Tencent cloud Internet of things - gateway device experience

sdk Code, please click here obtain

Introduction to gateway equipment

about BLE、Zigbee and 485 And other devices that do not have direct access to the network , You need to access the gateway first , Then through the gateway proxy , Indirectly realize equipment access to Tencent Internet of things development platform IoT Explorer, The specific process framework is as follows ：

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So for a gateway device , Its basic Core functions yes ：

1. The gateway device itself is a fully functional Tencent cloud Internet of things development platform device . When not acting as a sub device agent , The gateway device can be operated as a device of an ordinary Tencent cloud Internet of things development platform . Many beginners have a misunderstanding , The gateway device is used to communicate with the proxy sub device , It has no business communicating with the platform , This understanding is totally wrong . for instance ： The gateway device can be a built-in 433 Wireless transceiver WiFi Smart socket , So as a socket , You should first have the function of socket switch , Then it's around the agent 433 Sub equipment online and offline .

2. Dynamic binding / Unbound sub equipment . Obviously , To bind and unbind a subdevice is to establish a topology relationship between the subdevice and the gateway . for instance ： Like children and fathers , A father may have two or three children , Then the father should be responsible for the child's clothing, food, housing and transportation , And for other unrelated children , Then the father is not responsible . Binding is equivalent to recognizing the parent-child relationship , Unbound is equivalent to severing the relationship between father and son . Yes, of course , In the real world , This parent-child relationship is not dynamic .

3. Agent sub equipment online and offline . for instance , When a Bluetooth gateway scans the Bluetooth broadcast of nearby sub devices and establishes a connection , You can notify the cloud platform through the gateway , There are currently sub devices active , Can go online . alike , When a sub device does not communicate with the Bluetooth gateway for a long time and sends a message without reply （ The specific offline strategy can be defined by yourself , Such as ： No sub device message is received within one hour and ping No sub equipment ） It can be considered that the current sub equipment is offline , So as to notify the offline sub equipment of the cloud platform .

4. Agent sub device communication . This function is the meaning of gateway equipment , The reason why gateway devices are needed is to proxy some data that cannot be directly connected to Internet of things devices . The gateway functions as a messenger here . The gateway device of Tencent cloud Internet of things is completely transparent to the messages of sub devices . for instance , We know that the attributes of Tencent cloud IOT development platform are through this mqtt topic To transmit ：

   • Data up Topic（ For publishing ）：$property/up/${productid}/${devicename}
   • Data down Topic（ To subscribe to ）：$property/down/${productid}/${devicename}

   Then the gateway will not reuse other topic To transmit the data of the sub equipment . let me put it another way , Binding between gateway product and sub product , Get the name of the sub device Topic After permission , Gateway devices can use sub devices Topic The agent sends and receives messages , At the same time, it can be debugged in the equipment - Check the communication information in the device log .

5. Agent sub device upgrade . The sub equipment also needs to update the firmware , Then the gateway device can pull down the firmware of the sub device from the background , Then send it to the sub equipment for upgrading , The whole process is shown in the figure ：

​ The same as ordinary equipment upgrade is , The whole upgrading process will follow the same process as that of ordinary equipment upgrading , Including version reporting 、 upgrade url Acquisition of and so on . however , Unlike ordinary device upgrades , The gateway device needs to save the firmware of the sub device before upgrading the sub device , Then through a private agreement （ It can be BLE zigbee 433 wait ） Send firmware to sub devices , After obtaining the upgrade status of the sub device , Then tell the cloud platform the result of the upgrade .

Specific gateway sub device topology relationship management protocol , Please click on here obtain .

Gateway device code design

Understand the functions of gateway devices , Let's think about how to design the gateway code , Then take a look at the device side of Tencent cloud Internet of things development platform sdk How to design the gateway function .

