diff --git a/Makefile b/Makefile
index da26c98..d010152 100644
--- a/Makefile
+++ b/Makefile
@@ -20,6 +20,8 @@ smoketest:
 	go build -o /tmp/test ./xiao-ble/ble-led-client
 	tinygo build -o /tmp/test.hex --target xiao-ble --size short ./xiao-ble/ble-led-client
 	tinygo build -o /tmp/test.hex --target xiao-ble --size short ./xiao-ble/ble-led-client-xiao
+	tinygo build -o /tmp/test.hex --target xiao-ble --size short ./xiao-ble-laptimer/laptimer-xiao
+	go build -o /tmp/test ./xiao-ble-laptimer/laptimer
 
 fmt-check:
 	@unformatted=$$(gofmt -l `find . -name "*.go"`); [ -z "$$unformatted" ] && exit 0; echo "Unformatted:"; for fn in $$unformatted; do echo "  $$fn"; done; exit 1
diff --git a/README.md b/README.md
index 35e9228..1188413 100644
--- a/README.md
+++ b/README.md
@@ -44,6 +44,10 @@ This is a Demo using Bluetooth.
 
 [![](https://img.youtube.com/vi/HWBxuMbNUTI/0.jpg)](https://www.youtube.com/watch?v=HWBxuMbNUTI)
 
+* [./xiao-ble-laptimer/](./xiao-ble-laptimer/)
+
+![](./xiao-ble-laptimer/xiao-ble-laptimer.jpg)
+
 
