Connect a device to IoT Platform with the device-side Link SDK - IoT Platform

Use the data_model_basic_demo sample program to simulate a street lamp device and connect it to IoT Platform through the C SDK.

Important notes

The steps in this topic are performed as a regular user. If an operation requires administrative permissions, prefix the command with sudo.

Prepare the development environment

The device-side C SDK runs on Linux. Compile it in a 64-bit Ubuntu 16.04 environment.
Required software:

make 4.1 or later, gcc 5.4.0 or later.

Install command:
```
sudo apt-get install -y build-essential make gcc
```

Procedure

Download the C SDK for devices: C SDK 4.x.

Unzip the C SDK file and modify the device certificate information.

Download data_model_basic_demo.c and use it to replace the file in \LinkSDK\demos. Update the following parameters:

char *product_key       = "a2***";
char *device_name       = "device1";
char *device_secret     = "8c684ef***";
...
...
char  *mqtt_host = "a2***.iot-as-mqtt.cn-shanghai.aliyuncs.com";

Parameter	Example	Description
mqtt_host	New public instances:`iot-cn-*.mqtt.iothub.aliyuncs.com` Old public instances:`a2*.iot-as-mqtt.cn-shanghai.aliyuncs.com`	The MQTT ingest endpoint for the device. New public instances: On the Instance Details page, click View Development Configurations. The endpoint appears on the Development Configurations panel. Old public instances: The endpoint format is`${YourProductKey}.iot-as-mqtt.${YourRegionId}.aliyuncs.com`. View instance endpoints.
product_key	`a2***`	The device certificate saved when you added the device. You can also view the certificate on the Device Details page in the IoT Platform console. Obtain a device certificate.
device_name	`device1`
device_secret	`8c684ef***`

On the Linux virtual machine, install the required software.
```
sudo apt-get install -y build-essential make gcc
```
Upload the modified LinkSDK directory to your Linux virtual machine.
In the SDK root directory /LinkSDK, run the make command to compile the sample program.
```
make clean
make
```
The compiled binary data-model-basic-demo is in ./output.

Run the sample program.

./output/data-model-basic-demo

Expected output:

root@xxx:~/linkSDK# ./output/data-model-basic-demo
[1637041632.700][LK-0313] MQTT user calls aiot_mqtt_connect api, connect
[1637041632.700][LK-032A] mqtt host: axxx.iot-as-mqtt.cn-shanghai.aliyuncs.com
[1637041632.700][LK-0317] user name: device1&axxx,0
[1637041632.700][LK-0318] password: 86761xxx¥21D
establish tcp connection with server(host='axxx.iot-as-mqtt.cn-shanghai.aliyuncs.com', port=[443])
success to establish tcp, fd=3
local port: 35604
[1637041632.711][LK-1000] establish mbedtls connection with server(host='axxx.iot-as-mqtt.cn-shanghai.aliyuncs.com', port=[443])
[1637041632.766][LK-1000] success to establish mbedtls connection, (cost 45252 bytes in total, max used 47988 bytes)
[1637041632.811][LK-0313] MQTT connect success in 108 ms
AIOT_MQTTEVT_CONNECT
[1637041632.811][LK-0309] pub: /sys/axxx/device1/thing/event/property/post

[LK-030A] > 7B 22 69 64 22 3A 22 31  22 2C 22 76 65 72 73 69 | {"id":"1","versi
[LK-030A] > 6F 6E 22 3A 22 31 2E 30  22 2C 22 70 61 72 61 6D | on":"1.0","param
[LK-030A] > 73 22 3A 7B 22 4C 69 67  68 74 43 75 72 72 65 6E | s":{"LightCurren
[LK-030A] > 74 22 3A 20 31 2E 35 7D  2C 22 73 79 73 22 3A 7B | t": 1.5},"sys":{
[LK-030A] > 22 61 63 6B 22 3A 31 7D  7D                       | "ack":1}}

[1637041632.833][LK-0309] pub: /sys/axxx/device1/thing/event/property/post_reply

[LK-030A] < 7B 22 63 6F 64 65 22 3A  32 30 30 2C 22 64 61 74 | {"code":200,"dat
[LK-030A] < 61 22 3A 7B 7D 2C 22 69  64 22 3A 22 31 22 2C 22 | a":{},"id":"1","
[LK-030A] < 6D 65 73 73 61 67 65 22  3A 22 73 75 63 63 65 73 | message":"succes
[LK-030A] < 73 22 2C 22 6D 65 74 68  6F 64 22 3A 22 74 68 69 | s","method":"thi
[LK-030A] < 6E 67 2E 65 76 65 6E 74  2E 70 72 6F 70 65 72 74 | ng.event.propert
[LK-030A] < 79 2E 70 6F 73 74 22 2C  22 76 65 72 73 69 6F 6E | y.post","version
[LK-030A] < 22 3A 22 31 2E 30 22 7D                           | ":"1.0"}

[1637041632.833][LK-0A08] DM recv generic reply
demo_dm_recv_handler, type = 0
msg_id = 1, code = 200, data = {}, message = success

In the IoT Platform console, go to the Public Instance page. Verify the device status.
- Choose Device Management > Devices. On the Devices page, enter device1 in the DeviceName search box to find the target device. Verify that the device status is Online.
- Click View in the Actions column. On the Device Details page, click the TSL Data tab and then Running Status.
  
  The data_model_basic_demo.c sample reports the operating current value.
  
  On the Running Status tab, the Operating Current property displays a value of 1.5 A, indicating that the device has successfully reported this property value.

What to do next

You can now subscribe to device messages from the server.