本文将详细介绍微信小程序的蓝牙开发流程（附源码）
准备：
微信只支持低功耗蓝牙也就是蓝牙4.0，普通的蓝牙模块是用不了的，一定要注意。

蓝牙可以连TTL接到电脑上，再用XCOM调试

一开始定义的变量

var deviceId;
var i=0;
var serviceId=[];
var characteristicId=[];

蓝牙开发流程：
1.打开蓝牙适配器

2.搜索周围蓝牙

3.获取搜索过程中所搜索到的设备信息

4.连接想要连接的设备

5.获取服务、特征值

6.写数据、读数据

具体实现：
1.打开蓝牙适配器

wx.openBluetoothAdapter({
success: function(res) {
console.log(res,"success")
},
fail: function (res) {
console.log("fail")
},
})

2.适配器打开后可以开始搜索蓝牙设备了

wx.startBluetoothDevicesDiscovery({
services: [],
success: function (res) {
console.log(res)
},
fail: function (res) {
console.log("fail")
},
})
    sevices里不要填参数，要不然只能搜索特定的设备

3.搜索一小段时间后可以查看搜索到的设备，一般时间很短，1s都不用，搜不到可以多等等

wx.getBluetoothDevices({
success: function (res) {
console.log(res)
i=0;
while (res.devices[i]) {
console.log(i);
console.log(res.devices[i].name,res.devices[i].deviceId);
if(res.devices[i].name=='YahBoom_BL'){
deviceId=res.devices[i].deviceId;
console.log(deviceId);
}
i++;
}
}
})
这一步将所有搜索到的设备的名字和ID输出，并将名字为'YahBoom_BL'的设备的Id存到deviceId里去，这个设备就是我所需要使用的

4.现在我们可以获取一个特定设备的所有服务了

wx.getBLEDeviceServices({
deviceId: deviceId,
success: function(res) {
console.log(res.services);
i=0;
while(res.services[i]){
serviceId[i]=res.services[i].uuid;
console.log(serviceId[i]);
i++;
}
},
})
这一步我们获取YahBoom_BL的所有服务并储存到serviceId数组里去

5.现在我们可以针对一个特定服务查看这个服务所支持的操作

wx.getBLEDeviceCharacteristics({
deviceId: deviceId,
serviceId: serviceId[1],
success: function (res) {
i=0;
while(res.characteristics[i]){
characteristicId[i]=res.characteristics[i].uuid;
console.log(characteristicId[i]);
i++;
}
}
})
在这里我们获取YahBoom_BL的第二个服务（第一个服务下标为0，选第二个因为我的设备的第二个服务的第一个特征值支持notif、read、write，可以把一个服务的所有特征值打印出来查看）的特征值，并将特征值ID存到characteristicId数组里去

6.开启notify并读取蓝牙发过来的数据，开启这个后我们就能实时获取蓝牙发过来的值了

wx.notifyBLECharacteristicValueChange({
state: true,
deviceId: deviceId,
serviceId: serviceId[1],
characteristicId: characteristicId[0],
success: function (res) {
console.log('notifyBLECharacteristicValueChange success', res.errMsg)
}
})
function ab2hex(buffer) {
var hexArr = Array.prototype.map.call(
new Uint8Array(buffer),
function(bit) {
return ('00' + bit.toString(16)).slice(-2)
}
)
return hexArr.join('');
}
wx.onBLECharacteristicValueChange(function (res) {
console.log('characteristic value comed:', ab2hex(res.value))
})
这里第一个函数是开启notify服务，deviceId、serviceId、characteristicId都是之前我们获取的，第二个函数是将bufferArray类型转为string类型，因为buffer不能直接在console.log里输出，会显示null，第三个函数就是监听蓝牙发送过来的值了，蓝牙每次发送一个值，都会回调这个函数，res.value就是一个bufferArray类型，存的是发送过来的值

7.写数据到蓝牙

let buffer = new ArrayBuffer(3)
let dataView = new DataView(buffer)
dataView.setUint8(1, 100)

wx.writeBLECharacteristicValue({
deviceId: deviceId,
serviceId: serviceId[1],
characteristicId: characteristicId[0],
value: buffer,
success: function (res) {
console.log('writeBLECharacteristicValue success', res.errMsg)
}
})
传数据给蓝牙时只能用buffer类型，let buffer = new ArrayBuffer(3)这句话定义一个三个长度的buffer，dataView.setUint8(1, 100)这句话将第一个值设置为100，所以传递过去的值就是00 64 00 （十六进制）

附录（直接复制粘贴就能运行）

JS源码：

var app = getApp();
var deviceId;
var i=0;
var serviceId=[];
var characteristicId=[];
Page({
data: {

