First of all, from the perspective of definition and integration, the SOC chip, that is, "System on A Chip", is a programmable chip that integrates multiple functions. By integrating a variety of functional modules and peripheral interfaces on a chip to achieve communication , Calculate and control various functions. This highly integrated design allows SOC chips to support complex applications, such as smartphones, tablets, smart TVs, etc.
The MCU chip, the microcontroller unit, is a miniature computer chip that integrates the central processor (CPU), memory and various input and output interfaces. Although it also has a certain degree of integration, it mainly integrates more basic peripheral controllers, such as clocks, timers, A/D converters, UART, SPI, I2C, etc., which need to be through external memory, device and other other IC components to achieve more complex functions.
Secondly, from the perspective of power consumption and cost, the SOC chip usually uses advanced process technology and power management technology to reduce power consumption and extend the battery life. The MCU chip pays more attention to low power design to meet the application scenarios that require strict power consumption. In terms of cost, MCU chips are usually cheaper than SOC chips. This is mainly because the function of the MCU chip is relatively simple and low.
MCU classification
The MCU is divided according to the digits (data bus width), which can be divided into 4, 8, 16, 32, and 64 -bit, etc. The mainstream of the market is 8 -bit and 32 -bit;
(1) 8 -bit MCU: It has the advantages of low power consumption, low cost, convenient use and other advantages. Application scenario: industrial and commercial.
(2) 16 -bit MCU: less than 32 -bit, cost performance is not as good as 8 -bit MCU, and market share is marginalized.
(3) 32 -bit MCU: Strong computing power, the price is close to 8 -bit MCU, which can meet most complex embedded scenarios.
From the memory structure, the MCU can be divided into vonormann and Harvard structure. The vonorman structure merged the program instruction memory and data memory together. Harvard structures store the program instructions and data separately and read separately. Therefore, the program instructions and data instructions can have different data widths, usually with high execution efficiency.
Divided according to the application field, it can be divided into universal and dedicated types. General MCU refers to the basic composition of MCU, but all of the resources (including RAM, ROM, string interface, etc.) available in MCU are all provided to users, not for some special purpose. The dedicated MCU refers to the MCU specially designed according to the specific purpose. Adhering to the form of "MCU+specific components", it is usually integrated in the MCU with specific functions, such as digital signal processing units and Bluetooth protocol stacks.
Where can I read the code after the MCU initially started?
The CPU is designed to read the code at the location of the decoration address 0x00000000. First, the two words will be read continuously, namely the land of the stack pointer and the land of the removal abnormal processing function; and then jump to perform the reset abnormal processing function.
Of course, in some early ARM processor design, such as ARM7TDMI, the code at the address at the address will be executed directly after reset. The software initializes the stack pointer, and the 0 address is stored in the interrupt processing function, not the function address.
Therefore, we can have a reason to speculate that the first word is that the stack address is because the next reset and interrupt processing function involves function jump, and the content may already be stored in the stack.
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