Add driver support for cd74hc4067

[scriptchildie]

Add support for cd74hc4067 https://www.sparkfun.com/datasheets/IC/CD74HC4067.pdf

Driver Code:

import (
	"fmt"
	"machine"
)

type Device struct {
	s0, s1, s2, s3, en machine.Pin
	sigADC             machine.ADC
}

// Returns a new Multiplex driver
func New(s0Pin, s1Pin, s2Pin, s3Pin, enPin machine.Pin, sigAdcPin machine.Pin) Device {
	return Device{
		s0: s0Pin,
		s1: s1Pin,
		s2: s2Pin,
		s3: s3Pin,
		en: enPin,
		sigADC: machine.ADC{
			sigAdcPin,
		},
	}
}

// Configure configures the Device.
func (d *Device) Configure() {
	d.s0.Configure(machine.PinConfig{Mode: machine.PinOutput})
	d.s1.Configure(machine.PinConfig{Mode: machine.PinOutput})
	d.s2.Configure(machine.PinConfig{Mode: machine.PinOutput})
	d.s3.Configure(machine.PinConfig{Mode: machine.PinOutput})
	d.en.Configure(machine.PinConfig{Mode: machine.PinOutput})

	machine.InitADC()
	d.sigADC.Configure(machine.ADCConfig{})

}

// Read ADC value from specific PIN
func (d *Device) ReadValue(pin int8) (uint16, error) {

	if pin > 15 {
		return 0, fmt.Errorf("Valid Input Values are 0-15")
	}
	binSlice := int8ToBoolSlice(pin)

	d.en.Low() // enabled on low
	d.s0.Set(binSlice[7])
	d.s1.Set(binSlice[6])
	d.s2.Set(binSlice[5])
	d.s3.Set(binSlice[4])

	return d.sigADC.Get(), nil
}

// Read all values and return a slice
func (d *Device) ReadAll() [16]uint16 {
	var result [16]uint16

	for i := 0; i < 16; i++ {
		result[i], _ = d.ReadValue(int8(i))
	}
	return result
}

// Select Channel None
func (d *Device) Disable() {
	d.en.High()
}

// Internal function to convert
// intiger to a binary slice to use
// in the ReadValue
func int8ToBoolSlice(num int8) [8]bool {
	var result [8]bool
	for i := 0; i < 8; i++ {
		bit := (num >> i) & 1
		result[7-i] = bit != 0
	}
	return result
}

Example Code:

import (
	"fmt"
	"machine"
	"time"

	"embedded/cd74hc4067"
)

func main() {
	mux := cd74hc4067.New(machine.GP21, machine.GP20, machine.GP19, machine.GP18, machine.GP22, machine.ADC0)
	mux.Configure()
	for {
		time.Sleep(2 * time.Second)
		fmt.Println(mux.ReadAll())

		val, _ := mux.ReadValue(0)
		fmt.Println(val)

	}

}