diff --git a/srv/debug.c b/srv/debug.c
index 44711ac..416880c 100644
--- a/srv/debug.c
+++ b/srv/debug.c
@@ -8,53 +8,75 @@
 //--includes--------------------------------------------------------------------
 
 #include "debug.h"
+#include "dma_mbuf.h"
+#include "format.h"
+
+#if DEBUG_TRACE || DEBUG_WARN || DEBUG_ERROR
 
 
 //--local definitions-----------------------------------------------------------
 
-#define BUFFER_SIZE 83  //80 char line + \n + 2 bytes for index
-#define BUFFER_NB    3  //1 buffer in write, one in transfer and one waiting
+static uint32_t write_debug(uint8_t c, void* arg);
+
+#define BUFFER_SIZE 162  //(80 char line + \n) * 2
+
 
 //--local variables-------------------------------------------------------------
 
-static enum UsartPeriph usart_periph;
-static uint8_t tx_buffer1[BUFFER_SIZE];
-static uint8_t tx_buffer2[BUFFER_SIZE];
-static uint8_t tx_buffer3[BUFFER_SIZE];
-static uint8_t* tx_buffers[BUFFER_NB] = {tx_buffer1, tx_buffer2, tx_buffer3};
+static struct DmaMultiBuffer mbuf;
+static uint8_t tx_buffer[BUFFER_SIZE];
 
 
 //--public functions------------------------------------------------------------
 
-#if DEBUG_TRACE || DEBUG_WARN || DEBUG_ERROR
-
 void _debug_init(enum UsartPeriph usart, enum GpioPort tx_port,
 		enum GpioPin tx_pin)
 {
-	usart_periph = usart;
 	gpio_configure(tx_port, tx_pin, GPIO_MODE_OUTPUT_FAST,
 			GPIO_CONFIG_OUT_ALT_PUSH_PULL);
-	usart_configure(usart_periph, USART_CONFIG_8N1, 1152000);
-
-	usart_set_tx_buffer(USART_PERIPH_3, tx_buffers, BUFFER_SIZE, BUFFER_NB,
-			DMA_CONFIG_PRIO_LOW);
+	usart_configure(usart, USART_CONFIG_8N1, 1000000);
+	dma_mbuf_configure(&mbuf,usart_configure_tx_dma(usart),
+			DMA_CONFIG_PRIO_LOW, tx_buffer, BUFFER_SIZE);
 
 	debug_trace("\n");
-	debug_trace("--------------------------------------------------------------------------------\n");
+	debug_trace("------------------------------------------------------------------------------\n");
 	debug_trace("starting debug software\n");
 	debug_trace("compiled on " __DATE__ " at " __TIME__ "\n");
-	debug_trace("--------------------------------------------------------------------------------\n");
+	debug_trace("------------------------------------------------------------------------------\n");
 }
 
-void _debug_trace(char* format, ...)
+void _debug_print(const char* restrict header,
+		const char* restrict format, ...)
 {
-	while(*format != '\0') {
-		while(usart_write_byte(usart_periph, *format)) {}
-		++format;
-	}
+	va_list va;
+	va_start(va, format);
+	format_vfctprintf(write_debug, nullptr, header, va);
+	format_vfctprintf(write_debug, nullptr, format, va);
+	va_end(va);
+	write_debug('\n', nullptr);
+
+	//ensure everything is written when done
+	while (dma_mbuf_switch(&mbuf)) {}
 }
 
-#endif
 
 //--local functions-------------------------------------------------------------
 
+/**
+ * Callback to use with format_vfctprintf() to print caracters to the debug port
+ */
+static uint32_t write_debug(uint8_t c, void* arg)
+{
+	(void)arg; //unused, required because of FormatCallback
+
+	while (dma_mbuf_write_byte(&mbuf, c))
+	{
+		//buffer is full, wait until transfer started
+		while (dma_mbuf_switch(&mbuf)) {}
+	}
+
+	return 0;
+}
+
+#endif //DEBUG_TRACE || DEBUG_WARN || DEBUG_ERROR
+
diff --git a/srv/debug.h b/srv/debug.h
index cd511d6..523b117 100644
--- a/srv/debug.h
+++ b/srv/debug.h
@@ -13,11 +13,10 @@
 #include "../drv/usart.h"
 #include "../drv/gpio.h"
 
