diff --git a/sysmoOCTSIM/command.c b/sysmoOCTSIM/command.c
index 6fa25cf..454cd2f 100644
--- a/sysmoOCTSIM/command.c
+++ b/sysmoOCTSIM/command.c
@@ -81,7 +81,7 @@
 	unsigned int i = 0;
 
 	/* yield CPU after maximum of 10 received characters */
-	while (usart_async_is_rx_not_empty(&UART_debug) && (i < 10)) {
+	while (usart_async_rings_is_rx_not_empty(&UART_debug) && (i < 10)) {
 		int c = getchar();
 		if (c < 0)
 			return;
diff --git a/sysmoOCTSIM/driver_init.c b/sysmoOCTSIM/driver_init.c
index 8a50925..0b6b190 100644
--- a/sysmoOCTSIM/driver_init.c
+++ b/sysmoOCTSIM/driver_init.c
@@ -33,7 +33,7 @@
 #define SIM6_BUFFER_SIZE 16
 
 /*! The buffer size for USART */
-#define UART_DEBUG_BUFFER_SIZE 32
+#define UART_DEBUG_BUFFER_SIZE 256
 
 struct usart_async_descriptor SIM0;
 struct usart_async_descriptor SIM1;
@@ -51,9 +51,10 @@
 static uint8_t SIM5_buffer[SIM5_BUFFER_SIZE];
 static uint8_t SIM6_buffer[SIM6_BUFFER_SIZE];
 
-struct usart_async_descriptor UART_debug;
+struct usart_async_rings_descriptor UART_debug;
 
-static uint8_t UART_DEBUG_buffer[UART_DEBUG_BUFFER_SIZE];
+static uint8_t UART_DEBUG_buffer_rx[UART_DEBUG_BUFFER_SIZE];
+static uint8_t UART_DEBUG_buffer_tx[UART_DEBUG_BUFFER_SIZE];
 
 /**
  * \brief USART Clock initialization function
@@ -349,7 +350,7 @@
 void UART_debug_init(void)
 {
 	UART_debug_CLOCK_init();
-	usart_async_init(&UART_debug, SERCOM7, UART_DEBUG_buffer, UART_DEBUG_BUFFER_SIZE, (void *)NULL);
+	usart_async_rings_init(&UART_debug, SERCOM7, UART_DEBUG_buffer_rx, UART_DEBUG_BUFFER_SIZE, UART_DEBUG_buffer_tx, UART_DEBUG_BUFFER_SIZE, (void *)NULL);
 	UART_debug_PORT_init();
 }
 
diff --git a/sysmoOCTSIM/driver_init.h b/sysmoOCTSIM/driver_init.h
index 9d009b9..6c4f3a1 100644
--- a/sysmoOCTSIM/driver_init.h
+++ b/sysmoOCTSIM/driver_init.h
@@ -21,15 +21,9 @@
 #include <hal_io.h>
 #include <hal_sleep.h>
 
-#include <hal_usart_async.h>
-#include <hal_usart_async.h>
-#include <hal_usart_async.h>
-#include <hal_usart_async.h>
-#include <hal_usart_async.h>
-#include <hal_usart_async.h>
-#include <hal_usart_async.h>
-
 #include <hal_usart_sync.h>
+#include <hal_usart_async.h>
+#include <hal_usart_async_rings.h>
 
 #include "hal_usb_device.h"
 
@@ -40,7 +34,7 @@
 extern struct usart_async_descriptor SIM4;
 extern struct usart_async_descriptor SIM5;
 extern struct usart_async_descriptor SIM6;
-extern struct usart_async_descriptor UART_debug;
+extern struct usart_async_rings_descriptor UART_debug;
 
 void SIM0_PORT_init(void);
 void SIM0_CLOCK_init(void);
diff --git a/sysmoOCTSIM/manual_test.c b/sysmoOCTSIM/manual_test.c
index 526414a..d6852bc 100644
--- a/sysmoOCTSIM/manual_test.c
+++ b/sysmoOCTSIM/manual_test.c
@@ -203,7 +203,7 @@
 	int c;
 
 	do {
-	} while (!usart_async_is_rx_not_empty(&UART_debug));
+	} while (!usart_async_rings_is_rx_not_empty(&UART_debug));
 
 	c = getchar();
 	if (c < 0)
diff --git a/sysmoOCTSIM/stdio_start.c b/sysmoOCTSIM/stdio_start.c
index e2fb0c2..8a15c88 100644
--- a/sysmoOCTSIM/stdio_start.c
+++ b/sysmoOCTSIM/stdio_start.c
@@ -9,13 +9,13 @@
 #include "atmel_start.h"
 #include "stdio_start.h"
 
-static void UART_debug_rx_cb(const struct usart_async_descriptor *const io_descr)
+static void UART_debug_rx_cb(const struct usart_async_rings_descriptor *const io_descr)
 {
 }
 
 void stdio_redirect_init(void)
 {
-	usart_async_register_callback(&UART_debug, USART_ASYNC_RXC_CB, UART_debug_rx_cb); // if no callback function is registered receive won't work, even if the callback does nothing
-	usart_async_enable(&UART_debug);
+	usart_async_rings_register_callback(&UART_debug, USART_ASYNC_RXC_CB, UART_debug_rx_cb); // if no callback function is registered receive won't work, even if the callback does nothing
+	usart_async_rings_enable(&UART_debug);
 	stdio_io_init(&UART_debug.io);
 }