Now that we are ready to develop STM32 and the software and hardware are ready, let's understand what STM32 is.
STM32 is the name of a series of 32-bit chips designed by ST (ST), subdivided into three series: L, F, and H.
The F series is the most classic series. The basic chip of the F series is the F1 series, and the price is low. Although the sparrow is small and full of organs, my favorite system for course design is the smallest system board of STM32F103C8T6 supplemented by a hole board. Easy. High-performance F4, F7 series;
The H series is a high-performance MCU series, the main frequency can reach 200MHz, and the latest H7 is still multi-core heterogeneous, which means that one core can be used for control, and the other core is specially used for image and other algorithm processing;
The L series is a low power consumption series, and their shadows are commonly seen in IoT devices.
The difference between STM32 and 51. First of all, in terms of the number of bits, STM32 is a 32-bit chip, the addressing space is 32 bits, the register length is 32 bits, and the 51 single-chip has only a poor 8 bits. The advantage of high digits is that 32 can have larger ROM and FLASH, and the ability to process data is stronger. From the instruction set point of view, the 32-run ARM reduced instruction set runs faster than the traditional 51 instruction set. The traditional 51 instruction set 1 machine cycle requires 12 clock cycles or 24 clock cycles, while the 32 instruction set one machine cycle is often within 1 clock cycle (the data in the Datasheet is 1M clock, the average instruction executed is 1.25M, because the clock cycles occupied by different instructions are also different, for example, displacement instructions are faster than multiply and divide instructions). Of course, there are currently advanced 51 instruction sets. For example, the instructions of the CIP51 core used in the C8051 series are often between 1 and 2 clock cycles, and only 4 instructions are greater than 4 clock cycles. From this point of view, the operating efficiency of STM32 is far higher than that of the traditional 51 single chip microcomputer. Usually STM32 supports dozens of megabits of main frequency (64M, 72M, etc.) while the traditional 51 single chip microcomputer does not support such a high frequency. That is to say, the advantages of STM32 are better than that of 51 single-chip microcomputer.
Here uses an internal structure diagram of STM32F103 to show the structure of STM32:
Usually when reading the chip manual, first reading the internal structure section helps to quickly understand the working principle of this chip, chip peripherals and so on. It can be seen from this picture that STM32 has many external interfaces, including GPIO, UART, IIC, SPI, ADC, DAC, etc. The internal peripheral bus of STM32 is AHB-> APB1 and APB2. GPIO, TIM1, TIM8 and other peripherals are hung on APB1. Peripherals such as TIM2, TIM3, USART2, UART4 are hung on APB2. Here is a general idea, you don't need to write it down completely, you can find the corresponding bus through this picture when using the corresponding peripherals.
The clock tree inside STM32 is as follows:
The clock is the heart of the single chip microcomputer. All instructions and peripherals work according to the clock. If the clock is broken, no beautiful code will work. Therefore, it is necessary to master the clock tree of STM32. Here is the same as the internal structure. In this chapter, we only do understanding, and do not need to master it completely. You can gradually master the clock tree in the process of using peripherals.
Seeing this, you may have a general understanding of STM32, maybe you don't understand anything, but it doesn't matter. This chapter does not need to watch the series, skip the next chapter is no problem.