测向|主设备_nrf52832学习笔记蓝牙从机广播

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蓝牙从机要想被主机连接&＃xff0c;首先需要发送广播信息&＃xff0c;周围主机通过扫描广播信号&＃xff0c;根据从机的广播信息&＃xff0c;判断是否连接。

蓝牙协议栈初始化

不管是主机还是从机&＃xff0c;要想使用蓝牙功能&＃xff0c;都需要对蓝牙协议栈进行初始化操作

/**&＃64;brief Function for initializing the BLE stack.
*
* &＃64;details Initializes the SoftDevice and the BLE event interrupt.
*/
static void ble_stack_init(void)

ret_code_t err_code;
// 1.协议栈低速时钟初始化并注册状态观察者函数
err_code &＃61; nrf_sdh_enable_request();
APP_ERROR_CHECK(err_code);
// 2.使用默认配置配置蓝牙协议栈
uint32_t ram_start &＃61; 0;
err_code &＃61; nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
APP_ERROR_CHECK(err_code);
// 3.使能协议栈
err_code &＃61; nrf_sdh_ble_enable(&ram_start);
APP_ERROR_CHECK(err_code);
// 4.注册蓝牙事件观察者回调函数
NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);



蓝牙协议栈初始化做了四件事&＃xff1a;

• 协议栈时钟低速初始化并注册状态观察者函数

  
  

  
  

  协议栈运行除了主时钟外还需要一个低速时钟&＃xff0c;低速时钟有三种来源&＃xff0c;根据功耗和硬件选择合适的时钟源。

  
  

  // <0&＃61;> NRF_CLOCK_LF_SRC_RC //内部RC时钟&＃xff0c;比外部低速晶振耗电多10ua左右
// <1&＃61;> NRF_CLOCK_LF_SRC_XTAL //外部低速晶振&＃xff0c;最省电但是需要外接低速晶振
// <2&＃61;> NRF_CLOCK_LF_SRC_SYNTH //内部主时钟产生的低速时钟&＃xff0c;最耗电
#ifndef NRF_SDH_CLOCK_LF_SRC
#define NRF_SDH_CLOCK_LF_SRC 1
#endif
nrf_clock_lf_cfg_t const clock_lf_cfg &＃61;

.source &＃61; NRF_SDH_CLOCK_LF_SRC,
.rc_ctiv &＃61; NRF_SDH_CLOCK_LF_RC_CTIV,
.rc_temp_ctiv &＃61; NRF_SDH_CLOCK_LF_RC_TEMP_CTIV,
.accuracy &＃61; NRF_SDH_CLOCK_LF_ACCURACY //时钟准确度
;

  

  
  

  注册的状态观察者函数其实就是一个中断服务函数的子函数&＃xff0c;用户根据返回的状态信息做出相应处理。比如蓝牙协议栈使能失败&＃xff0c;协议栈会触发一个软中断&＃xff0c;软中断中调用注册的状态观察者函数&＃xff0c;用户在状态观察者函数中根据状态信息点灯或者干别的事情&＃xff0c;方便用户观察协议栈的运行状态。

  
  

• 使用默认配置配置蓝牙协议栈

  
  

  
  

  默认配置信息可以在sdk_config.h中根据自己需要自行修改。
  

  
  

