diff --git a/hal/driver.go b/hal/driver.go
index d5ebfa0..6c5c86a 100644
--- a/hal/driver.go
+++ b/hal/driver.go
@@ -2,6 +2,7 @@ package hal
 
 import (
 	"fmt"
+	"sort"
 
 	"github.com/reef-pi/hal"
 	"github.com/reef-pi/rpi/pwm"
@@ -45,3 +46,37 @@ func (d *driver) Pins(cap hal.Capability) ([]hal.Pin, error) {
 		return nil, fmt.Errorf("Unsupported capability:%s", cap.String())
 	}
 }
+
+func (r *driver) DigitalInputPins() []hal.DigitalInputPin {
+	var pins []hal.DigitalInputPin
+	for _, pin := range r.pins {
+		pins = append(pins, pin)
+	}
+	sort.Slice(pins, func(i, j int) bool { return pins[i].Name() < pins[j].Name() })
+	return pins
+}
+
+func (r *driver) DigitalInputPin(p int) (hal.DigitalInputPin, error) {
+	pin, ok := r.pins[p]
+	if !ok {
+		return nil, fmt.Errorf("pin %d unknown", p)
+	}
+	return pin, nil
+}
+
+func (r *driver) DigitalOutputPins() []hal.DigitalOutputPin {
+	var pins []hal.DigitalOutputPin
+	for _, pin := range r.pins {
+		pins = append(pins, pin)
+	}
+	sort.Slice(pins, func(i, j int) bool { return pins[i].Name() < pins[j].Name() })
+	return pins
+}
+
+func (r *driver) DigitalOutputPin(p int) (hal.DigitalOutputPin, error) {
+	pin, ok := r.pins[p]
+	if !ok {
+		return nil, fmt.Errorf("pin %d unknown", p)
+	}
+	return pin, nil
+}
diff --git a/hal/factory.go b/hal/factory.go
index 9423d86..2dc60f9 100644
--- a/hal/factory.go
+++ b/hal/factory.go
@@ -90,7 +90,7 @@ func (f *rpiFactory) Metadata() hal.Metadata {
 	return f.meta
 }
 
