diff --git a/firmware/libcommon/include/stdio.h b/firmware/libcommon/include/stdio.h
index 7695d20..258c7ab 100644
--- a/firmware/libcommon/include/stdio.h
+++ b/firmware/libcommon/include/stdio.h
@@ -52,9 +52,14 @@
 signed int sprintf(char *pStr, const char *pFormat, ...);
 signed int puts(const char *pStr);
 
-
 int fputc(int c, FILE *stream);
 int fputs(const char *s, FILE *stream);
 
 #define putc(c, stream) fputc(c, stream)
 #define putchar(c) fputc(c, stdout)
+
+signed int vfprintf_sync(FILE *pStream, const char *pFormat, va_list ap);
+signed int vprintf_sync(const char *pFormat, va_list ap);
+signed int printf_sync(const char *pFormat, ...);
+int fputc_sync(int c, FILE *stream);
+int fputs_sync(const char *s, FILE *stream);
diff --git a/firmware/libcommon/source/fputs.c b/firmware/libcommon/source/fputs.c
index ca6f851..110f68e 100644
--- a/firmware/libcommon/source/fputs.c
+++ b/firmware/libcommon/source/fputs.c
@@ -26,6 +26,19 @@
 int fputs(const char *s, FILE *stream)
 {
 	while (*s != '\0')
-		UART_PutChar(*s++);
+		fputc(*s++, stream);
+	return 0;
+}
+
+int fputc_sync(int c, FILE *stream)
+{
+	UART_PutChar_Sync(c);
+	return c;
+}
+
+int fputs_sync(const char *s, FILE *stream)
+{
+	while (*s != '\0')
+		fputc_sync(*s++, stream);
 	return 0;
 }
diff --git a/firmware/libcommon/source/stdio.c b/firmware/libcommon/source/stdio.c
index 505c895..06ad611 100644
--- a/firmware/libcommon/source/stdio.c
+++ b/firmware/libcommon/source/stdio.c
@@ -2,6 +2,7 @@
  *         ATMEL Microcontroller Software Support 
  * ----------------------------------------------------------------------------
  * Copyright (c) 2008, Atmel Corporation
+ * Copyright (c) 2018, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
  *
  * All rights reserved.
  *
@@ -436,6 +437,32 @@
 }
 
 //------------------------------------------------------------------------------
+/// Outputs a formatted string on the given stream. Format arguments are given
+/// in a va_list instance.
+/// \note This function is synchronous (i.e. blocks until the print completes)
+/// \param pStream  Output stream.
+/// \param pFormat  Format string
+/// \param ap  Argument list.
+//------------------------------------------------------------------------------
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
+signed int vfprintf_sync(FILE *pStream, const char *pFormat, va_list ap)
+{
+	char pStr[MAX_STRING_SIZE];
+	char pError[] = "stdio.c: increase MAX_STRING_SIZE\n\r";
+
+	// Write formatted string in buffer
+	if (vsprintf(pStr, pFormat, ap) >= MAX_STRING_SIZE) {
+
+		fputs_sync(pError, stderr);
+	}
+
+	// Display string
+	return fputs_sync(pStr, pStream);
+}
+#pragma GCC diagnostic pop
+
+//------------------------------------------------------------------------------
 /// Outputs a formatted string on the DBGU stream. Format arguments are given
 /// in a va_list instance.
 /// \param pFormat  Format string
@@ -447,6 +474,18 @@
 }
 
 //------------------------------------------------------------------------------
+/// Outputs a formatted string on the DBGU stream. Format arguments are given
+/// in a va_list instance.
+/// \note This function is synchronous (i.e. blocks until the print completes)
+/// \param pFormat  Format string
+/// \param ap  Argument list.
+//------------------------------------------------------------------------------
+signed int vprintf_sync(const char *pFormat, va_list ap)
+{
+	return vfprintf_sync(stdout, pFormat, ap);
+}
+
+//------------------------------------------------------------------------------
 /// Outputs a formatted string on the given stream, using a variable number of
 /// arguments.
 /// \param pStream  Output stream.
@@ -484,6 +523,25 @@
 }
 
 //------------------------------------------------------------------------------
+/// Outputs a formatted string on the DBGU stream, using a variable number of
+/// arguments.
+/// \note This function is synchronous (i.e. blocks until the print completes)
+/// \param pFormat  Format string.
+//------------------------------------------------------------------------------
+signed int printf_sync(const char *pFormat, ...)
+{
+	va_list ap;
+	signed int result;
+
+	// Forward call to vprintf
+	va_start(ap, pFormat);
+	result = vprintf_sync(pFormat, ap);
+	va_end(ap);
+
+	return result;
+}
+
+//------------------------------------------------------------------------------
 /// Writes a formatted string inside another string.
 /// \param pStr  Storage string.
 /// \param pFormat  Format string.