-#include "stdint.h"
-
 #define DEBUG_TRACE 1
-#define DEBUG_WARN 0
-#define DEBUG_ERROR 0
+#define DEBUG_WARN 1
+#define DEBUG_ERROR 1
+
 
 //--type definitions------------------------------------------------------------
 
@@ -28,19 +27,40 @@
 #endif
 
 #if DEBUG_TRACE
-#define debug_trace(format, ...) _debug_trace(format __VA_OPT__(,) __VA_ARGS__)
+/**
+ * Prints a trace message on the debug port. This function should return
+ * immediately, provided that the message's length doesn't exceed 80 caracters
+ * and that it isn't called in very quick succession. Otherwise, it will block
+ * until the internal buffering system is ready to accept the message
+ */
+#define debug_trace(format, ...) _debug_print("T:", \
+		format __VA_OPT__(,) __VA_ARGS__)
 #else
 #define debug_trace(format, ...) do {} while (0)
 #endif
 
 #if DEBUG_WARN
-#define debug_warn(format, ...) _debug_warn(format __VA_OPT__(,) __VA_ARGS__)
+/**
+ * Prints a warning message on the debug port. This function should return
+ * immediately, provided that the message's length doesn't exceed 80 caracters
+ * and that it isn't called in very quick succession. Otherwise, it will block
+ * until the internal buffering system is ready to accept the message
+ */
+#define debug_warn(format, ...) _debug_print("W:", \
+		format __VA_OPT__(,) __VA_ARGS__)
 #else
 #define debug_warn(format, ...) do {} while (0)
 #endif
 
 #if DEBUG_ERROR
-#define debug_error(format, ...) _debug_error(format __VA_OPT__(,) __VA_ARGS__)
+/**
+ * Prints an error message on the debug port. This function should return
+ * immediately, provided that the message's length doesn't exceed 80 caracters
+ * and that it isn't called in very quick succession. Otherwise, it will block
+ * until the internal buffering system is ready to accept the message
+ */
+#define debug_error(format, ...) _debug_print("E:", \
+		format __VA_OPT__(,) __VA_ARGS__)
 #else
 #define debug_error(format, ...) do {} while (0)
 #endif
@@ -48,12 +68,30 @@
 
 //--functions-------------------------------------------------------------------
 
+#if DEBUG_TRACE || DEBUG_WARN || DEBUG_ERROR
+
+/**
+ * Initializes the debug system to use the given usart peripheral on the given
+ * tx port, printing a banner if traces are enabled.
+ * The usart doesn't need to be configured, neither does the tx port.
+ *
+ * This function shouldn't be called directly. Instead, use the debug_init macro
+ */
 void _debug_init(enum UsartPeriph usart, enum GpioPort tx_port,
 		enum GpioPin tx_pin);
-void _debug_trace(char* format, ...);
-void _debug_warn(char* format, ...);
-void _debug_error(char* format, ...);
 
+/**
+ * Prints a debug message on the debug port with the given header. This function
+ * should return immediately, provided that the message's length doesn't exceed
+ * 80 caracters and that it isn't called in very quick succession. Otherwise, it
+ * will block until the internal buffering system is ready to accept the message
+ *
+ * This function shouldn't be called directly. Instead, use the debug macros
+ */
+void _debug_print(const char* restrict header,
+		const char* restrict format, ...);
+
+#endif
 
