Add support for '8-step mode' to easystepper

Currently, easystepper driver supports only '4-step mode' (12-23-34-41) when energizing the coils
This does not work with all motors & drivers (e.g. 28BJY-48 & ULN2003)

This commit adds support for 8-step mode (1-12-2-23-3-34-4-41)

Note: this commit breaks backward source compatibility for the factory/constructor functions.

easystepper/easystepper.go

@@ -2,28 +2,76 @@
 package easystepper // import "tinygo.org/x/drivers/easystepper"
 
 import (
+	"errors"
 	"machine"
 	"time"
 )
 
+// StepMode determines the coil sequence used to perform a single step
+type StepMode uint8
+
+// Valid values for StepMode
+const (
+	// ModeFour uses a 'four step' coil sequence (12-23-34-41). This is the default (zero-value) mode
+	ModeFour StepMode = iota
+	// ModeEight uses an 'eight step' coil sequence (1-12-2-23-3-34-4-41)
+	ModeEight
+)
+
+// stepCount is a helper function to return the number of steps in a StepMode sequence
+func (sm StepMode) stepCount() uint {
+	switch sm {
+	default:
+		fallthrough
+	case ModeFour:
+		return 4
+	case ModeEight:
+		return 8
+	}
+}
+
+// DeviceConfig contains the configuration data for a single easystepper driver
+type DeviceConfig struct {
+	// Pin1 ... Pin4 determines the pins to configure and use for the device
+	Pin1, Pin2, Pin3, Pin4 machine.Pin
+	// StepCount is the number of steps required to perform a full revolution of the stepper motor
+	StepCount uint
+	// RPM determines the speed of the stepper motor in 'Revolutions per Minute'
+	RPM uint
+	// Mode determines the coil sequence used to perform a single step
+	Mode StepMode
+}
+
+// DualDeviceConfig contains the configuration data for a dual easystepper driver
+type DualDeviceConfig struct {
+	DeviceConfig
+	// Pin5 ... Pin8 determines the pins to configure and use for the second device
+	Pin5, Pin6, Pin7, Pin8 machine.Pin
+}
+
 // Device holds the pins and the delay between steps
 type Device struct {
 	pins       [4]machine.Pin
-	stepDelay  int32
+	stepDelay  time.Duration
 	stepNumber uint8
+	stepMode   StepMode
 }
 
 // DualDevice holds information for controlling 2 motors
 type DualDevice struct {
-	devices [2]Device
+	devices [2]*Device
 }
 
-// New returns a new easystepper driver given 4 pins, number of steps and rpm
+// New returns a new single easystepper driver given a DeviceConfig
-func New(pin1, pin2, pin3, pin4 machine.Pin, steps int32, rpm int32) Device {
+func New(config DeviceConfig) (*Device, error) {
-	return Device{
+	if config.StepCount == 0 || config.RPM == 0 {
-		pins:      [4]machine.Pin{pin1, pin2, pin3, pin4},
+		return nil, errors.New("config.StepCount and config.RPM must be > 0")
-		stepDelay: 60000000 / (steps * rpm),
 	}
+	return &Device{
+		pins:      [4]machine.Pin{config.Pin1, config.Pin2, config.Pin3, config.Pin4},
+		stepDelay: time.Second * 60 / time.Duration((config.StepCount * config.RPM)),
+		stepMode:  config.Mode,
+	}, nil
 }
 
 // Configure configures the pins of the Device
@@ -34,17 +82,23 @@ func (d *Device) Configure() {
 }
 
 // NewDual returns a new dual easystepper driver given 8 pins, number of steps and rpm
-func NewDual(pin1, pin2, pin3, pin4, pin5, pin6, pin7, pin8 machine.Pin, steps int32, rpm int32) DualDevice {
+func NewDual(config DualDeviceConfig) (*DualDevice, error) {
-	var dual DualDevice
+	// Create the first device
-	dual.devices[0] = Device{
+	dev1, err := New(config.DeviceConfig)
-		pins:      [4]machine.Pin{pin1, pin2, pin3, pin4},
+	if err != nil {
-		stepDelay: 60000000 / (steps * rpm),
+		return nil, err
 	}
-	dual.devices[1] = Device{
+	// Create the second device
-		pins:      [4]machine.Pin{pin5, pin6, pin7, pin8},
+	config.DeviceConfig.Pin1 = config.Pin5
-		stepDelay: 60000000 / (steps * rpm),
+	config.DeviceConfig.Pin2 = config.Pin6
+	config.DeviceConfig.Pin3 = config.Pin7
+	config.DeviceConfig.Pin4 = config.Pin8
+	dev2, err := New(config.DeviceConfig)
+	if err != nil {
+		return nil, err
 	}
-	return dual
+	// Return composite dual device
+	return &DualDevice{devices: [2]*Device{dev1, dev2}}, nil
 }
 
