BUSAT-1 On Board Software Design And Implementation

With the rapid development of space activities,micro/nano satellite space exploration has become a hot topic in the aerospace area according to its low cost.The outstanding characteristic of micro-nano satellite is small volume,light weight,low cost,short development cycle.To complete the complex mission,the micro/nano satellite put forward higher requirements for on board computer performance,software need to complete some of the task,which originally should be done by hardware.So,on board software is more and more important,and has become one of the keys to complete the detection task.The on board integrated electronic system and the function of the electronic device of the hardware environment were introduced in this paper first.BM3109 chip is the first-use in the field of micro satellite.Then the software engineering development models were analyzed,and a suitable model for BUSAT-1 was chosen based on the characteristics of software development in lab and analysis of software development model.The software overall frame structure was designed,and the mission modules and task priority was divided based on software function demand and the data flow analysis.A completed satellite communication protocols was developed,and programmed instruction of payload was parsed.Completed detailed design and code writing of telemetry,telecontrol,data management,payload management,multitasking management and security management.In order to improve the reliability of on board software,three mode redundant fault-tolerant design was used on some of the key variables,on chip watchdog was enabled and external watchdog was used to prevent the program from program runaway.Finally,related tests and modification of the software were taken,and present a simplified magnetometer calibration method in ground environment.The test results showed that the software design meet the requirements,and can operate stably in the ground simulation environment.