-func (f *rpiFactory) NewDriver(parameters map[string]interface{}, hardwareResources interface{}) (hal.Driver, error) {
+func (f *rpiFactory) NewDriver(parameters map[string]interface{}, _ interface{}) (hal.Driver, error) {
 	if valid, failures := f.ValidateParameters(parameters); !valid {
 		return nil, errors.New(hal.ToErrorString(failures))
 	}
diff --git a/hal/gpio.go b/hal/gpio.go
deleted file mode 100644
index 82e9a34..0000000
--- a/hal/gpio.go
+++ /dev/null
@@ -1,116 +0,0 @@
-package hal
-
-import (
-	"fmt"
-	"sort"
-
-	"github.com/reef-pi/hal"
-)
-
-var (
-	validGPIOPins = map[int]bool{
-		2:  true,
-		3:  true,
-		4:  true,
-		5:  true,
-		6:  true,
-		7:  true,
-		8:  true,
-		9:  true,
-		10: true,
-		11: true,
-		12: true,
-		13: true,
-		14: true,
-		15: true,
-		16: true,
-		17: true,
-		18: true,
-		19: true,
-		20: true,
-		21: true,
-		22: true,
-		23: true,
-		24: true,
-		25: true,
-		26: true,
-		27: true,
-	}
-)
-
-type pin struct {
-	number    int
-	name      string
-	lastState bool
-
-	digitalPin DigitalPin
-}
-
-func (p *pin) Name() string {
-	return p.name
-}
-func (p *pin) Number() int {
-	return p.number
-}
-
-func (p *pin) Close() error {
-	return p.digitalPin.Close()
-}
-
-func (p *pin) Read() (bool, error) {
-	if err := p.digitalPin.SetDirection(false); err != nil {
-		return false, fmt.Errorf("can't read input from pin %d: %v", p.number, err)
-	}
-	v, err := p.digitalPin.Read()
-	return v == 1, err
-}
-
-func (p *pin) Write(state bool) error {
-	if err := p.digitalPin.SetDirection(true); err != nil {
-		return fmt.Errorf("can't set output on pin %d: %v", p.number, err)
-	}
-	value := 0
-	if state {
-		value = 1
-	}
-	p.lastState = state
-	return p.digitalPin.Write(value)
-}
-
-func (p *pin) LastState() bool {
-	return p.lastState
-}
-
-func (r *driver) DigitalInputPins() []hal.DigitalInputPin {
-	var pins []hal.DigitalInputPin
-	for _, pin := range r.pins {
-		pins = append(pins, pin)
-	}
-	sort.Slice(pins, func(i, j int) bool { return pins[i].Name() < pins[j].Name() })
-	return pins
-}
-
-func (r *driver) DigitalInputPin(p int) (hal.DigitalInputPin, error) {
-	pin, ok := r.pins[p]
-	if !ok {
-		return nil, fmt.Errorf("pin %d unknown", p)
-	}
-	return pin, nil
-}
-
-func (r *driver) DigitalOutputPins() []hal.DigitalOutputPin {
-	var pins []hal.DigitalOutputPin
-	for _, pin := range r.pins {
-		pins = append(pins, pin)
-	}
-	sort.Slice(pins, func(i, j int) bool { return pins[i].Name() < pins[j].Name() })
-	return pins
-}
-
-func (r *driver) DigitalOutputPin(p int) (hal.DigitalOutputPin, error) {
-	pin, ok := r.pins[p]
-	if !ok {
-		return nil, fmt.Errorf("pin %d unknown", p)
-	}
-	return pin, nil
-}
diff --git a/hal/pin.go b/hal/pin.go
new file mode 100644
index 0000000..bbe1166
--- /dev/null
+++ b/hal/pin.go
@@ -0,0 +1,46 @@
+package hal
+
+import "fmt"
+
+type pin struct {
+	number    int
+	name      string
+	lastState bool
+
+	digitalPin DigitalPin
+}
+
+func (p *pin) Name() string {
+	return p.name
+}
+func (p *pin) Number() int {
+	return p.number
+}
+
+func (p *pin) Close() error {
+	return p.digitalPin.Close()
+}
+
+func (p *pin) Read() (bool, error) {
+	if err := p.digitalPin.SetDirection(false); err != nil {
+		return false, fmt.Errorf("can't read input from pin %d: %v", p.number, err)
+	}
+	v, err := p.digitalPin.Read()
+	return v == 1, err
+}
+
+func (p *pin) Write(state bool) error {
+	if err := p.digitalPin.SetDirection(true); err != nil {
+		return fmt.Errorf("can't set output on pin %d: %v", p.number, err)
+	}
+	value := 0
+	if state {
+		value = 1
+	}
+	p.lastState = state
+	return p.digitalPin.Write(value)
+}
+
+func (p *pin) LastState() bool {
+	return p.lastState
+}
diff --git a/hal/valid_gpio_pins.go b/hal/valid_gpio_pins.go
new file mode 100644
index 0000000..aed7e60
--- /dev/null
+++ b/hal/valid_gpio_pins.go
@@ -0,0 +1,32 @@
+package hal
+
+var (
+	validGPIOPins = map[int]bool{
+		2:  true,
+		3:  true,
+		4:  true,
+		5:  true,
+		6:  true,
+		7:  true,
+		8:  true,
+		9:  true,
+		10: true,
+		11: true,
+		12: true,
+		13: true,
+		14: true,
+		15: true,
+		16: true,
+		17: true,
+		18: true,
+		19: true,
+		20: true,
+		21: true,
+		22: true,
+		23: true,
+		24: true,
+		25: true,
+		26: true,
+		27: true,
+	}
+)