 // Configure configures the pins of the DualDevice
@@ -64,7 +118,7 @@ func (d *Device) Move(steps int32) {
 	var s int32
 	d.stepMotor(d.stepNumber)
 	for s = int32(d.stepNumber); s < steps; s++ {
-		time.Sleep(time.Duration(d.stepDelay) * time.Microsecond)
+		time.Sleep(d.stepDelay)
 		d.moveDirectionSteps(direction, s)
 	}
 }
@@ -101,7 +155,7 @@ func (d *DualDevice) Move(stepsA, stepsB int32) {
 	stepsA += int32(d.devices[max].stepNumber)
 	minStep = int32(d.devices[min].stepNumber)
 	for s := int32(d.devices[max].stepNumber); s < stepsA; s++ {
-		time.Sleep(time.Duration(d.devices[0].stepDelay) * time.Microsecond)
+		time.Sleep(d.devices[0].stepDelay)
 		d.devices[max].moveDirectionSteps(directions[max], s)
 
 		if ((s * stepsB) / stepsA) > minStep {
@@ -119,6 +173,18 @@ func (d *DualDevice) Off() {
 
 // stepMotor changes the pins' state to the correct step
 func (d *Device) stepMotor(step uint8) {
+	switch d.stepMode {
+	default:
+		fallthrough
+	case ModeFour:
+		d.stepMotor4(step)
+	case ModeEight:
+		d.stepMotor8(step)
+	}
+}
+
+// stepMotor4 changes the pins' state to the correct step in 4-step mode
+func (d *Device) stepMotor4(step uint8) {
 	switch step {
 	case 0:
 		d.pins[0].High()
@@ -148,13 +214,63 @@ func (d *Device) stepMotor(step uint8) {
 	d.stepNumber = step
 }
 
+// stepMotor8 changes the pins' state to the correct step in 8-step mode
+func (d *Device) stepMotor8(step uint8) {
+	switch step {
+	case 0:
+		d.pins[0].High()
+		d.pins[2].Low()
+		d.pins[1].Low()
+		d.pins[3].Low()
+	case 1:
+		d.pins[0].High()
+		d.pins[2].High()
+		d.pins[1].Low()
+		d.pins[3].Low()
+	case 2:
+		d.pins[0].Low()
+		d.pins[2].High()
+		d.pins[1].Low()
+		d.pins[3].Low()
+	case 3:
+		d.pins[0].Low()
+		d.pins[2].High()
+		d.pins[1].High()
+		d.pins[3].Low()
+	case 4:
+		d.pins[0].Low()
+		d.pins[2].Low()
+		d.pins[1].High()
+		d.pins[3].Low()
+	case 5:
+		d.pins[0].Low()
+		d.pins[2].Low()
+		d.pins[1].High()
+		d.pins[3].High()
+	case 6:
+		d.pins[0].Low()
+		d.pins[2].Low()
+		d.pins[1].Low()
+		d.pins[3].High()
+	case 7:
+		d.pins[0].High()
+		d.pins[2].Low()
+		d.pins[1].Low()
+		d.pins[3].High()
+	}
+	d.stepNumber = step
+}
+
 // moveDirectionSteps uses the direction to calculate the correct step and change the motor to it.
-// Direction true: 0, 1, 2, 3, 0, 1, 2, ...
+// Direction true:  (4-step mode) 0, 1, 2, 3, 0, 1, 2, ...
-// Direction false: 0, 3, 2, 1, 0, 3, 2, ...
+// Direction false: (4-step mode) 0, 3, 2, 1, 0, 3, 2, ...
+// Direction true:  (8-step mode) 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, ...
+// Direction false: (8-step mode) 0, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, ...
 func (d *Device) moveDirectionSteps(direction bool, step int32) {
+	modulus := int32(d.stepMode.stepCount())
 	if direction {
-		d.stepMotor(uint8(step % 4))
+		d.stepMotor(uint8(step % modulus))
 	} else {
-		d.stepMotor(uint8((step + 2*(step%2)) % 4))
+		d.stepMotor(uint8(((-step % modulus) + modulus) % modulus))
 	}
 }

examples/easystepper/main.go

@@ -8,7 +8,11 @@ import (
 )
 
 func main() {
-	motor := easystepper.New(machine.P13, machine.P15, machine.P14, machine.P16, 200, 75)
+	config := easystepper.DeviceConfig{
+		Pin1: machine.P13, Pin2: machine.P15, Pin3: machine.P14, Pin4: machine.P16,
+		StepCount: 200, RPM: 75, Mode: easystepper.ModeFour,
+	}
+	motor, _ := easystepper.New(config)
 	motor.Configure()
 
 	for {