【安信可BW16-Kit】AT指令体验之MQTT
<div class='showpostmsg'># 【安信可BW16-Kit】AT指令体验之MQTT我用emqx在本地搭建了一个MQTT服务器，搭建过程可以查看官网搭建方式
# 01 连接Wifi
连接WiFi请看上篇帖子
# 02 配置MQTT
命令： ```AT+MQTT=<key>,<data>```
参数2：```<data>```设置的参数
参数1：```<key>```MQTT参数。
1：设置连接的域名或 IP
2：设置服务器端口号
3：设置连接方式(暂时默认 1：使用tcp连接)
4：设置客户端ID
5：设置用户名(最大长度63字节)
6：设置登录密码(最大长度63字节)
7：设置遗嘱消息
格式为
```c
AT+MQTT=7,<LWT_topic>,<LWT_qos>,<LWT_Retained>,<LWTpayload>
LWT_topic：遗嘱主题(不需要遗嘱这里设置为空)
LWT_qos：遗嘱 QOS(0/1/2)
LWT_Retained：遗嘱 retained(0/1)
LWTpayload：遗嘱消息内容
```
## 示例
```shell
AT+MQTT=1,192.168.1.9 // 设置MQTT服务器URL
flash save ok
AI_HalWriteFlash success
OK
After do cmd, available heap 120224
AT+MQTT=2,1883 // 设置MQTT服务器端口
flash save ok
AI_HalWriteFlash success
OK
After do cmd, available heap 120224
AT+MQTT=3,1 // 设置连接方式 TCP
don't need save flash
OK
After do cmd, available heap 120224
AT+MQTT=4,bw16 // 设置客户端ID
flash save ok
AI_HalWriteFlash success
OK
After do cmd, available heap 120224
AT+MQTT=5, // 设置用户名 我这里为空
cmd format error
+MQTT:3
ERROR
After do cmd, available heap 120224
AT+MQTT=6, // 设置密码 我这里为空
cmd format error
+MQTT:3
ERROR
After do cmd, available heap 120224
AT+MQTT? // 查询 MQTT 连接和配置情况
+MQTT:0,192.168.1.9,1883,1,bw16,,,,0,0,
OK
After do cmd, available heap 120224
AT+MQTT // 连接MQTT
not set LWT
MQTT connect config
host:192.168.1.9:1883
username:
password:
clientID:bw16
use tcp
OK
After do cmd, available heap 103680
start MQTT connect
host:192.168.1.9:1883
username:
password:
clientID:bw16
willFlag:0
use tcp
addr=192.168.1.9
Set mqtt status to MQTT_CONNECT
send mqtt connect cmd success
Read packet type is CONNACK
recive MQTT Connected ack
// 连接成功
```
此时，后台会有对应客户端连接
# 03 订阅消息
命令： ```AT+MQTTSUB=<topic>,<qos>```
参数1：```<topic>```要订阅的主题。(最多订阅四个主题)
参数2：```<qos>```qos 等级(0,1,2)。
```c
AT+MQTTSUB=topic,0
Set mqtt status to MQTT_SUBTOPIC
send topic topic cmd success,wait ack
Read packet type is SUBACK
wait subscribe ack success,grantedQoS=0
Set mqtt status to MQTT_RUNNING
recive Subscribe ack,subscribe success
OK
After do cmd, available heap 103136
```
后台显示
## 当订阅消息后，该主题有消息后，就会通过串口显示
### 其他客户端发送消息
### BW16收到主题
```c
Message arrived
+EVENT:MQTT_SUB,topic,18,{ "msg": "hello" }
```
# 04 发布消息
命令： ```AT+MQTTPUB=<topic>,<qos>,<Retained>,<payload>```
参数1：```<topic>```要发布的主题
参数2：```<qos>```qos 等级(0,1,2)。
参数3：```<Retained>```0：普通消息 1：保留消息
参数4：```<payload>```数据内容(最大长度为1024个字节)
```c
AT+MQTTPUB=topic,0,0,hello bw16 // 发送消息
Publish Topic topic:0
Qos0 not need Ack
OK
After do cmd, available heap 103136
Read packet type is PUBLISH
Message arrived
+EVENT:MQTT_SUB,topic,11,hello bw16 // 接收消息
```
### 客户端显示
# 05取消订阅
命令： ```AT+MQTTUNSUB=<topic>```
参数1：```<topic>```要取消订阅的主题
```c
AT+MQTTUNSUB=topic
Read packet type is UNSUBACK
topic:topic set AI_MQTT_RECIVE_UNSUBACK
recive UnSubscribe ack,UnSubscribe success
OK
After do cmd, available heap 103200
```
取消订阅成功
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