  // 空中包长度 &＃61; NRF_SDH_BLE_GATT_MAX_MTU_SIZE &＃43; 4&＃xff0c;提高蓝牙传输速率时&＃xff0c;可以修改这里
#ifndef NRF_SDH_BLE_GAP_DATA_LENGTH
#define NRF_SDH_BLE_GAP_DATA_LENGTH 27
#endif
// 从机角色个数&＃xff0c;可以连接 ? 个主机
#ifndef NRF_SDH_BLE_PERIPHERAL_LINK_COUNT
#define NRF_SDH_BLE_PERIPHERAL_LINK_COUNT 1
#endif
// 主机角色个数&＃xff0c;可以连接 ? 个从机
#ifndef NRF_SDH_BLE_CENTRAL_LINK_COUNT
#define NRF_SDH_BLE_CENTRAL_LINK_COUNT 0
#endif
// 主机&＃43;从机 总的角色个数
#ifndef NRF_SDH_BLE_TOTAL_LINK_COUNT
#define NRF_SDH_BLE_TOTAL_LINK_COUNT 1
#endif
// 一个连接间隔内可以用于数据传输的事件长度&＃xff0c;以1.25 ms为单位。
// 提高蓝牙传输速率时&＃xff0c;可以修改这里和连接事件长度扩展相配合
#ifndef NRF_SDH_BLE_GAP_EVENT_LENGTH
#define NRF_SDH_BLE_GAP_EVENT_LENGTH 6
#endif
// MTU最大长度 蓝牙4.0 最大23 蓝牙4.2以上最大247
#ifndef NRF_SDH_BLE_GATT_MAX_MTU_SIZE
#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 23
#endif
// NRF_SDH_BLE_GATTS_ATTR_TAB_SIZE - Attribute Table size in bytes. The size must be a multiple of 4.
#ifndef NRF_SDH_BLE_GATTS_ATTR_TAB_SIZE
#define NRF_SDH_BLE_GATTS_ATTR_TAB_SIZE 1408
#endif
// NRF_SDH_BLE_VS_UUID_COUNT - The number of vendor-specific UUIDs.
// 主要每增加一个UUIDs 协议栈消耗RAM会增加0x10
#ifndef NRF_SDH_BLE_VS_UUID_COUNT
#define NRF_SDH_BLE_VS_UUID_COUNT 10
#endif
// NRF_SDH_BLE_SERVICE_CHANGED - Include the Service Changed characteristic in the Attribute Table.
#ifndef NRF_SDH_BLE_SERVICE_CHANGED
#define NRF_SDH_BLE_SERVICE_CHANGED 0
#endif


• 使能协议栈

• 注册蓝牙事件观察者回调函数

GAP初始化

Generic Access Profile(通用访问协议)也就是常说的GAP&＃xff0c;所有蓝牙设备中必须存在的profile。NRF52832 SDK中对GAP的操作均在 ble_gap.h中。

GAP 安全模式

蓝牙配对时输入密码功能是GAP的一部分&＃xff0c;当然也可以选择开放模式&＃xff08;不用输入密码&＃xff09;则不用进行这里的静态密匙设置操作

/**&＃64;brief GAP connection security modes.
*
* Security Mode 0 Level 0: No access permissions at all (this level is not defined by the Bluetooth Core specification).\\n
* Security Mode 1 Level 1: No security is needed (aka open link).\\n
* Security Mode 1 Level 2: Encrypted link required, MITM protection not necessary.\\n
* Security Mode 1 Level 3: MITM protected encrypted link required.\\n
* Security Mode 1 Level 4: LESC MITM protected encrypted link using a 128-bit strength encryption key required.\\n
* Security Mode 2 Level 1: Signing or encryption required, MITM protection not necessary.\\n
* Security Mode 2 Level 2: MITM protected signing required, unless link is MITM protected encrypted.\\n
*/
typedef struct

uint8_t sm : 4; /**
uint8_t lv : 4; /**
ble_gap_conn_sec_mode_t;
//设置静态钥匙
#define STATIC_PASSKEY "123456"
static ble_opt_t m_static_pin_option;
uint8_t passkey[] &＃61; STATIC_PASSKEY;
m_static_pin_option.gap_opt.passkey.p_passkey &＃61; passkey;
err_code &＃61; sd_ble_opt_set(BLE_GAP_OPT_PASSKEY, &m_static_pin_option);


GAP MAC地址设置

蓝牙的MAC地址分为两类

• Public
  

  
  

  需要申请购买, 24bit&＃xff08;MSB&＃xff09;公司ID &＃43; 24bit设备地址

  
  

• Random
  

  
  

  随机地址分为两种

  
  

  
  
  • 静态随机地址
    

    
    

    随机生成的&＃xff0c;其中MSB最高两位必须为 11

    
    

