examples: Adding a new example that demonstrates BLE Nordic UART Service (NUS)

CMakeLists.txt

@@ -114,6 +114,7 @@ add_subdirectory(examples/ble_scan)
 add_subdirectory(examples/discover)
 add_subdirectory(examples/read_write)
 add_subdirectory(examples/gatttool)
+add_subdirectory(examples/nordic_uart)
 
 #
 # Packaging

examples/nordic_uart/CMakeLists.txt

@@ -0,0 +1,30 @@
+#
+#
+#  GattLib - GATT Library
+#
+#  Copyright (C) 2017  Olivier Martin <olivier@labapart.org>
+#
+#
+#  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 2 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, write to the Free Software
+#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#
+
+cmake_minimum_required(VERSION 2.6)
+
+set(nordic_uart_LIBS gattlib)
+
+set(nordic_uart_SRCS nordic_uart.c)
+
+add_executable(nordic_uart ${nordic_uart_SRCS})
+target_link_libraries(nordic_uart ${nordic_uart_LIBS})

examples/nordic_uart/nordic_uart.c

@@ -0,0 +1,134 @@
+/*
+ *
+ *  GattLib - GATT Library
+ *
+ *  Copyright (C) 2016-2017  Olivier Martin <olivier@labapart.org>
+ *
+ *
+ *  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 2 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, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+
+#include "gattlib.h"
+
+#define NUS_CHARACTERISTIC_TX_UUID	"6e400002-b5a3-f393-e0a9-e50e24dcca9e"
+#define NUS_CHARACTERISTIC_RX_UUID	"6e400003-b5a3-f393-e0a9-e50e24dcca9e"
+
+gatt_connection_t* m_connection;
+
+void notification_cb(uint16_t handle, const uint8_t* data, size_t data_length, void* user_data) {
+	for(int i = 0; i < data_length; i++) {
+		printf("%c", data[i]);
+	}
+}
+
+static void usage(char *argv[]) {
+	printf("%s <device_address>\n", argv[0]);
+}
+
+void int_handler(int dummy) {
+	gattlib_disconnect(m_connection);
+	exit(0);
+}
+
+int main(int argc, char *argv[]) {
+	char input[256];
+	char* input_ptr;
+	int i, ret, total_length, length = 0;
+	uuid_t nus_characteristic_tx_uuid;
+	uuid_t nus_characteristic_rx_uuid;
+
+	if (argc != 2) {
+		usage(argv);
+		return 1;
+	}
+
+	m_connection = gattlib_connect(NULL, argv[1], BDADDR_LE_RANDOM, BT_SEC_LOW, 0, 0);
+	if (m_connection == NULL) {
+		fprintf(stderr, "Fail to connect to the bluetooth device.\n");
+		return 1;
+	}
+
+	// Convert characteristics to their respective UUIDs
+	ret = gattlib_string_to_uuid(NUS_CHARACTERISTIC_TX_UUID, strlen(NUS_CHARACTERISTIC_TX_UUID) + 1, &nus_characteristic_tx_uuid);
+	if (ret) {
+		fprintf(stderr, "Fail to convert characteristic TX to UUID.\n");
+		return 1;
+	}
+	ret = gattlib_string_to_uuid(NUS_CHARACTERISTIC_RX_UUID, strlen(NUS_CHARACTERISTIC_RX_UUID) + 1, &nus_characteristic_rx_uuid);
+	if (ret) {
+		fprintf(stderr, "Fail to convert characteristic RX to UUID.\n");
+		return 1;
+	}
+
+	// Look for handle for NUS_CHARACTERISTIC_TX_UUID
+	gattlib_characteristic_t* characteristics;
+	int characteristic_count;
+	ret = gattlib_discover_char(m_connection, &characteristics, &characteristic_count);
+	if (ret) {
+		fprintf(stderr, "Fail to discover characteristic.\n");
+		return 1;
+	}
+
+	uint16_t tx_handle = 0, rx_handle = 0;
+	for (i = 0; i < characteristic_count; i++) {
+		if (gattlib_uuid_cmp(&characteristics[i].uuid, &nus_characteristic_tx_uuid) == 0) {
+			tx_handle = characteristics[i].value_handle;
+		} else if (gattlib_uuid_cmp(&characteristics[i].uuid, &nus_characteristic_rx_uuid) == 0) {
+			rx_handle = characteristics[i].value_handle;
+		}
+	}
+	if (tx_handle == 0) {
+		fprintf(stderr, "Fail to find NUS TX characteristic.\n");
+		return 1;
+	} else if (rx_handle == 0) {
+		fprintf(stderr, "Fail to find NUS RX characteristic.\n");
+		return 1;
+	}
+	free(characteristics);
+
+	// Enable Status Notification
+	uint16_t enable_notification = 0x0001;
+	gattlib_write_char_by_handle(m_connection, rx_handle + 1, &enable_notification, sizeof(enable_notification));
+
+	// Register notification handler
+	gattlib_register_notification(m_connection, notification_cb, NULL);
+
+	// Register handler to catch Ctrl+C
+	signal(SIGINT, int_handler);
+
+	while(1) {
+		fgets(input, sizeof(input), stdin);
+
+		// NUS TX can only receive 20 bytes at a time
+		input_ptr = input;
+		for (total_length = strlen(input) + 1; total_length > 0; total_length -= length) {
+			length     = MIN(total_length, 20);
+			ret = gattlib_write_char_by_handle(m_connection, tx_handle, input_ptr, length);
+			if (ret) {
+				fprintf(stderr, "Fail to send data to NUS TX characteristic.\n");
+				return 1;
+			}
+			input_ptr += length;
+		}
+	}
+
+	return 0;
+}