},
onLoad:function(){
wx.onBluetoothAdapterStateChange(function (res) {
console.log('adapterState changed, now is', res)
})

},

openadapter:function(){
wx.openBluetoothAdapter({
success: function(res) {
console.log(res,"success")
},
fail: function (res) {
console.log(res,"fail")
},
})
// wx.getBluetoothAdapterState({
// complete: function (res) {
// console.log("currentstate:",res)
// }
// })
},
closeadapter: function () {
wx.closeBluetoothAdapter({
success: function (res) {
console.log(res, "success")
},
fail: function (res) {
console.log(res, "fail")
},
})
// wx.getBluetoothAdapterState({
// complete: function (res) {
// console.log("currentstate:", res)
// }
// })
},

opendiscovery:function(){
wx.startBluetoothDevicesDiscovery({
services: [],
success: function (res) {
console.log(res)
},
fail: function (res) {
console.log(res, "fail")
},
})
},

closediscovery:function(){
wx.stopBluetoothDevicesDiscovery({
success: function (res) {
console.log(res)
},
fail: function (res) {
console.log(res, "fail")
},
})
},

getdevice:function(){
function ab2hex(buffer) {
var hexArr = Array.prototype.map.call(
new Uint8Array(buffer),
function (bit) {
return ('00' + bit.toString(16)).slice(-2)
}
)
return hexArr.join('');
}
wx.getBluetoothDevices({
success: function (res) {
console.log(res)
i=0;
while (res.devices[i]) {
console.log(i);
console.log(res.devices[i].name,res.devices[i].deviceId);
if(res.devices[i].name=='YahBoom_BL'){
deviceId=res.devices[i].deviceId;
console.log(deviceId);
}
i++;
}
}
})
},

getconnecteddevice:function(){
wx.getConnectedBluetoothDevices({
//services:[],
success: function (res) {
console.log(res)
}
})
},
connecteddevice:function(){
wx.createBLEConnection({
deviceId: deviceId,
success: function(res) {
console.log(res);
},
})
},
getservice:function(){
wx.getBLEDeviceServices({
deviceId: deviceId,
success: function(res) {
console.log(res.services);
i=0;
while(res.services[i]){
serviceId[i]=res.services[i].uuid;
console.log(serviceId[i]);
i++;
}
},
})
},
getcharacteristics:function(){
wx.getBLEDeviceCharacteristics({
deviceId: deviceId,
serviceId: serviceId[0],
success: function (res) {
console.log('device getBLEDeviceCharacteristics:', res.characteristics)
}
})
wx.getBLEDeviceCharacteristics({
deviceId: deviceId,
serviceId: serviceId[1],
success: function (res) {
i=0;
while(res.characteristics[i]){
characteristicId[i]=res.characteristics[i].uuid;
console.log(characteristicId[i]);
i++;
}
}
})
},
startread:function(){
wx.readBLECharacteristicValue({
deviceId: deviceId,
serviceId: serviceId[1],
characteristicId: characteristicId[0],
success: function (res) {
console.log('readBLECharacteristicValue:', res.errCode)
}
})
},
startnotify:function(){
wx.notifyBLECharacteristicValueChange({
state: true,
deviceId: deviceId,
serviceId: serviceId[1],
characteristicId: characteristicId[0],
success: function (res) {
console.log('notifyBLECharacteristicValueChange success', res.errMsg)
}
})
function ab2hex(buffer) {
var hexArr = Array.prototype.map.call(
new Uint8Array(buffer),
function(bit) {
return ('00' + bit.toString(16)).slice(-2)
}
)
return hexArr.join('');
}
wx.onBLECharacteristicValueChange(function (res) {
console.log('characteristic value comed:', ab2hex(res.value))
})
},
startwrite:function(){
let buffer = new ArrayBuffer(3)
let dataView = new DataView(buffer)
dataView.setUint8(1, 100)

wx.writeBLECharacteristicValue({
deviceId: deviceId,
serviceId: serviceId[1],
characteristicId: characteristicId[0],
value: buffer,
success: function (res) {
console.log('writeBLECharacteristicValue success', res.errMsg)
}
})
}

})

WXML源码：

<button bindtap='openadapter'>打开适配器</button>
<button bindtap='closeadapter'>关闭适配器</button>
<button bindtap='opendiscovery'>开始搜索</button>
<button bindtap='closediscovery'>关闭搜索</button>
<button bindtap='getdevice'>获取设备</button>
<button bindtap='getconnecteddevice'>获取已连接设备</button>
<button bindtap='connecteddevice'>连接我的设备</button>
<button bindtap='getservice'>获取服务</button>
<button bindtap='getcharacteristics'>获取特征值</button>
<button bindtap='startread'>读取值</button>
<button bindtap='startnotify'>开启notify</button>
<button bindtap='startwrite'>写数据</button>