robocar-pca9685/pkg/actuator/pca9685.go

package actuator

import (
	"fmt"
	"github.com/cyrilix/robocar-pca9685/pkg/util"
	"go.uber.org/zap"
	"periph.io/x/conn/v3/gpio"
	"periph.io/x/conn/v3/i2c/i2creg"
	"periph.io/x/conn/v3/physic"
	"periph.io/x/devices/v3/pca9685"
	"periph.io/x/host/v3"
)

const (
	MinPercent = -1.
	MaxPercent = 1.
)

type PWM int

func NewDevice(freq physic.Frequency) *pca9685.Dev {
	zap.S().Info("NewDevice pca9685 controller")
	_, err := host.Init()
	if err != nil {
		zap.S().Fatalf("unable to NewDevice host: %v", err)
	}

	zap.S().Info("open i2c bus")
	bus, err := i2creg.Open("")
	if err != nil {
		zap.S().Fatalf("unable to NewDevice i2c bus: %v", err)
	}
	zap.S().Infof("i2c bus opened: %v", bus)

	device, err := pca9685.NewI2C(bus, pca9685.I2CAddr)
	if err != nil {
		zap.S().Fatalf("unable to NewDevice pca9685 bus: %v", err)
	}
	zap.S().Infof("set pwm frequency to %v", freq)
	err = device.SetPwmFreq(freq)
	if err != nil {
		zap.S().Panicf("unable to set pwm frequency: %v", err)
	}
	zap.S().Info("NewDevice done")
	return device
}

func (c *Pca9685Controller) convertToDuty(percent float32) (gpio.Duty, error) {
	// map absolute angle to angle that vehicle can implement.
	pw := int(c.neutralPWM)
	if percent > 0 {
		pw = util.MapRange(float64(percent), 0, c.maxPercent, float64(c.neutralPWM), float64(c.maxPWM))
	} else if percent < 0 {
		pw = util.MapRange(float64(percent), c.minPercent, 0, float64(c.minPWM), float64(c.neutralPWM))
	}
	c.logr.Debugf("convert value %v to pw: %v", percent, pw)

	per := c.freq.Period().Microseconds()

	draw := float64(pw) / float64(per)
	return gpio.Duty(int32(draw * float64(gpio.DutyMax))), nil
}

type Pca9685Controller struct {
	logr                       *zap.SugaredLogger
	pin                        gpio.PinIO
	minPWM, maxPWM, neutralPWM PWM
	minPercent, maxPercent     float64
	freq                       physic.Frequency
}

func (c *Pca9685Controller) Close() error {
	return c.pin.Halt()
}

func (c *Pca9685Controller) SetDuty(d gpio.Duty) error {
	c.logr.Debugf("set duty %v -> %d (12bits value: %d)", d.String(), d, d>>12)

	err := c.pin.PWM(d, c.freq)
	if err != nil {
		return fmt.Errorf("unable to set pwm value: %v", err)
	}
	return nil
}

// SetPercentValue Set percent value
func (c *Pca9685Controller) SetPercentValue(p float32) error {
	d, err := c.convertToDuty(p)
	if err != nil {
		return fmt.Errorf("unable to compute Duty value for steering: %w", err)
	}
	err = c.SetDuty(d)
	if err != nil {
		return fmt.Errorf("unable to apply duty value '%v' for pin '%v': '%w' ", d, c.pin.Name(), err)
	}
	return nil
}

func NewPca9685Controller(device *pca9685.Dev, channel int, minPWM, maxPWM, neutralPWM PWM, minPercent, maxPercent float64,
	freq physic.Frequency, logr *zap.SugaredLogger) (*Pca9685Controller, error) {
	p, err := device.CreatePin(channel)
	if err != nil {
		return nil, fmt.Errorf("unable to create pin for channel %v: %w", channel, err)
	}
	s := Pca9685Controller{
		pin:        p,
		minPWM:     minPWM,
		maxPWM:     maxPWM,
		neutralPWM: neutralPWM,
		minPercent: minPercent,
		maxPercent: maxPercent,
		freq:       freq,
		logr:       logr,
	}
	return &s, nil
}