 #endif //_DEBUG_H_
 
diff --git a/srv/format.c b/srv/format.c
new file mode 100644
index 0000000..ccf392e
--- /dev/null
+++ b/srv/format.c
@@ -0,0 +1,265 @@
+/** @file format.c
+ * Module handling various formating functions
+ *
+ * The module provides a lightweight printf function and the attached tools
+ */
+
+//--includes--------------------------------------------------------------------
+
+#include "format.h"
+
+
+//--local definitions-----------------------------------------------------------
+
+struct BufferArg {
+	char* restrict buffer;
+	uint32_t buffer_size;
+	uint32_t byte_index;
+};
+
+static uint32_t buffer_write(uint8_t byte, void* arg);
+static uint32_t render_format(FormatCallback callback, void* arg,
+		const char* restrict format, va_list va);
+static uint32_t render_signed(FormatCallback callback, void* arg,
+		int32_t number, uint8_t base, uint8_t width);
+static uint32_t render_unsigned(FormatCallback callback, void* arg,
+		uint32_t number, uint8_t base, uint8_t width, bool zero_padding);
+
+
+//--local variables-------------------------------------------------------------
+
+//--public functions------------------------------------------------------------
+
+uint32_t format_snprintf(char* restrict buffer, uint32_t buffer_size,
+		const char* restrict format, ...)
+{
+	va_list va;
+	va_start(va, format);
+	struct BufferArg arg = { buffer, buffer_size, 0 };
+	uint32_t ret = render_format(buffer_write, &arg, format, va);
+	va_end(va);
+	return ret;
+}
+
+uint32_t format_fctprintf(FormatCallback callback, void* arg,
+		const char* restrict format, ...)
+{
+	va_list va;
+	va_start(va, format);
+	uint32_t ret = render_format(callback, arg, format, va);
+	va_end(va);
+	return ret;
+}
+
+uint32_t format_vfctprintf(FormatCallback callback, void* arg,
+		const char* restrict format, va_list va)
+{
+	return render_format(callback, arg, format, va);
+}
+
+
+//--local functions-------------------------------------------------------------
+
+/**
+ * FormatCallback to write into a regular buffer. A pointer to BufferArg shall
+ * be passed as arg.
+ *
+ * Returns 0 if everything went as expected, 1 otherwise
+ */
+static uint32_t buffer_write(uint8_t byte, void* arg)
+{
+	struct BufferArg* buffer_arg = (struct BufferArg*)arg;
+	if (buffer_arg->byte_index >= buffer_arg->buffer_size) {
+		return 1;
+	}
+
+	buffer_arg->buffer[buffer_arg->byte_index] = byte;
+	++buffer_arg->byte_index;
+	return 0;
+}
+
+/**
+ * Renders the given format to the output defined by the provided callback,
+ * formatting accordingly the provided arguments
+ *
+ * Returns 0 if everything went as expected, 1 otherwise
+ */
+static uint32_t render_format(FormatCallback callback, void* arg,
+		const char* restrict format, va_list va)
+{
+	uint8_t width = 0;
+	bool in_format = false;
+	bool zero_padding = false;
+
+	for (const char* c = format; *c != '\0'; ++c) {
+
+		if (in_format) {
+			switch (*c) {
+				case '%':
+					if (callback('%', arg)) return 1;
+					break;
+				case 'c':
+					if (callback((uint8_t)va_arg(va, uint32_t), arg)) {
+						return 1;
+					}
+					break;
+				case 's':
+					{
+						const char* str = va_arg(va, const char*);
+						for (const char* c2 = str; *c2 != '\0'; ++c2) {
+							if (callback(*c2, arg)) return 1;
+						}
+					}
+					break;
+				case 'i':
+					if (render_signed(callback, arg, va_arg(va, int32_t),
+								10, width)) {
+						return 1;
+					}
+					break;
+				case 'u':
+					if (render_unsigned(callback, arg, va_arg(va, uint32_t),
+								10, width, zero_padding)) {
+						return 1;
+					}
+					break;
+				case 'x':
+					if (render_unsigned(callback, arg, va_arg(va, uint32_t),
+								16, width, zero_padding)) {
+						return 1;
+					}
+					break;
+				case '0':
+					if (width == 0) {
+						zero_padding = true;
+						continue;
+					}
+					// fall through
+				case '1':
+				case '2':
+				case '3':
+				case '4':
+				case '5':
+				case '6':
+				case '7':
+				case '8':
+				case '9':
+					width *= 10;
+					width += (*c - '0');
+					continue;
