Embedded development: five challenges in wireless update using MCU

　　 The ability to update embedded systems using boot loaders is an important skill to master . Despite all the efforts to develop embedded systems , But either mistakes are found at the scene , Either the end user requires additional functionality . To update firmware wirelessly in the field or remotely , Embedded system must have on-board boot loader . For the wireless update embedded system as part of the Internet of things , Embedded development teams face five key challenges .

　　 Challenge 1 – Code size

　　 Microcontroller based applications used to be very small , Only up to 8 To 16 KB. Modern microcontrollers can provide developers with more than 1024 KB Application code space . Despite explosive growth in capacity and functionality , But for embedded programmers who want to update firmware wirelessly , Code size is the first challenge .

　　 One of the code size challenges is that microcontrollers typically do not have an onboard file system for running application code , This is with running Linux Based on the CPU Different systems . Because the file does not exist , The target file is continuously placed in memory by the linker . Minor adjustments to the application may cause the entire flash memory space to be updated ! To prevent such a disaster , Developers need to think ahead about partitioning memory , And predict which areas of the code base might need to be modified . The result may be inefficient use of on-board flash memory , And it increases the complexity of the system .

　　 Challenge 2 – bandwidth

　　 Usually , When embedded developers consider the bandwidth associated with the boot loader , Bandwidth is used to determine the maximum flash time required to update the application . Updating embedded systems wirelessly may add some additional challenges .

　　 The first challenge involves boot loaders that need to work on wireless links , This may incur costs associated with transmitting and receiving data . in many instances , Wireless updates may be made via WIFI Or Ethernet , But what about mobile devices that use cellular data links ? Consider a single embedded system , A single... Required to update the system may be ignored MB Application code , however , What happens when millions of devices need to be updated ? Just launching an update can be quite costly .

　　 The engineer who developed the boot loader , Especially engineers who perform updates wirelessly , You need to find a way to compress the application image , To minimize the amount of data transmitted over the air . Compression can be performed in a number of ways , Or if the developer partitions the flash memory space on a per object basis , You can even use diff file .

　　

　　 Challenge 3– robustness

　　 One of the temptations that many embedded development teams face is to use the boot loader solution provided by the chip manufacturer . The problem with chipmaker solutions is that they are often located in places that cannot be customized ROM In the space . what's more , be based on ROM The boot loader for is usually just functional code . The function code can perform the purpose under controlled conditions , But it doesn't apply to the production environment where anything happens .

　　 Robustness needs to be built into the boot loader solution from the start . The boot loader shall have the ability to verify the integrity of the on-board application . The boot loader should be able to detect failed firmware updates and roll back to the original application , Instead of making the system brick . In the production environment , There are many events that can disrupt the system , But a properly designed boot loader will be powerful enough , They can be handled smoothly , The end user is not aware of the problem .

　　 Challenge 4 – Security

　　 Many microcontroller based boot loaders ignore security , This is a key challenge for developers performing wireless updates . One of the simplest security measures that embedded developers can take is to simply lock the flash memory system , Developers performing wireless updates may consider encrypting their application images , To prevent anyone from gaining insight into proprietary firmware , Even reverse engineering and Intrusion systems . The wireless boot loader shall have a built-in method for verifying the update process .

　　 Challenge 5 – version management

　　 Managing firmware versions that will be distributed to potentially millions of devices is not easy . Strangely enough , Firmware updates will not be pushed all at once , It is pushed in batches . what's more , There may be different versions of hardware at some point , It is even possible to provide different application sets for different end users . Tracking and ensuring that firmware is successfully rolled out can be a major challenge .

　　 Conclusion

　　 Boot loaders are usually ignored before the end of the development cycle , But they play a key role in embedded systems . The five challenges presented here are just a few of the challenges faced by embedded developers , They are using microcontrollers to develop connection systems .