First , The number of sub devices is unknown , Some gateways may bring 3 Sub devices , Some may bring 30 individual , So when designing the gateway , You need to consider using the list function to manage sub devices . secondly , The gateway device must have the function of managing sub devices , That is, you can bind and unbind the child devices by proxy 、 Online and offline data communication, etc ; This requires maintaining the status of the sub equipment . Let's take a look at the structure of the gateway structure ：

typedef struct {
    
    void                     *mqtt_client; //  The gateway is based on mqtt Protocol to design , Here's a maintenance mqtt client 
    MQTTEventHandler          evt_handle;  //  Sub device event callback , Including binding / Unbundling   Notify the user when going online or offline 
    GatewayClientPriv        *priv;		  //  List of sub equipment 
    void                     *event_context; //  Callback Arguments 
    gateway_event_handle_cb_t gateway_evt_cb; //  Callback function 
    char                      gateway_pub_topic[MAX_SIZE_OF_GATEWAY_PUB_TOPIC];  // store gateway pub topic
} GatewayClient;

Let's take a look at the structure of the equipment ：

typedef enum {
    
    GATEWAY_SUBDEV_STATUS_ONLINE = 0,
    GATEWAY_SUBDEV_STATUS_OFFLINE,
} GatewaySubStatus;
//  Sub equipment structure 
typedef struct {
    
    DeviceInfo       dev_info;  //  Sub equipment information , Products including sub equipment ID  Equipment name, etc 
    GatewaySubStatus status;    //  Sub equipment status 
    int              is_binded; //  Is it bound 
    void            *node;      //  Linked list 
} GatewaySub;

Demo Log analysis

After the gateway equipment is powered on , Will use their own triple information to connect to Tencent cloud Internet of things development platform

INF|2022-04-20 17:48:42|mqtt_client.c|_qcloud_iot_mqtt_client_init(213): SDK_Ver: 4.0.0, Product_ID: 40FA6IALWV, Device_Name: gateway001
DBG|2022-04-20 17:48:42|qcloud_iot_tls_client.c|qcloud_iot_tls_client_connect(212): Setting up the SSL/TLS structure...
DBG|2022-04-20 17:48:42|qcloud_iot_tls_client.c|qcloud_iot_tls_client_connect(252): Performing the SSL/TLS handshake...
DBG|2022-04-20 17:48:42|qcloud_iot_tls_client.c|qcloud_iot_tls_client_connect(253): Connecting to /40FA6IALWV.iotcloud.tencentdevices.com/8883...
DBG|2022-04-20 17:48:43|qcloud_iot_tls_client.c|qcloud_iot_tls_client_connect(281): connected with /40FA6IALWV.iotcloud.tencentdevices.com/8883...
INF|2022-04-20 17:48:43|mqtt_client.c|IOT_MQTT_Construct(329): mqtt connect with id: C81F6 success
INF|2022-04-20 17:48:43|gateway_sample.c|main(303): Cloud Device Construct Success

After successful connection , Will subscribe to the gateway topic, Accept gateway downlink messages

DBG|2022-04-20 17:48:43|mqtt_client_subscribe.c|qcloud_iot_mqtt_subscribe(329): subscribe topic_name=$gateway/operation/result/40FA6IALWV/gateway001|packet_id=7041
INF|2022-04-20 17:48:43|gateway_sample.c|_mqtt_event_handler(75): subscribe success, packet-id=7041

send out describe_sub_devices news , Pull the topology relationship of the current gateway device from the cloud platform

DBG|2022-04-20 17:48:43|mqtt_client_publish.c|qcloud_iot_mqtt_publish(264): publish qos=0|packet_id=0|topic_name=$gateway/operation/40FA6IALWV/gateway001|payload={
    "type":"describe_sub_devices"}

Cloud platform reply :

DBG|2022-04-20 17:48:43|gateway_message_handle.c|gateway_message_handler(204): receive gateway message {
    "type":"describe_sub_devices","payload":{
    "devices":[{
    "product_id":"KRLT1QGQW5","device_name":"subdev001"},{
    "product_id":"KRLT1QGQW5","device_name":"subdev002"},{
    "product_id":"KRLT1QGQW5","device_name":"subdev003"},{
    "product_id":"KRLT1QGQW5","device_name":"subdev004"}]}}

At present, four sub devices have been bound to the gateway device .

Bind sub devices

Binding a sub device requires the gateway device to know the triple information of the sub device , This triple information can be obtained from the sub device , Or get it from the cloud platform . After getting the triple information , The gateway device needs to make a signature locally , Generate signature Field .

