go-embedded/embd
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unified servo and analog output support for pwms

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This commit is contained in:
Karan Misra 2014-04-02 17:25:28 +05:30
parent 9ab49745bc
commit fc887282bf
9 changed files with 181 additions and 40 deletions
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76
bbb.go
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@ -17,6 +17,9 @@ import (
"strconv"
"strings"
"time"
"github.com/golang/glog"
"github.com/kidoman/embd/util"
)
var bbbPins = PinMap{
@ -244,19 +247,22 @@ const (
// BBBPWMDefaultDuty represents the default duty (0ns) for pwm.
BBBPWMDefaultDuty = 0
// BBBPWMDefaultPeriod represents the default period (500000ns) for pwm.
// BBBPWMDefaultPeriod represents the default period (500000ns) for pwm. Equals 2000 Hz.
BBBPWMDefaultPeriod = 500000
// BBBPWMMaxPulseWidth represents the max period (1000000000ns) supported by pwm.
// BBBPWMMaxPulseWidth represents the max period (1000000000ns) supported by pwm. Equals 1 Hz.
BBBPWMMaxPulseWidth = 1000000000
)
type bbbPWMPin struct {
n string
duty *os.File
period *os.File
polarity *os.File
period int
polarity Polarity
dutyf *os.File
periodf *os.File
polarityf *os.File
initialized bool
}
@ -292,18 +298,22 @@ func (p *bbbPWMPin) init() error {
if err := p.ensurePeriodFileExists(basePath, 500*time.Millisecond); err != nil {
return err
}
if p.period, err = p.periodFile(basePath); err != nil {
if p.periodf, err = p.periodFile(basePath); err != nil {
return err
}
if p.duty, err = p.dutyFile(basePath); err != nil {
if p.dutyf, err = p.dutyFile(basePath); err != nil {
return err
}
if p.polarity, err = p.polarityFile(basePath); err != nil {
if p.polarityf, err = p.polarityFile(basePath); err != nil {
return err
}
p.initialized = true
if err := p.reset(); err != nil {
return err
}
return nil
}
@ -372,8 +382,14 @@ func (p *bbbPWMPin) SetPeriod(ns int) error {
return fmt.Errorf("embd: pwm period for %v is out of bounds (must be =< %vns)", p.n, BBBPWMMaxPulseWidth)
}
_, err := p.period.WriteString(strconv.Itoa(ns))
return err
_, err := p.periodf.WriteString(strconv.Itoa(ns))
if err != nil {
return err
}
p.period = ns
return nil
}
func (p *bbbPWMPin) SetDuty(ns int) error {
@ -382,11 +398,35 @@ func (p *bbbPWMPin) SetDuty(ns int) error {
}
if ns > BBBPWMMaxPulseWidth {
return fmt.Errorf("embd: pwm duty for %v is out of bounds (must be =< %vns)", p.n, BBBPWMMaxPulseWidth)
return fmt.Errorf("embd: pwm duty %v for pin %v is out of bounds (must be =< %vns)", p.n, BBBPWMMaxPulseWidth)
}
_, err := p.duty.WriteString(strconv.Itoa(ns))
return err
if ns > p.period {
return fmt.Errorf("embd: pwm duty %v for pin %v is greater than the period %v", ns, p.n, p.period)
}
_, err := p.dutyf.WriteString(strconv.Itoa(ns))
if err != nil {
return err
}
return nil
}
func (p *bbbPWMPin) SetMicroseconds(us int) error {
if p.period != 20000000 {
glog.Warningf("embd: pwm pin %v has freq %v hz. recommended 50 hz for servo mode", 1000000000/p.period)
}
duty := us * 1000 // in nanoseconds
if duty > p.period {
return fmt.Errorf("embd: calculated pwm duty %vns for pin %v (servo mode) is greater than the period %vns", duty, p.n, p.period)
}
return p.SetDuty(duty)
}
func (p *bbbPWMPin) SetAnalog(value byte) error {
duty := util.Map(int64(value), 0, 255, 0, int64(p.period))
return p.SetDuty(int(duty))
}
func (p *bbbPWMPin) SetPolarity(pol Polarity) error {
@ -394,8 +434,14 @@ func (p *bbbPWMPin) SetPolarity(pol Polarity) error {
return err
}
_, err := p.polarity.WriteString(strconv.Itoa(int(pol)))
return err
_, err := p.polarityf.WriteString(strconv.Itoa(int(pol)))
if err != nil {
return err
}
p.polarity = pol
return nil
}
func (p *bbbPWMPin) reset() error {

