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What Is STM32?

With the development of technology, single-chip development tools are more and more advanced, and prices are declining. When the FLASH-type microcontroller is wide. After the application of software, it is an economical and practical experimental method to use software simulation. In recent years, many single-chip has a ISP function, as long as a download line can be programmed, no longer need programmers. SST series SST series of single-chip company is integrated simulation function, with Keil software, allows users of the target board straight Then has a simulation function, the microcontroller's ease of use to a new height.

SCM development in addition to the necessary hardware, the same can not be separated from the software, Keil software is currently the most popular development MCS-51 series of single-chip software, which in recent years STM32 core Cortex-M3 processor is a standardized micro-controller structure, want to think about what is standardized? In short, Cortex-M3 processor has 32-bit CPU , Parallel bus structure, nested interrupt vector control unit, debug system, and standard storage mapping.

Nested Vector Interrupt Controller (NVIC) is a relatively critical component of the Cortex-M3 processor, which provides a standard interrupt architecture and excellent interrupt response capability for Cortex-M3-based microcontrollers , Provides a dedicated interrupt entry for more than 240 interrupt sources, and can give each interrupt source a separate priority. With NVIC, you can achieve an extremely fast interrupt response speed, only 12 cycles from receiving an interrupt request to executing the interrupt command. This very fast response speed on the one hand thanks to the Cortex-M3 kernel stack automatic processing mechanism, this mechanism is through the internal micro-code in the CPU to achieve. On the other hand, NVIC uses a technique called "tail chain" in the event that an interrupt request occurs consecutively so that successive interrupts can be serviced in six clock cycles. In the interruption of the stack stage, higher priority interrupt can be without any additional CPU cycle can be completed embedded low priority interrupt action. The details of the details I will continue to summarize. Users can set the CPU automatically into the low power state, and use the interrupt to wake up, CPU interrupt time before it will remain sleep state. You can buy it easily, as you can buy it on electronic parts online shop.

The CPU of the Cortex-M3 supports two modes of operation: the Thread Mode and the Handler Mode. Also, note that both modes have separate stacks. This design allows developers to carry out more sophisticated programming, real-time operating system support is even better. The Cortex-M3 processor also includes a 24-bit auto-reload timer that provides a periodic interrupt for the core (RTOS). In the instruction set, ARM7 and ARM9 have two instruction sets (32-bit instruction set and 16-bit instruction set), while the Cortex-M3 series processors support the Thumb-2 instruction set. Since the Thumb-2 instruction set incorporates the Thumb instruction set and the ARM instruction set, the performance of the 32-bit instruction set and the code density of the 16-bit instruction set are balanced. Moreover, ARM Thumb-2 specifically for the C / C + + compiler design, which means that the Cortex-M3 series of processor development and application can be completed in the C language environment.

The introduction of the STM32 microcontroller marks a significant step in ST's main line (low-cost main line and high-performance main line). STM32 was originally released with 14 different models, divided into two versions: the highest CPU clock is 72MHZ "enhanced" and the highest CPU clock is 36MHZ "basic". These different STM32 models built-in Flash maximum reach 128KB, SRAM up to 20KB, at the beginning of the STM32 release, configuration larger Flash, RAM and more complex peripherals version has been in the planning of the. No matter what version, what type of STM32 devices, they are compatible with pin functions and application software. This allows the developer to use the STM32 family of microcontrollers without having to change the PCB to replace the device as needed.

Reference: how to program atmega328p

how to connect 74hc595 to arduino