diff --git a/app/uart_stdout.h b/app/uart_stdout.h
new file mode 100644
index 0000000..7c69c71
--- /dev/null
+++ b/app/uart_stdout.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2019, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#ifndef __UART_STDOUT_H__
+#define __UART_STDOUT_H__
+
+#include <stdint.h>
+
+/**
+ * \brief Output buffer by STDIO.
+ */
+int stdio_output_string(const unsigned char *str, uint32_t len);
+
+#endif /* __UART_STDOUT_H__ */