"
+
+	"periph.io/x/periph/conn/gpio"
+	"periph.io/x/periph/conn/gpio/gpioreg"
+	"periph.io/x/periph/conn/i2c/i2ctest"
+	"periph.io/x/periph/conn/physic"
+)
+
+func TestPCA9685_pin(t *testing.T) {
+	scenario := &i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			// All leds cleared by init
+			{Addr: I2CAddr, W: []byte{allLedOnL, 0, 0, 0, 0}, R: nil},
+			// mode2 is set
+			{Addr: I2CAddr, W: []byte{mode2, outDrv}, R: nil},
+			// mode1 is set
+			{Addr: I2CAddr, W: []byte{mode1, allCall}, R: nil},
+			// mode1 is read and sleep bit is cleared
+			{Addr: I2CAddr, W: []byte{mode1}, R: []byte{allCall | sleep}},
+			{Addr: I2CAddr, W: []byte{mode1, allCall | ai}, R: nil},
+
+			// SetPwmFreq 50 Hz
+			// Read mode
+			{Addr: I2CAddr, W: []byte{0x00}, R: []byte{allCall | ai}},
+			// Set sleep
+			{Addr: I2CAddr, W: []byte{0x00, allCall | ai | sleep}, R: nil},
+			// Set prescale
+			{Addr: I2CAddr, W: []byte{prescale, 122}, R: nil},
+			// Clear sleep
+			{Addr: I2CAddr, W: []byte{0x00, allCall | ai}, R: nil},
+			// Set Restart
+			{Addr: I2CAddr, W: []byte{0x00, allCall | ai | restart}, R: nil},
+
+			// Set PWM value of pin 0 to 50%
+			{Addr: I2CAddr, W: []byte{led0OnL, 0, 0, 0, 128}, R: nil},
+		},
+	}
+
+	dev, err := NewI2C(scenario, I2CAddr)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err = dev.RegisterPins(); err != nil {
+		t.Fatal(err)
+	}
+
+	pin := gpioreg.ByName("PCA9685_40_0")
+	pin.PWM(gpio.DutyHalf, 50*physic.Hertz)
+}
+
+func TestPCA9685(t *testing.T) {
+	scenario := &i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			// All leds cleared by init
+			{Addr: I2CAddr, W: []byte{allLedOnL, 0, 0, 0, 0}, R: nil},
+			// mode2 is set
+			{Addr: I2CAddr, W: []byte{mode2, outDrv}, R: nil},
+			// mode1 is set
+			{Addr: I2CAddr, W: []byte{mode1, allCall}, R: nil},
+			// mode1 is read and sleep bit is cleared
+			{Addr: I2CAddr, W: []byte{mode1}, R: []byte{allCall | sleep}},
+			{Addr: I2CAddr, W: []byte{mode1, allCall | ai}, R: nil},
+
+			// SetPwmFreq 50 Hz
+			// Read mode
+			{Addr: I2CAddr, W: []byte{0x00}, R: []byte{allCall | ai}},
+			// Set sleep
+			{Addr: I2CAddr, W: []byte{0x00, allCall | ai | sleep}, R: nil},
+			// Set prescale
+			{Addr: I2CAddr, W: []byte{prescale, 122}, R: nil},
+			// Clear sleep
+			{Addr: I2CAddr, W: []byte{0x00, allCall | ai}, R: nil},
+			// Set Restart
+			{Addr: I2CAddr, W: []byte{0x00, allCall | ai | restart}, R: nil},
+
+			// Set PWM value of pin 0 to 50%
+			{Addr: I2CAddr, W: []byte{led0OnL, 0, 0, 0, 128}, R: nil},
+		},
+	}
+
+	dev, err := NewI2C(scenario, I2CAddr)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err = dev.SetPwm(0, 0, 0x8000); err != nil {
+		t.Fatal(err)
+	}
+}

experimental/devices/pca9685/pins.go

@@ -0,0 +1,124 @@
+// Copyright 2020 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package pca9685
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"time"
+
+	"periph.io/x/periph/conn/gpio"
+	"periph.io/x/periph/conn/gpio/gpioreg"
+	"periph.io/x/periph/conn/physic"
+	gpiopin "periph.io/x/periph/conn/pin"
+)
+
+const (
+	dutyMax gpio.Duty = math.MaxUint16
+)
+
+type pin struct {
+	dev     *Dev
+	channel int
+}
+
+// CreatePin creates a gpio handle for the given channel.
+func (d *Dev) CreatePin(channel int) (gpio.PinIO, error) {
+	if channel < 0 || channel >= 16 {
+		return nil, errors.New("PCA9685: Valid channel range is 0..15")
+	}
+	return &pin{
+		dev:     d,
+		channel: channel,
+	}, nil
+}
+
+// RegisterPins makes PWM channels available as PWM pins in the pin registry
+//
+// Pin names have the following format: PCA9685_<HexAddress>_<channel> (e.g. PCA9685_40_11)
+func (d *Dev) RegisterPins() error {
+	for i := 0; i < 16; i++ {
+		pin, err := d.CreatePin(i)
+		if err != nil {
+			return err
+		}
+		if err = gpioreg.Register(pin); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (p *pin) String() string {
+	return p.Name()
+}
+
+func (p *pin) Halt() error {
+	return p.Out(gpio.Low)
+}
+
+func (p *pin) Name() string {
+	return fmt.Sprintf("PCA9685_%x_%d", p.dev.dev.Addr, p.channel)
+}
+
+func (p *pin) Number() int {
+	return p.channel
+}
+
+func (p *pin) Function() string {
+	return string(p.Func())
+}
+
+func (p *pin) In(pull gpio.Pull, edge gpio.Edge) error {
+	return errors.New("PCA9685: Pin cannot be configured as input")
+}
+
+func (p *pin) Read() gpio.Level {
+	return gpio.INVALID.Read()
+}
+
+func (p *pin) WaitForEdge(timeout time.Duration) bool {
+	return false
+}
+
+func (p *pin) Pull() gpio.Pull {
+	return gpio.Float
+}
+
+func (p *pin) DefaultPull() gpio.Pull {
+	return gpio.Float
+}
+
+func (p *pin) Out(l gpio.Level) error {
+	return p.PWM(gpio.DutyMax, 0)
+}
+
+func (p *pin) PWM(duty gpio.Duty, freq physic.Frequency) error {
+	if err := p.dev.SetPwmFreq(freq); err != nil {
+		return err
+	}
+	// PWM duty scaled down from 24 to 16 bits
+	scaled := duty >> 8
+	if scaled > dutyMax {
+		scaled = dutyMax
+	}
+	return p.dev.SetPwm(p.channel, 0, scaled)
+}
+
+func (p *pin) Func() gpiopin.Func {
+	return gpio.PWM
+}
+
+func (p *pin) SupportedFuncs() []gpiopin.Func {
+	return []gpiopin.Func{gpio.PWM}
+}
+
+func (p *pin) SetFunc(f gpiopin.Func) error {
+	if f != gpio.PWM {
+		return fmt.Errorf("PCA9685: Function not supported: %s", f)
+	}
+	return nil
+}