  • 私有随机地址
    
    • Non-Resolvable
      

      
      

      不解析私有地址&＃xff0c;MSB最高两位必须为 00&＃xff0c;隔一段时间会自动变化一次

      
      

    • Resolvable
      

      
      

      解析私有地址&＃xff0c; MSB最高两位必须为 01&＃xff0c; 由24bit&＃xff08;MSB&＃xff09;随机数 &＃43; 24bit hash组成

      
      

一般静态随机地址比较常用&＃xff0c;可以通过 sd_ble_gap_addr_set 函数在广播开始前设置蓝牙MAC地址。

ble_gap_addr_t gap_addr &＃61;

.addr_type &＃61; BLE_GAP_ADDR_TYPE_PUBLIC,
.addr &＃61; 0x00, 0x11, 0x00, 0xE9, 0x81, 0xC9
;
sd_ble_gap_addr_set(&gap_addr);


GAP 蓝牙设备名称

GAP中包含了蓝牙的名称&＃xff0c;但是蓝牙名称信息是通过广播包传递给周围设备的&＃xff0c;因此想要其他设备可以获取自己的蓝牙名称&＃xff0c;需要在广播初始化时向广播包中添加蓝牙名称信息。

#define DEVICE_NAME "Nordic_Blinky"
ble_gap_conn_sec_mode_t sec_mode;
BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);
sd_ble_gap_device_name_set(&sec_mode,(const uint8_t *)DEVICE_NAME, strlen(DEVICE_NAME));


注意大多数手机使用的是UTF-8编码格式&＃xff0c;因此想要手机上显示中文蓝牙设备名&＃xff0c;需要修改MDK文件编码格式为UTF-8

GAP 蓝牙图标

GAP中包含了蓝牙的图标信息&＃xff0c;但是蓝牙图标信息也是通过广播包传递给周围设备的&＃xff0c;因此想要其他设备可以获取对应的蓝牙图标&＃xff0c;需要在广播初始化时向广播包中添加蓝牙图标信息。

