diff --git a/pcb/adapter.go b/pcb/adapter.go
index 6e332ac..058be87 100644
--- a/pcb/adapter.go
+++ b/pcb/adapter.go
@@ -1,8 +1,13 @@
 package pcb
 
-import "th7/ports"
+import (
+	"th7/pcb/led"
+	"th7/ports"
+)
 
 func NewAdapter(LED bool) (ports.PCBPort, error) {
 
-	return NewDummyAdapter(LED)
+	ledController := led.NewLEDController()
+
+	return NewDummyAdapter(LED, ledController)
 }
diff --git a/pcb/dummy.go b/pcb/dummy.go
index 9018f5e..991583f 100644
--- a/pcb/dummy.go
+++ b/pcb/dummy.go
@@ -3,50 +3,26 @@ package pcb
 import (
 	"fmt"
 	"th7/data/pcb"
+	"th7/pcb/led"
 )
 
 type DummyAdapter struct {
-	table   pcb.Table
-	led_on  bool
-	use_led bool
+	table         pcb.Table
+	use_led       bool
+	ledController *led.LEDController
 }
 
-func NewDummyAdapter(led bool) (*DummyAdapter, error) {
+func NewDummyAdapter(led bool, controller *led.LEDController) (*DummyAdapter, error) {
 	var adapter DummyAdapter
 
 	adapter.use_led = led
-	adapter.LED_Disable()
+	adapter.ledController = controller
+
+	adapter.ledController.Off()
+
 	return &adapter, nil
 }
 
-func (d *DummyAdapter) LED_Enable() {
-	if !d.use_led {
-		return
-	}
-	//....
-	d.led_on = true
-}
-
-func (d *DummyAdapter) LED_Disable() {
-	if !d.use_led {
-		return
-	}
-	// ...
-	d.led_on = false
-}
-
-func (d *DummyAdapter) LED_Toggle() {
-	if !d.use_led {
-		return
-	}
-
-	if d.led_on {
-		d.LED_Disable()
-	} else {
-		d.LED_Enable()
-	}
-}
-
 func (d *DummyAdapter) Deinit() error {
 	// turn LED off ..
 	fmt.Println("dummy pcb adapter deinit")
diff --git a/pcb/led/led.go b/pcb/led/led.go
new file mode 100644
index 0000000..fa82573
--- /dev/null
+++ b/pcb/led/led.go
@@ -0,0 +1,100 @@
+package led
+
+import (
+	"sync"
+	"time"
+)
+
+const (
+	DurationFlick = 40 * time.Millisecond
+)
+
+type LEDController struct {
+	led1 bool
+	led2 bool
+	mu1  sync.Mutex
+	mu2  sync.Mutex
+}
+
+func NewLEDController() *LEDController {
+
+	var controller LEDController
+	controller.led1 = false
+	controller.led2 = false
+
+	return &controller
+}
+
+// turn both off
+func (c *LEDController) Off() {
+
+	c.led1 = false
+	c.led2 = false
+
+	c.Disable1()
+	c.Disable2()
+}
+
+func (c *LEDController) Enable1() {
+
+	if c.led1 {
+		return
+	}
+
+	c.led1 = true
+
+	// gpio code to turn LED 1 on
+}
+
+func (c *LEDController) Enable2() {
+
+	if c.led2 {
+		return
+	}
+
+	c.led2 = true
+
+	// gpio code to turn LED 2 on
+}
+
+func (c *LEDController) Disable1() {
+
+	if !c.led1 {
+		return
+	}
+
+	c.led1 = false
+
+	// gpio code to turn LED 1 off
+}
+
+func (c *LEDController) Disable2() {
+
+	if !c.led2 {
+		return
+	}
+
+	c.led2 = false
+
+	// gpio code to turn LED 2 off
+}
+
+func (c *LEDController) Flick1() {
+	c.mu1.Lock()
+	defer c.mu1.Unlock()
+
+	// assume it is off
+	c.Enable1()
+	time.Sleep(DurationFlick)
+	c.Disable1()
+}
+
+func (c *LEDController) Flick2() {
+	c.mu2.Lock()
+	defer c.mu2.Unlock()
+
+	// assume it is off
+	c.Enable2()
+	time.Sleep(DurationFlick)
+	c.Disable2()
+}
diff --git a/ports/pcb.go b/ports/pcb.go
index 063358a..e77bbf8 100644
--- a/ports/pcb.go
+++ b/ports/pcb.go
@@ -10,7 +10,4 @@ type PCBPort interface {
 	GetTable() pcb.Table
 	ReadChannel(int) (float64, error)
 	ReadPCBTemp() (float64, error)
-	LED_Disable()
-	LED_Enable()
-	LED_Toggle()
 }