diff --git a/lib/radio_gps.c b/lib/radio_gps.c
new file mode 100644
index 0000000..a0f1fbc
--- /dev/null
+++ b/lib/radio_gps.c
@@ -0,0 +1,127 @@
+/* This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+/** library for receiving NMEA-0183 GPS messages (code)
+ *  @file radio_gps.c
+ *  @author King Kévin <kingkevin@cuvoodoo.info>
+ *  @date 2017
+ *  @note peripherals used: USART @ref radio_gps_usart
+ */
+
+/* standard libraries */
+#include <stdint.h> // standard integer types
+#include <stdio.h> // standard I/O facilities
+#include <stdlib.h> // general utilities
+
+/* STM32 (including CM3) libraries */
+#include <libopencm3/stm32/rcc.h> // real-time control clock library
+#include <libopencm3/stm32/gpio.h> // general purpose input output library
+#include <libopencm3/stm32/usart.h> // universal synchronous asynchronous receiver transmitter library
+#include <libopencm3/cm3/nvic.h> // interrupt handler
+#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
+
+#include "radio_gps.h" // GPS header and definitions
+#include "global.h" // common methods
+
+/** @defgroup radio_gps_usart USART peripheral used for communication with the GPS
+ *  @{
+ */
+#define RADIO_GPS_USART 3 /**< USART peripheral */
+/** @} */
+
+#define RADIO_GPS_BAUDRATE 9600 /**< USART baudrate for the GPS communication, in bits per second (with 8N1 8 bits, no parity bit, 1 stop bit settings) */
+
+static volatile char radio_gps_buffer[82] = {0}; /**< buffer for received data (82 chars is the maximum NMEA-0183 message length) */
+static volatile uint8_t radio_gps_buffer_i = 0; /**< current position of read received data */
+
+volatile bool radio_gps_received = false;
+volatile char radio_gps_message[82+1] = {0};
+
+void radio_gps_setup(void)
+{
+	/* enable USART I/O peripheral */
+	rcc_periph_clock_enable(USART_PORT_RCC(RADIO_GPS_USART)); // enable clock for USART port peripheral
+	rcc_periph_clock_enable(USART_RCC(RADIO_GPS_USART)); // enable clock for USART peripheral
+	rcc_periph_clock_enable(RCC_AFIO); // enable pin alternate function (USART)
+	gpio_set_mode(USART_PORT(RADIO_GPS_USART), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, USART_PIN_RX(RADIO_GPS_USART)); // setup GPIO pin USART receive
+	gpio_set(USART_PORT(RADIO_GPS_USART), USART_PIN_RX(RADIO_GPS_USART)); // pull up to avoid noise when not connected
+
+	/* setup USART parameters */
+	usart_set_baudrate(USART(RADIO_GPS_USART), RADIO_GPS_BAUDRATE);
+	usart_set_databits(USART(RADIO_GPS_USART), 8);
+	usart_set_stopbits(USART(RADIO_GPS_USART), USART_STOPBITS_1);
+	usart_set_mode(USART(RADIO_GPS_USART), USART_MODE_RX); // we only need to receive messages
+	usart_set_parity(USART(RADIO_GPS_USART), USART_PARITY_NONE);
+	usart_set_flow_control(USART(RADIO_GPS_USART), USART_FLOWCONTROL_NONE);
+
+	nvic_enable_irq(USART_IRQ(RADIO_GPS_USART)); // enable the USART interrupt
+	usart_enable_rx_interrupt(USART(RADIO_GPS_USART)); // enable receive interrupt
+	usart_enable(USART(RADIO_GPS_USART)); // enable USART
+
+	/* reset buffer states */
+	radio_gps_received = false;
+	radio_gps_buffer_i = 0;
+}
+
+/** USART interrupt service routine called when data has been received */
+void USART_ISR(RADIO_GPS_USART)(void)
+{
+	if (usart_get_flag(USART(RADIO_GPS_USART), USART_SR_RXNE)) { // data has been received
+		char c =  usart_recv(USART(RADIO_GPS_USART)); // put character in buffer (and clear flag)
+		// only save data if there is space in the buffer
+		if (radio_gps_buffer_i<LENGTH(radio_gps_buffer)) {
+			radio_gps_buffer[radio_gps_buffer_i++] = c;
+		}
+		if ('\n'==c) { // end of message received
+			// verify if the message is correctly formatted
+			if (radio_gps_buffer_i<1 || '$'!=radio_gps_buffer[0]) {
+				goto malformatted;
+			} else if (radio_gps_buffer_i<2 || '\r'!=radio_gps_buffer[radio_gps_buffer_i-2]) {
+				goto malformatted;
+			} else { // verify checksum when available
+				uint8_t checksum_calc = 0;
+				uint8_t checksum_i = 0;
+				bool checkum_present = false;
+				for (checksum_i = 1; checksum_i < radio_gps_buffer_i-2; checksum_i++) {
+					if ('*'==radio_gps_buffer[checksum_i]) {
+						checkum_present = true;
+						break;
+					} else {
+						checksum_calc ^= radio_gps_buffer[checksum_i];
+					}
+				}
+				if (checkum_present) {
+					if (checksum_i!=radio_gps_buffer_i-5) { // only 2 checksum character should be remaining
+						goto malformatted;
+					} else if (checksum_calc-(radio_gps_buffer[checksum_i+1]-'0')*0x10-(radio_gps_buffer[checksum_i+2]-'0')) { // checksum does not match
+						goto malformatted;
+					}
+				}
+			}
+			// copy message to user
+			for (uint8_t i = 0; i < radio_gps_buffer_i && i < LENGTH(radio_gps_message); i++) {
+				radio_gps_message[i] = radio_gps_buffer[i];
+			}
+			// terminate string
+			if (radio_gps_buffer_i<LENGTH(radio_gps_message)) {
+				radio_gps_message[radio_gps_buffer_i] = '\0';
+			} else {
+				radio_gps_message[LENGTH(radio_gps_message)-1]  = '\0';
+			}
+			radio_gps_received = true; // notify user a message is available
+malformatted:
+			radio_gps_buffer_i = 0; // reset buffer
+		}
+	}
+}
diff --git a/lib/radio_gps.h b/lib/radio_gps.h
new file mode 100644
index 0000000..dd170e7
--- /dev/null
+++ b/lib/radio_gps.h
@@ -0,0 +1,29 @@
+/* This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+/** library for receiving NMEA-0183 GPS messages (API)
+ *  @file radio_gps.h
+ *  @author King Kévin <kingkevin@cuvoodoo.info>
+ *  @date 2017
+ *  @note peripherals used: USART @ref radio_gps_usart
+ */
+#pragma once
+
+/** has a NMEA-0183 GPS message been received */
+extern volatile bool radio_gps_received;
+/** last valid NMEA-0183 GPS message received (including \r\n ending and \0) */
+extern volatile char radio_gps_message[82+1];
+
+/** setup USART peripheral for GPS communication */
+void radio_gps_setup(void);