/** &＃64;defgroup BLE_APPEARANCES Bluetooth Appearance values
* &＃64;note Retrieved from http://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u&＃61;org.bluetooth.characteristic.gap.appearance.xml
* &＃64; */
#define BLE_APPEARANCE_UNKNOWN 0 /**
#define BLE_APPEARANCE_GENERIC_PHONE 64 /**
#define BLE_APPEARANCE_GENERIC_COMPUTER 128 /**
#define BLE_APPEARANCE_GENERIC_WATCH 192 /**
#define BLE_APPEARANCE_WATCH_SPORTS_WATCH 193 /**
#define BLE_APPEARANCE_GENERIC_CLOCK 256 /**
#define BLE_APPEARANCE_GENERIC_DISPLAY 320 /**
#define BLE_APPEARANCE_GENERIC_REMOTE_CONTROL 384 /**
#define BLE_APPEARANCE_GENERIC_EYE_GLASSES 448 /**
#define BLE_APPEARANCE_GENERIC_TAG 512 /**
#define BLE_APPEARANCE_GENERIC_KEYRING 576 /**
#define BLE_APPEARANCE_GENERIC_MEDIA_PLAYER 640 /**
#define BLE_APPEARANCE_GENERIC_BARCODE_SCANNER 704 /**
#define BLE_APPEARANCE_GENERIC_THERMOMETER 768 /**
#define BLE_APPEARANCE_THERMOMETER_EAR 769 /**
#define BLE_APPEARANCE_GENERIC_HEART_RATE_SENSOR 832 /**
#define BLE_APPEARANCE_HEART_RATE_SENSOR_HEART_RATE_BELT 833 /**
#define BLE_APPEARANCE_GENERIC_BLOOD_PRESSURE 896 /**
#define BLE_APPEARANCE_BLOOD_PRESSURE_ARM 897 /**
#define BLE_APPEARANCE_BLOOD_PRESSURE_WRIST 898 /**
#define BLE_APPEARANCE_GENERIC_HID 960 /**
#define BLE_APPEARANCE_HID_KEYBOARD 961 /**
#define BLE_APPEARANCE_HID_MOUSE 962 /**
#define BLE_APPEARANCE_HID_JOYSTICK 963 /**
#define BLE_APPEARANCE_HID_GAMEPAD 964 /**
#define BLE_APPEARANCE_HID_DIGITIZERSUBTYPE 965 /**
#define BLE_APPEARANCE_HID_CARD_READER 966 /**
#define BLE_APPEARANCE_HID_DIGITAL_PEN 967 /**
#define BLE_APPEARANCE_HID_BARCODE 968 /**
#define BLE_APPEARANCE_GENERIC_GLUCOSE_METER 1024 /**
#define BLE_APPEARANCE_GENERIC_RUNNING_WALKING_SENSOR 1088 /**
#define BLE_APPEARANCE_RUNNING_WALKING_SENSOR_IN_SHOE 1089 /**
#define BLE_APPEARANCE_RUNNING_WALKING_SENSOR_ON_SHOE 1090 /**
#define BLE_APPEARANCE_RUNNING_WALKING_SENSOR_ON_HIP 1091 /**
#define BLE_APPEARANCE_GENERIC_CYCLING 1152 /**
#define BLE_APPEARANCE_CYCLING_CYCLING_COMPUTER 1153 /**
#define BLE_APPEARANCE_CYCLING_SPEED_SENSOR 1154 /**
#define BLE_APPEARANCE_CYCLING_CADENCE_SENSOR 1155 /**
#define BLE_APPEARANCE_CYCLING_POWER_SENSOR 1156 /**
#define BLE_APPEARANCE_CYCLING_SPEED_CADENCE_SENSOR 1157 /**
#define BLE_APPEARANCE_GENERIC_PULSE_OXIMETER 3136 /**
#define BLE_APPEARANCE_PULSE_OXIMETER_FINGERTIP 3137 /**
#define BLE_APPEARANCE_PULSE_OXIMETER_WRIST_WORN 3138 /**
#define BLE_APPEARANCE_GENERIC_WEIGHT_SCALE 3200 /**
#define BLE_APPEARANCE_GENERIC_OUTDOOR_SPORTS_ACT 5184 /**
#define BLE_APPEARANCE_OUTDOOR_SPORTS_ACT_LOC_DISP 5185 /**
#define BLE_APPEARANCE_OUTDOOR_SPORTS_ACT_LOC_AND_NAV_DISP 5186 /**
#define BLE_APPEARANCE_OUTDOOR_SPORTS_ACT_LOC_POD 5187 /**
#define BLE_APPEARANCE_OUTDOOR_SPORTS_ACT_LOC_AND_NAV_POD 5188 /**
//设置图标信息
sd_ble_gap_appearance_set(uint16_t appearance);


GAP 连接参数

BLE功耗低的原因之一就是仅在数据收发时开启射频电路&＃xff0c;这里有一个重要的参数----连接间隔 connection interval&＃xff0c;它约定了BLE双方碰头时间&＃xff0c;当主从机配对连接后&＃xff0c;每隔一段时间&＃xff0c;主机会向从机发送一包数据&＃xff0c;从机接到主机数据后发一包数据给主机&＃xff0c;用与主从机之间数据交换和连接状态判断&＃xff08;没有数据包会发生连接超时&＃xff0c;断开连接&＃xff09;。当然连接间隔是可以根据需要灵活修改的&＃xff08;7.5ms – 4000ms&＃xff09;

