https://www.cnblogs.com/yangfengwu/p/11482905.html
On a test of this section is the Wi-Fi test GPRS
See the name to know, simply means that the microcontroller using AT commands control module for communication control MQTT
This section is STM32 + GPRS (AT command) to achieve communication control MQTT:
First, download the program STM32
1, a way, serial download (download other way in the final supplement)
Adjusting the position of the toggle switch ① → → 3.3V and short BOOT0 reset STM32
② Open download software, download program
Selecting the right serial port
Remove shorted, reset the microcontroller
① phone card
② antenna
③ to adjust the toggle switch, and so the GPRS communication STM32
Open the phone APP
Download APP (APP purchase to secure the articles to get, only learned a small micro-channel Programming can be able to understand the source code, knowledge involves a little more)
Scan code download
Note: Only when normal communication MQTT description (just found out that you can insert video ....)
then
Finally, talk about the program
First look at the official documentation
Check yourself
On an overall code and the same, there are several places to talk about
In order to shorten the time it is actually transmitted command, as long as the received corresponding data is determined, and transmits the next instruction immediately
However, to be safe, middle 500ms delay
Further, with the main function inside a serial callback
If you want to know how to write the callback function, you can look at this https://www.cnblogs.com/yangfengwu/p/11112014.html
Get IMEI, I feel so get IMEI safer.
Note: This code does not cook, reconnection of it!
In fact, with GPRS MQTT achieve a place of contradictions.
MQTT heartbeat packet is determined by the device is not online, the heartbeat packet data C0,00
But then, speaking for GPRS, heartbeat packet time is too short ... we need more traffic
Too long, then you can not know in time not dropped off ....