+				default:
+					//TODO manage error
+					break;
+			}
+		} else {
+			switch (*c) {
+				case '%':
+					in_format = true;
+					zero_padding = false;
+					width = 0;
+					continue;
+				default:
+					if (callback(*c, arg)) return 1;
+					break;
+			}
+		}
+
+		in_format = false;
+	}
+
+	return 0;
+}
+
+/**
+ * Formats a signed integer and renders it to the output defined by the provided
+ * callback
+ *
+ * Returns 0 if everything went as expected, 1 otherwise
+ */
+static uint32_t render_signed(FormatCallback callback, void* arg,
+		int32_t number, uint8_t base, uint8_t width)
+{
+	if (width > 0 && number < 0) {
+		--width;
+	}
+
+	if (width > 0) {
+		uint32_t abs_number;
+		if (number < 0) {
+			abs_number = -number;
+		} else {
+			abs_number = number;
+		}
+
+		uint32_t base_power = base;
+		while (width > 0 && base_power <= abs_number) {
+			base_power *= base;
+			--width;
+		}
+		if (width > 0) {
+			--width;
+		}
+
+		while (width > 0) {
+			--width;
+			if (callback(' ', arg)) return 1;
+		}
+	}
+
+	if (number < 0) {
+		callback('-', arg);
+		number = -number;
+	}
+
+	return render_unsigned(callback, arg, (uint32_t)number, base, 0, false);
+}
+
+/**
+ * Formats an unsigned integer and renders it to the output defined by the
+ * provided callback
+ *
+ * Returns 0 if everything went as expected, 1 otherwise
+ */
+static uint32_t render_unsigned(FormatCallback callback, void* arg,
+		 uint32_t number, uint8_t base, uint8_t width, bool zero_padding)
+{
+	uint32_t base_power = base;
+
+	while (base_power <= number) {
+		base_power *= base;
+		if (width > 0) {
+			--width;
+		}
+	}
+	if (width > 0) {
+		--width;
+	}
+
+	while (width > 0) {
+		--width;
+		if (zero_padding) {
+			if (callback('0', arg)) return 1;
+		} else {
+			if (callback(' ', arg)) return 1;
+		}
+	}
+
+	while (base_power > 1) {
+		base_power /= base;
+
+		uint8_t digit = 0;
+		while (number >= base_power) {
+			number -= base_power;
+			++digit;
+		}
+
+		if (digit < 10) {
+			if (callback('0' + digit, arg)) return 1;
+		} else {
+			if (callback('A' + digit - 10, arg)) return 1;
+		}
+	}
+
+	return 0;
+}
+
diff --git a/srv/format.h b/srv/format.h
new file mode 100644
index 0000000..a735542
--- /dev/null
+++ b/srv/format.h
@@ -0,0 +1,57 @@
+/** @file format.h
+ * Module handling various formating functions
+ *
+ * The module provides a lightweight printf function and the attached tools
+ */
+
+#ifndef _FORMAT_H_
+#define _FORMAT_H_
+
+//--includes--------------------------------------------------------------------
+
+#include <stdint.h>
+#include <stdarg.h>
+
+
+//--type definitions------------------------------------------------------------
+
+typedef uint32_t (*FormatCallback)(uint8_t byte, void* arg);
+
+
+//--functions-------------------------------------------------------------------
+
+/**
+ * Custom implementation of snprintf. Print the given format into the given
+ * buffer with the attached arguments properly formated.
+ *
+ * This function only provided a minimal subset of the standard library's
+ * snprintf : %c, %s, %i, %d, %x as well as right-justified padding for %d and
+ * %x
+ *
+ * Returns 0 if everything went as expected, 1 otherwise
+ */
+uint32_t format_snprintf(char* restrict buffer, uint32_t buffer_size,
+		const char* restrict format, ...);
+
+/**
+ * Custom implementation of fprintf using a callback instead of a file pointer.
+ * Print the given format using the given callback with the attached arguments
+ * properly formated.
+ *
+ * This function only provided a minimal subset of the standard library's
+ * snprintf : %c, %s, %i, %d, %x as well as right-justified padding for %d and
+ * %x
+ *
+ * Returns 0 if everything went as expected, 1 otherwise
+ */
+uint32_t format_fctprintf(FormatCallback callback, void* arg,
+		const char* restrict format, ...);
+
+/**
+ * Variadic variation of format_fctprintf(), see the later for more information
+ */
+uint32_t format_vfctprintf(FormatCallback callback, void* arg,
+		const char* restrict format, va_list va);
+
+#endif //_FORMAT_H_
+