#define MIN_CONN_INTERVAL MSEC_TO_UNITS(100, UNIT_1_25_MS) /**
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(200, UNIT_1_25_MS) /**
#define SLAVE_LATENCY 0 /**
#define CONN_SUP_TIMEOUT MSEC_TO_UNITS(4000, UNIT_10_MS) /**
/**&＃64;brief Function for the GAP initialization.
*
* &＃64;details This function sets up all the necessary GAP (Generic Access Profile) parameters of the
* device including the device name, appearance, and the preferred connection parameters.
*/
static void gap_params_init(void)

ret_code_t err_code;
ble_gap_conn_params_t gap_conn_params;
memset(&gap_conn_params, 0, sizeof(gap_conn_params));
gap_conn_params.min_conn_interval &＃61; MIN_CONN_INTERVAL;
gap_conn_params.max_conn_interval &＃61; MAX_CONN_INTERVAL;
gap_conn_params.slave_latency &＃61; SLAVE_LATENCY;
gap_conn_params.conn_sup_timeout &＃61; CONN_SUP_TIMEOUT;
err_code &＃61; sd_ble_gap_ppcp_set(&gap_conn_params);
APP_ERROR_CHECK(err_code);



其中图中M为主机发送的数据包&＃xff0c; S为从机发送的数据包&＃xff0c;当潜伏周期为0时&＃xff0c;每个主机数据包从机均需要应答&＃xff0c;而当潜伏周期为3时&＃xff0c;从机可以跳过三个数据包应答一次主机。

GAP 发射功率

nrf52832 支持-40dBm, -20dBm, -16dBm, -12dBm, -8dBm, -4dBm, 0dBm, &＃43;3dBm , &＃43;4dBm.9种功率,通过sd_ble_gap_tx_power_set 函数进行设置.

/**&＃64;brief GAP TX Power roles.
*/
enum BLE_GAP_TX_POWER_ROLES

BLE_GAP_TX_POWER_ROLE_ADV &＃61; 1, /**<广播角色. */
BLE_GAP_TX_POWER_ROLE_SCAN_INIT &＃61; 2, /**<扫描和发起者角色. */
BLE_GAP_TX_POWER_ROLE_CONN &＃61; 3, /**<连接角色. */
;
/**&＃64;brief Set the radio&＃39;s transmit power.
*
* &＃64;param[in] role The role to set the transmit power for, see &＃64;ref BLE_GAP_TX_POWER_ROLES for
* possible roles.
* &＃64;param[in] handle The handle parameter is interpreted depending on role:
* - If role is &＃64;ref BLE_GAP_TX_POWER_ROLE_CONN, this value is the specific connection handle.
* - If role is &＃64;ref BLE_GAP_TX_POWER_ROLE_ADV, the advertising set identified with the advertising handle,
* will use the specified transmit power, and include it in the advertising packet headers if
* &＃64;ref ble_gap_adv_properties_t::include_tx_power set.
* - For all other roles handle is ignored.
* &＃64;param[in] tx_power Radio transmit power in dBm (see note for accepted values).
*
* &＃64;note Supported tx_power values: -40dBm, -20dBm, -16dBm, -12dBm, -8dBm, -4dBm, 0dBm, &＃43;3dBm and &＃43;4dBm.
* &＃64;note The initiator will have the same transmit power as the scanner.
* &＃64;note When a connection is created it will inherit the transmit power from the initiator or
* advertiser leading to the connection.
*
* &＃64;retval ::NRF_SUCCESS Successfully changed the transmit power.
* &＃64;retval ::NRF_ERROR_INVALID_PARAM Invalid parameter(s) supplied.
* &＃64;retval ::BLE_ERROR_INVALID_ADV_HANDLE Advertising handle not found.
* &＃64;retval ::BLE_ERROR_INVALID_CONN_HANDLE Invalid connection handle supplied.
*/
SVCALL(SD_BLE_GAP_TX_POWER_SET, uint32_t, sd_ble_gap_tx_power_set(uint8_t role, uint16_t handle, int8_t tx_power));


连接参数初始化

在NRF52832协议栈中&＃xff0c;当主从机连接后&＃xff0c;如果想要修改GAP连接参数&＃xff0c;需要从机向主机发起连接参数更新请求&＃xff08;从机发起连接参数请求前&＃xff0c;使用主机的连接参数&＃xff09;&＃xff0c;主机收到连接参数更新请求后&＃xff0c;如果同意更新GAP参数则会更改自身GAP参数然后向从机发送同意连接参数更新。从机是何时发起连接参数更新请求&＃xff1f;

ret_code_t ble_conn_params_init(const ble_conn_params_init_t * p_init)

ret_code_t err_code;
VERIFY_PARAM_NOT_NULL(p_init);
m_conn_params_config &＃61; *p_init;
m_conn_params_config.p_conn_params &＃61; &m_preferred_conn_params;
if (p_init->p_conn_params !&＃61; NULL)