DBG|2022-04-20 17:48:43|gateway_sub_manage.c|IOT_Gateway_AddSub(332): Add 0x5647bd29fb70 KRLT1QGQW5:subdev006
DBG|2022-04-20 17:48:43|mqtt_client_publish.c|qcloud_iot_mqtt_publish(264): publish qos=0|packet_id=0|topic_name=$gateway/operation/40FA6IALWV/gateway001|payload={
    "type":"bind", 
 "payload":{
    "devices":[{
    "product_id":"KRLT1QGQW5","device_name":"subdev006","signature":"+j45scCBXI9qCDioF7m1NB4VuOU=","random":1603981974,"timestamp":1650448123,"signmethod":"hmacsha1","authtype":"psk"}]}}

Cloud platform reply :

DBG|2022-04-20 17:48:43|gateway_message_handle.c|gateway_message_handler(204): receive gateway message {
    "type":"bind","payload":{
    "devices":[{
    "result":0,"product_id":"KRLT1QGQW5","device_name":"subdev006"}]}}
INF|2022-04-20 17:48:43|gateway_message_handle.c|gateway_message_handler(211): Get type 2 from server
DBG|2022-04-20 17:48:43|gateway_message_handle.c|_gateway_down_array_result_parse(113): bind device KRLT1QGQW5:subdev006
INF|2022-04-20 17:48:43|gateway_sample.c|_mqtt_event_handler(111): gateway topology changed --- subdev KRLT1QGQW5:subdev006 change to binded

At the same time, we also received a message _mqtt_event_handler Event to notify a new device to join the topology relationship of the current gateway device . When this device goes online , You can communicate normally on behalf of this sub device .

Unbound sub equipment

Unbinding is easier , Directly send the list of devices to be unbound to the cloud platform , At the same time, the topology relationship should also be updated locally

DBG|2022-04-20 17:49:02|mqtt_client_publish.c|qcloud_iot_mqtt_publish(264): publish qos=0|packet_id=0|topic_name=$gateway/operation/40FA6IALWV/gateway001|payload={
    "type":"unbind",  "payload":{
    "devices":[{
    "product_id":"KRLT1QGQW5","device_name":"subdev006"}]}}

Cloud platform reply ：

DBG|2022-04-20 17:49:02|gateway_message_handle.c|gateway_message_handler(204): receive gateway message {
    "type":"unbind","payload":{
    "devices":[{
    "product_id":"KRLT1QGQW5","device_name":"subdev006","result":0}]}}
INF|2022-04-20 17:49:02|gateway_message_handle.c|gateway_message_handler(211): Get type 3 from server
DBG|2022-04-20 17:49:02|gateway_message_handle.c|_gateway_down_array_result_parse(117): del device KRLT1QGQW5:subdev006
INF|2022-04-20 17:49:02|gateway_sample.c|_mqtt_event_handler(111): gateway topology changed --- subdev KRLT1QGQW5:subdev006 change to unbinded

At the same time, I received a message _mqtt_event_handler Event to notify that a device is unbound , The messages of this device should not be sent through the gateway proxy in the future .

The agent sub equipment goes online

DBG|2022-04-20 17:48:45|mqtt_client_publish.c|qcloud_iot_mqtt_publish(264): publish qos=0|packet_id=0|topic_name=$gateway/operation/40FA6IALWV/gateway001|payload={
    "type":"online",  "payload":{
    "devices":[{
    "product_id":"KRLT1QGQW5","device_name":"subdev001"}]}}

After the current sub equipment is successfully online , You can interact with the cloud platform .

Agent sub equipment offline

DBG|2022-04-20 17:48:51|mqtt_client_publish.c|qcloud_iot_mqtt_publish(264): publish qos=0|packet_id=0|topic_name=$gateway/operation/40FA6IALWV/gateway001|payload={
    "type":"offline",  "payload":{
    "devices":[{
    "product_id":"KRLT1QGQW5","device_name":"subdev001"}]}}
DBG|2022-04-20 17:48:51|gateway_sample.c|_test_array_cb(243): test return 0
DBG|2022-04-20 17:48:51|gateway_message_handle.c|gateway_message_handler(204): receive gateway message {
    "type":"offline","payload":{
    "devices":[{
    "product_id":"KRLT1QGQW5","device_name":"subdev001","result":0}]}}
INF|2022-04-20 17:48:51|gateway_message_handle.c|gateway_message_handler(211): Get type 1 from server
INF|2022-04-20 17:48:51|gateway_sample.c|_mqtt_event_handler(117): gateway status changed --- subdev KRLT1QGQW5:subdev001 change to offline 

At the same time, I received a message _mqtt_event_handler Event to notify that a device is offline , The information of the sub equipment should not be reported to the gateway in the future .