[Baiwen smart home] first day of the course_ Learn Embedded and understand the development mode of bare metal and RTOS

I taught myself during the holiday , This blog is to record the learning process and some experiences . So there may be some mistakes in the content , Welcome to correct .

One 、 Understand the basic route and direction of embedded learning

By watching the video of Baiwen , I learned the development direction of embedded , Know the space and salary level of relevant work , There is also a reference route for learning .

The difficulty of bare metal direction is low , There are many posts , General treatment ;RTOS The difficulty is going up , The procedure is complex and requires many , There are many posts , Pay high ;linux The driver is a little lower , Need a certain knowledge reserve , Know how to transplant and write drivers , understand linux Driving framework and some mechanisms , Most of the posts are distributed in first tier cities , The treatment is also relatively high ;linux Application is to write business logic and some small programs , There are many posts , Good treatment ;DSP and FPGA Usually as a supplementary project to learn , It's hard , This skill is required only when there are special project requirements .

Two 、ARM Architecture introduction

Most of the mainstream chip architectures I know now are ARM,A Tie you MMU function , Suitable for running advanced operating system , Realize multi task and multi process , for example Windows、MacOS、Linux、Android;R It is suitable for high performance , High real-time applications ;M It is suitable for products with low power consumption and low cost , No MMU function , Can run FreeRTOS、VxWorks、ucLinux、uc/OS.

MPU and MCU The difference is that the application scenarios are different ,MPU The performance of operation and processing is strong ,MCU The function of is relatively single , It is mainly used to control and manage other equipment .

Besides, there are DSP and FPGA Chip ,DSP Chips are used in digital signal processing , Strong computational power ;FPGA Programmable hardware , It can be used to compile common hardware circuits .

3、 ... and 、 Development process

It mainly describes the process of program compilation .

Four 、RTOS The introduction of

The development mode of bare metal machine is generally divided into polling mode and event driven mode . Polling mode is to execute functions in sequence , In this way, the execution time between functions will be affected ; The event driven method uses the corresponding time to trigger the function execution , Common interruptions , Set the global variable as the event flag bit . No multitasking 、 The concept of thread . In the case of multiple functions , The real-time performance of bare metal programs is not high .
Introduce the concept of task into the operating system , Each task can be written as an endless loop , The operating system schedules tasks according to their priority , send CPU Perform each task in time , As long as the scheduling method is good , Each task looks like parallel execution , Improved CPU Utilization ratio .