// Set the connection params in stack.
err_code &＃61; sd_ble_gap_ppcp_set(p_init->p_conn_params);
if (err_code !&＃61; NRF_SUCCESS)

return err_code;

m_preferred_conn_params &＃61; *p_init->p_conn_params;

else

// Get the (default) connection params from stack.
err_code &＃61; sd_ble_gap_ppcp_get(&m_preferred_conn_params);
if (err_code !&＃61; NRF_SUCCESS)

return err_code;


//lint -save -e681 "Loop not entered" when NRF_BLE_CONN_PARAMS_INSTANCE_COUNT is 0
for (uint32_t i &＃61; 0; i < NRF_BLE_CONN_PARAMS_INSTANCE_COUNT; i&＃43;&＃43;)

ble_conn_params_instance_t * p_instance &＃61; &m_conn_params_instances[i];
instance_free(p_instance);
p_instance->timer_id &＃61; &m_timer_data[i];
err_code &＃61; app_timer_create(&p_instance->timer_id,
APP_TIMER_MODE_SINGLE_SHOT,
update_timeout_handler);
if (err_code !&＃61; NRF_SUCCESS)

return NRF_ERROR_INTERNAL;


//lint -restore
return NRF_SUCCESS;

/**&＃64;brief Function for initializing the Connection Parameters module.
*/
static void conn_params_init(void)

ret_code_t err_code;
ble_conn_params_init_t cp_init;
memset(&cp_init, 0, sizeof(cp_init));
cp_init.p_conn_params &＃61; NULL;
cp_init.first_conn_params_update_delay &＃61; FIRST_CONN_PARAMS_UPDATE_DELAY; //主从机连接后&＃xff0c;延时多长时间进行第一次参数更新请求
cp_init.next_conn_params_update_delay &＃61; NEXT_CONN_PARAMS_UPDATE_DELAY; //延时多长时间进行第二次参数更新请求
cp_init.max_conn_params_update_count &＃61; MAX_CONN_PARAMS_UPDATE_COUNT; //最大尝试更新次数
cp_init.start_on_notify_cccd_handle &＃61; BLE_GATT_HANDLE_INVALID; //GAP 通知服务句柄
cp_init.disconnect_on_fail &＃61; false; //更新不成功自动断开连接&＃xff1f;
cp_init.evt_handler &＃61; on_conn_params_evt;
cp_init.error_handler &＃61; conn_params_error_handler;
err_code &＃61; ble_conn_params_init(&cp_init);
APP_ERROR_CHECK(err_code);



ble_conn_params_init 函数其实就是创建了几个软件定时器&＃xff0c;在软件定时器超时回调函数 update_timeout_handler 中发送参数更新请求。ble_conn_params.c中注册了一个观察者回调函数&＃xff0c;当主从机连接成功后&＃xff0c;会在 on_connect(p_ble_evt); 函数中开启参数更新软件定时器。

/**
* &＃64;brief Function for handling BLE events.
*
* &＃64;param[in] p_ble_evt Event received from the BLE stack.
* &＃64;param[in] p_context Context.
*/
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)

switch (p_ble_evt->header.evt_id)

case BLE_GAP_EVT_CONNECTED:
on_connect(p_ble_evt);
break;
case BLE_GAP_EVT_DISCONNECTED:
on_disconnect(p_ble_evt);
break;
case BLE_GATTS_EVT_WRITE:
on_write(p_ble_evt);
break;
case BLE_GAP_EVT_CONN_PARAM_UPDATE:
on_conn_params_update(p_ble_evt);
break;
default:
// No implementation needed.
break;




GATT 初始化

nrf52832中对GATT初始化主要是为了初始化MTU长度。

MTU: 最大传