 
 ## wioterminal initialize
diff --git a/xiao-ble-laptimer/README.md b/xiao-ble-laptimer/README.md
new file mode 100644
index 0000000..c442aec
--- /dev/null
+++ b/xiao-ble-laptimer/README.md
@@ -0,0 +1,50 @@
+# xiao-ble-laptimer examples
+
+TinyGo example of XIAO BLE.  
+This is a Demo using Bluetooth.
+
+* [./xiao-ble-laptimer/laptimer/](./ble-laptimer/laptimer/)
+* [./xiao-ble-laptimer/laptimer-xiao/](./laptimer-xiao/)
+
+![](./xiao-ble-laptimer.jpg)
+
+
+## Usage
+
+First flash it to an nRF52840 microcontroller such as xiao-ble.  
+
+```
+$ tinygo flash --target xiao-ble --size short ./xiao-ble-laptimer/laptimer-xiao
+   code    data     bss |   flash     ram
+  11228     156    8012 |   11384    8168
+```
+
+Then, start a program to measure the lap time on the computer.  
+If the BLE scan fails for 3 minutes, the next lap is considered to have progressed.  
+
+
+```
+$ go run ./xiao-ble-laptimer/laptimer
+```
+
+To change to a value other than 3 minutes, change the following settings.  
+
+
+```go
+	thresh := 3 * time.Minute
+```
+
+Below is the actual log file.  
+
+```
+2022/10/22 10:46:25 2562047:47:16 0 found
+2022/10/22 10:53:06 lost
+2022/10/22 11:26:39 00:40:14 1 found
+2022/10/22 11:30:02 lost
+2022/10/22 11:38:02 00:11:23 2 found
+2022/10/22 11:41:19 lost
+2022/10/22 11:48:16 00:10:13 3 found
+2022/10/22 11:51:31 lost
+2022/10/22 11:58:43 00:10:26 4 found
+2022/10/22 12:01:58 lost
+```
diff --git a/xiao-ble-laptimer/laptimer-xiao/main.go b/xiao-ble-laptimer/laptimer-xiao/main.go
new file mode 100644
index 0000000..abcfedd
--- /dev/null
+++ b/xiao-ble-laptimer/laptimer-xiao/main.go
@@ -0,0 +1,55 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/bluetooth"
+)
+
+var adapter = bluetooth.DefaultAdapter
+var ledColor = []byte{0x00, 0x00, 0x00, 0x00}
+
+var (
+	serviceUUID = bluetooth.NewUUID([16]byte{0xa0, 0xb4, 0x00, 0x01, 0x92, 0x6d, 0x4d, 0x61, 0x98, 0xdf, 0x8c, 0x5c, 0x62, 0xee, 0x53, 0xb3})
+	charUUID    = bluetooth.NewUUID([16]byte{0xa0, 0xb4, 0x00, 0x02, 0x92, 0x6d, 0x4d, 0x61, 0x98, 0xdf, 0x8c, 0x5c, 0x62, 0xee, 0x53, 0xb3})
+)
+
+func main() {
+	println("starting")
+	must("enable BLE stack", adapter.Enable())
+	adv := adapter.DefaultAdvertisement()
+	must("config adv", adv.Configure(bluetooth.AdvertisementOptions{
+		LocalName: "No 10 - TinyGo LapTimer",
+		Interval:  bluetooth.NewDuration(32 * time.Millisecond),
+	}))
+	must("start adv", adv.Start())
+
+	led := machine.LED
+	led.Configure(machine.PinConfig{Mode: machine.PinOutput})
+
+	//var err error
+	for {
+		//fmt.Printf("start\r\n")
+		//err = adv.Start()
+		//if err != nil {
+		//	fmt.Printf("err %s\r\n", err.Error())
+		//}
+
+		led.Low()
+		time.Sleep(time.Millisecond * 100)
+		led.High()
+		time.Sleep(time.Millisecond * 100)
+		//fmt.Printf("stop\r\n")
+		//err = adv.Stop()
+		//if err != nil {
+		//	fmt.Printf("err %s\r\n", err.Error())
+		//}
+	}
+}
+
+func must(action string, err error) {
+	if err != nil {
+		panic("failed to " + action + ": " + err.Error())
+	}
+}
diff --git a/xiao-ble-laptimer/laptimer/main.go b/xiao-ble-laptimer/laptimer/main.go
new file mode 100644
index 0000000..2ebec28
--- /dev/null
+++ b/xiao-ble-laptimer/laptimer/main.go
@@ -0,0 +1,151 @@
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	"tinygo.org/x/bluetooth"
+)
+
+// bluetooth
+var (
+	adapter     = bluetooth.DefaultAdapter
+	dc          bluetooth.DeviceCharacteristic
+	serviceUUID = bluetooth.NewUUID([16]byte{0xa0, 0xb4, 0x00, 0x01, 0x92, 0x6d, 0x4d, 0x61, 0x98, 0xdf, 0x8c, 0x5c, 0x62, 0xee, 0x53, 0xb3})
+	charUUID    = bluetooth.NewUUID([16]byte{0xa0, 0xb4, 0x00, 0x02, 0x92, 0x6d, 0x4d, 0x61, 0x98, 0xdf, 0x8c, 0x5c, 0x62, 0xee, 0x53, 0xb3})
+)
+
+func getCurrentStatus(file string) (bool, time.Time, int, error) {
+	//time.Local = time.FixedZone("Asia/Tokyo", 9*60*60)
+	found := false
+	var prevTimeOfLap time.Time
+	laps := 0
+
+	r, err := os.Open(file)
+	if err != nil {
+		return found, prevTimeOfLap, laps, err
+	}
+	defer r.Close()
+
+	scanner := bufio.NewScanner(r)
+	lastLine := ""
+	lastLineWithFound := ""
+	for scanner.Scan() {
+		lastLine = scanner.Text()
+		fmt.Printf("%s\n", lastLine)
+		if strings.HasSuffix(lastLine, " found") {
+			lastLineWithFound = lastLine
+			found = true
+		} else {
+			found = false
+		}
+	}
+
+	prevTimeOfLap, err = time.Parse("2006/01/02 15:04:05", lastLineWithFound[:19])
+	if err == nil {
+		prevTimeOfLap = prevTimeOfLap.Add(-1 * 9 * time.Hour)
+	}
+
+	spl := strings.Split(lastLineWithFound, " ")
+	x, _ := strconv.ParseUint(spl[3], 10, 64)
+	laps = int(x) + 1
+	//fmt.Printf("prev : %s\n", prevTimeOfLap.In(time.Local))
+	//fmt.Printf("%s\n", lastLineWithFound)
+
+	return found, prevTimeOfLap, laps, nil
+}
+
+func run() error {
+	found, prevTimeOfLap, laps, err := getCurrentStatus("data.txt")
+	if err != nil {
+		//return err
+	}
+
+	wfh, err := os.OpenFile("data.txt", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0666)
+	if err != nil {
+		return err
+	}
+	defer wfh.Close()
+
+	w := io.MultiWriter(os.Stdout, wfh)
+	log.SetOutput(w)
+
+	must("enable BLE stack", adapter.Enable())
+
+	// Scan for NUS peripheral.
+	timeFromLastFound := time.Now()
+	//thresh := 1 * time.Second
+	thresh := 3 * time.Minute
+	if debug {
+		thresh = 1000 * time.Millisecond
+	}
+	// found -> lost の間は thresh 以上の時間が必要
+	// 逆に lost -> found の間も thresh 以上の時間が必要
+	for {
+		cont := true
+		//println("scanning")
+		for cont {
+			err := adapter.Scan(func(adapter *bluetooth.Adapter, result bluetooth.ScanResult) {
+				//fmt.Printf("%#v\n", result.Address.String())
+				//fmt.Printf("%#v %d\n", result.Address.String(), -1*time.Until(timer))
+				if result.LocalName() != "No 10 - TinyGo LapTimer" {
+					if -1*time.Until(timeFromLastFound) > thresh {
+						if found {
+							log.Printf("lost")
+							//time.Sleep(thresh)
+						}
+						found = false
+					}
+					return
+				}
+
+				// Stop the scan.
+				err := adapter.StopScan()
+				if err != nil {
+					// Unlikely, but we can't recover from this.
+					println("failed to stop the scan:", err.Error())
+				}
+			})
+			if err != nil {
+				println("could not start a scan:", err.Error())
+				return err
+			} else {
+				if !found {
+					lapTime := int(time.Now().Sub(prevTimeOfLap).Seconds())
+					log.Printf("%02d:%02d:%02d %d found", lapTime/3600, (lapTime/60)%60, lapTime%60, laps)
+					laps++
+					prevTimeOfLap = time.Now()
+				}
+				found = true
+				timeFromLastFound = time.Now()
+				cont = false
+			}
+		}
+	}
+	return nil
+}
+
+var debug bool
+
+func main() {
+	flag.BoolVar(&debug, "debug", debug, "debug")
+	flag.Parse()
+
+	err := run()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func must(action string, err error) {
+	if err != nil {
+		panic("failed to " + action + ": " + err.Error())
+	}
+}
diff --git a/xiao-ble-laptimer/xiao-ble-laptimer.jpg b/xiao-ble-laptimer/xiao-ble-laptimer.jpg
new file mode 100644
index 0000000..f5ccd91
Binary files /dev/null and b/xiao-ble-laptimer/xiao-ble-laptimer.jpg differ