10. Tencent cloud IOT device side learning - firmware upgrade

The main purpose of this series is to record the learning notes of Tencent cloud Internet of things device , And on the device side SDK Make a supplementary explanation .

brief introduction

Firmware upgrade

Firmware upgrade is basically a necessary function of IOT devices , The firmware upgrade function is in IoT Hub and IoT Explorer All supported . In fact, it can be seen as two parts ：

• Control messages ： Interact with Tencent cloud IOT platform , This includes getting firmware download information , Realize the logic of interaction
• Firmware data ： Interact with Tencent cloud object storage platform , Pull the actual firmware data

The general process is as follows ：

Firmware upgrade process

Development considerations

Firmware upgrade is a very sensitive operation , To achieve a stable firmware upgrade, you generally need to do the following ：

• Firmware verification ： Developers need to verify the downloaded firmware on the device side （ Not only here md5 check , The equipment supplier's own calibration shall also be included , because md5 Only the correctness of the document can be guaranteed , There is no guarantee that the firmware itself is faulty ）, To avoid accidents .
• Breakpoint continuation ： For weak network scenarios or devices with large firmware , You need to do a good job of breakpoint continuation , Ensure the success rate of downloading , That is to save the breakpoint information in the corresponding storage after each download （ It's usually flash in , There are also placed in ram in , Only for breakpoints in the boot scenario ）.SDK This feature is already supported .
• Firmware backup ： Routinely , The firmware to be upgraded is stored in the backup area , When the equipment is powered on , Read the firmware from the backup area through the program to upgrade , Because the backup area is read-only , So even if there are abnormal conditions such as power failure in the midway , It can also ensure the availability of the equipment .
• Multi firmware ： In fact, there is no essential difference between multi firmware and single firmware , Because the firmware upgrade is for files , Information can be added to the file to split a single file into multiple firmware . Of course , Another way is to use resources to download （ Subsequent articles will mention ）, This is also one of the important features supported by Tencent cloud Internet of things .