36
controller/pca9685/pca9685.go
View File

@ -20,9 +20,7 @@ const (
pwm0OnLowReg = 0x6
minAnalogValue = 0
maxAnalogValue = 255
// inspired by arduino's default freq for analogWrites
defaultFreq = 490
)
@ -140,17 +138,35 @@ func (d *PCA9685) SetPwm(channel, onTime, offTime int) error {
return nil
}
// SetMicroseconds is a convinience method which allows easy servo control.
func (d *PCA9685) SetMicroseconds(channel, us int) error {
offTime := us * d.Freq * pwmControlPoints / 1000000
return d.SetPwm(channel, 0, offTime)
type pwmChannel struct {
d *PCA9685
channel int
}
func (p *pwmChannel) SetMicroseconds(us int) error {
return p.d.setMicroseconds(p.channel, us)
}
// SetAnalog is a convinience method which allows easy manipulation of the PWM
// based on a (0-255) range value.
func (d *PCA9685) SetAnalog(channel int, value byte) error {
offTime := util.Map(int64(value), minAnalogValue, maxAnalogValue, 0, pwmControlPoints-1)
return d.SetPwm(channel, 0, int(offTime))
func (p *pwmChannel) SetAnalog(value byte) error {
offTime := util.Map(int64(value), 0, 255, 0, pwmControlPoints-1)
return p.d.SetPwm(p.channel, 0, int(offTime))
}
func (d *PCA9685) ServoChannel(channel int) *pwmChannel {
return &pwmChannel{d: d, channel: channel}
}
func (d *PCA9685) AnalogChannel(channel int) *pwmChannel {
return &pwmChannel{d: d, channel: channel}
}
// SetMicroseconds is a convinience method which allows easy servo control.
func (d *PCA9685) setMicroseconds(channel, us int) error {
offTime := us * d.Freq * pwmControlPoints / 1000000
return d.SetPwm(channel, 0, offTime)
}
// Close stops the controller and resets mode and pwm controller registers.

16
controller/servoblaster/servoblaster.go
View File

@ -33,8 +33,22 @@ func (d *ServoBlaster) setup() error {
return nil
}
type pwmChannel struct {
d *ServoBlaster
channel int
}
func (p *pwmChannel) SetMicroseconds(us int) error {
return p.d.setMicroseconds(p.channel, us)
}
func (d *ServoBlaster) Channel(channel int) *pwmChannel {
return &pwmChannel{d: d, channel: channel}
}
// SetMicroseconds sends a command to the PWM driver to generate a us wide pulse.
func (d *ServoBlaster) SetMicroseconds(channel, us int) error {
func (d *ServoBlaster) setMicroseconds(channel, us int) error {
if err := d.setup(); err != nil {
return err
}

6
gpio.go
View File

@ -86,6 +86,12 @@ type PWMPin interface {
// SetPolarity sets the polarity of a pwm pin.
SetPolarity(pol Polarity) error
// SetMicroseconds sends a command to the PWM driver to generate a us wide pulse.
SetMicroseconds(us int) error
// SetAnalog allows easy manipulation of the PWM based on a (0-255) range value.
SetAnalog(value byte) error
// Close releases the resources associated with the pin.
Close() error
}

21
motion/servo/servo.go
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@ -11,25 +11,28 @@ const (
maxus = 2400
)
const (
// DefaultFreq represents the default (preferred) freq of a PWM doing servo duties.
DefaultFreq = 50
)
// A PWM interface implements access to a pwm controller.
type PWM interface {
SetMicroseconds(channel int, us int) error
SetMicroseconds(us int) error
}
type Servo struct {
PWM PWM
Channel int
PWM PWM
Minus, Maxus int
}
// New creates a new Servo interface.
func New(pwm PWM, channel int) *Servo {
func New(pwm PWM) *Servo {
return &Servo{
PWM: pwm,
Channel: channel,
Minus: minus,
Maxus: maxus,
PWM: pwm,
Minus: minus,
Maxus: maxus,
}
}
@ -39,5 +42,5 @@ func (s *Servo) SetAngle(angle int) error {
glog.V(1).Infof("servo: given angle %v calculated %v us", angle, us)
return s.PWM.SetMicroseconds(s.Channel, int(us))
return s.PWM.SetMicroseconds(int(us))
}

1
samples/.gitignore vendored
View File

@ -15,6 +15,7 @@ mcp4725
pca9685
pwm
servo
servobbb
servoblaster
tmp006
us020

10
samples/servo.go
View File

@ -20,11 +20,13 @@ func main() {
bus := embd.NewI2CBus(1)
pwm := pca9685.New(bus, 0x41)
pwm.Freq = 50
defer pwm.Close()
d := pca9685.New(bus, 0x41)
d.Freq = 50
defer d.Close()
servo := servo.New(pwm, 0)
pwm := d.ServoChannel(0)
servo := servo.New(pwm)
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt, os.Kill)

51
samples/servobbb.go Normal file
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@ -0,0 +1,51 @@
// +build ignore
package main
import (
"os"
"os/signal"
"time"
"github.com/kidoman/embd"
"github.com/kidoman/embd/motion/servo"
)
func main() {
embd.InitGPIO()
defer embd.CloseGPIO()
pwm, err := embd.NewPWMPin("P9_14")
if err != nil {
panic(err)
}
defer pwm.Close()
servo := servo.New(pwm)
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt, os.Kill)
turnTimer := time.Tick(500 * time.Millisecond)
left := true
servo.SetAngle(90)
defer func() {
servo.SetAngle(90)
}()
for {
select {
case <-turnTimer:
left = !left
switch left {
case true:
servo.SetAngle(70)
case false:
servo.SetAngle(110)
}
case <-c:
return
}
}
}

4
samples/servoblaster.go
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@ -15,7 +15,9 @@ func main() {
sb := servoblaster.New()
defer sb.Close()
servo := servo.New(sb, 0)
pwm := sb.Channel(0)
servo := servo.New(pwm)
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt, os.Kill)