diff --git a/_embdemo/hello-esp32/main.go b/_embdemo/hello-esp32/main.go
new file mode 100644
index 00000000..9b36080c
--- /dev/null
+++ b/_embdemo/hello-esp32/main.go
@@ -0,0 +1,16 @@
+package main
+
+import "github.com/goplus/lib/c"
+
+func myprint(s *c.Char) {
+	for i := 0; i < int(c.Strlen(s)); i++ {
+		WriteByte(byte(c.Index(s, i)))
+	}
+}
+
+func main() {
+	for {
+		myprint(c.Str("hello world"))
+		sleep(1)
+	}
+}
diff --git a/_embdemo/hello-esp32/uart.go b/_embdemo/hello-esp32/uart.go
new file mode 100644
index 00000000..1cd3a5ab
--- /dev/null
+++ b/_embdemo/hello-esp32/uart.go
@@ -0,0 +1,13 @@
+package main
+
+import (
+	_ "unsafe"
+
+	"github.com/goplus/lib/c"
+)
+
+//go:linkname WriteByte C.board_uart_write_char
+func WriteByte(b byte)
+
+//go:linkname sleep sleep
+func sleep(c c.Int)
diff --git a/_embdemo/hello/main.go b/_embdemo/hello/main.go
deleted file mode 100644
index 3cf6a208..00000000
--- a/_embdemo/hello/main.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package main
-
-func myprint(s string) {
-	for i := 0; i < len(s); i++ {
-		WriteByte(s[i])
-	}
-}
-
-func main() {
-	myprint("hello world")
-}
diff --git a/_embdemo/hello/uart.go b/_embdemo/hello/uart.go
deleted file mode 100644
index 682443fb..00000000
--- a/_embdemo/hello/uart.go
+++ /dev/null
@@ -1,4 +0,0 @@
-package main
-
-//go:linkname WriteByte C.board_uart_write_char
-func WriteByte(b byte)
diff --git a/_embdemo/write-esp32/main.go b/_embdemo/write-esp32/main.go
new file mode 100644
index 00000000..dd59a86c
--- /dev/null
+++ b/_embdemo/write-esp32/main.go
@@ -0,0 +1,12 @@
+package main
+
+import "github.com/goplus/lib/c"
+
+func main() {
+	buf := c.Malloc(6)
+	c.Memset(buf, 0, 6)
+	c.Strncpy((*c.Char)(buf), c.Str("abcde"), 5)
+
+	write(1, (*c.Char)(buf), 5)
+
+}