zephyr BLE创建自定义服务

news2024/11/14 20:41:12

LBS服务介绍

在这里插入图片描述

实现过程

定义 GATT 服务及其特性的 128 位 UUID。包括服务UUID，特征的UUID。

#define BT_UUID_LBS_VAL BT_UUID_128_ENCODE(0X00001523,0X1212,0XEFDE,0x1523,0x785feabcd123)

/** @brief Button Characteristic UUID. */
#define BT_UUID_LBS_BUTTON_VAL \
	BT_UUID_128_ENCODE(0x00001524, 0x1212, 0xefde, 0x1523, 0x785feabcd123)

/** @brief LED Characteristic UUID. */
#define BT_UUID_LBS_LED_VAL \
	BT_UUID_128_ENCODE(0x00001525, 0x1212, 0xefde, 0x1523, 0x785feabcd123)

创建服务并将其添加到蓝牙 LE 堆栈。
通过宏BT_GATT_SERVICE_DEFINE()静态创建和添加服务

BT_GATT_SERVICE_DEFINE(my_lbs_svc,
BT_GATT_PRIMARY_SERVICE(BT_UUID_LBS),
);

创建并添加自定义按钮特征。

	BT_GATT_CHARACTERISTIC(BT_UUID_LBS_BUTTON,
			       BT_GATT_CHRC_READ,
			       BT_GATT_PERM_READ, read_button, NULL,
			       &button_state),

创建自定义LED特征

	BT_GATT_CHARACTERISTIC(BT_UUID_LBS_LED,
			       BT_GATT_CHRC_WRITE,
			       BT_GATT_PERM_WRITE,
			       NULL, write_led, NULL),

实现上面的read_button和write_led函数。
回调函数的函数签名是有固定格式的。bt_gatt_attr_read_func_t 在这里插入图片描述协议栈收到读取请求，会调用我们自己写的回调函数，回调函数会调用bt_gatt_attr_read ()返回数据给协议栈，然后协议栈发送数据出去。

static ssize_t read_button(struct bt_conn *conn,
			  const struct bt_gatt_attr *attr,
			  void *buf,
			  uint16_t len,
			  uint16_t offset)
{
	//get a pointer to button_state which is passed in the BT_GATT_CHARACTERISTIC() and stored in attr->user_data
	const char *value = attr->user_data;

	LOG_DBG("Attribute read, handle: %u, conn: %p", attr->handle,
		(void *)conn);

	if (lbs_cb.button_cb) {
		// Call the application callback function to update the get the current value of the button
		button_state = lbs_cb.button_cb();
		return bt_gatt_attr_read(conn, attr, buf, len, offset, value,
					 sizeof(*value));
	}

	return 0;
}

写LED的回调函数

static ssize_t write_led(struct bt_conn *conn,
			 const struct bt_gatt_attr *attr,
			 const void *buf,
			 uint16_t len, uint16_t offset, uint8_t flags)
{
	LOG_DBG("Attribute write, handle: %u, conn: %p", attr->handle,
		(void *)conn);

	if (len != 1U) {
		LOG_DBG("Write led: Incorrect data length");
		return BT_GATT_ERR(BT_ATT_ERR_INVALID_ATTRIBUTE_LEN);
	}

	if (offset != 0) {
		LOG_DBG("Write led: Incorrect data offset");
		return BT_GATT_ERR(BT_ATT_ERR_INVALID_OFFSET);
	}

	if (lbs_cb.led_cb) {
		//Read the received value 
		uint8_t val = *((uint8_t *)buf);

		if (val == 0x00 || val == 0x01) {
			//Call the application callback function to update the LED state
			lbs_cb.led_cb(val ? true : false);
		} else {
			LOG_DBG("Write led: Incorrect value");
			return BT_GATT_ERR(BT_ATT_ERR_VALUE_NOT_ALLOWED);
		}
	}

	return len;
}