1 is a pulse width modulation (PWM): to perform a method of controlling a very effective technology for the analog output of the digital microprocessor circuits, widely used in many fields from the measurement, control and communication to the power transformed. Usually a DC motor speed.
2. External interrupts: external interrupts the microcontroller is an internal mechanism to deal with external events in real time. When some external event occurs, the microcontroller interrupt system will force the CPU to suspend the program being executed and instead go for processing interrupt events; after processing the interrupt. And return to the program at the interrupted, continue execution.
3. The serial communication (USART): Serial bitwise (bit) communication system for transmitting and receiving byte.
4. The system clock tick (the SysTick): task reference in a single procedure since it determines the serial architecture of its tasks, which raises the question: When a task problems will follow implicated mission, which led to the collapse of the entire system. To solve this problem, you can use real-time operating system (RTOS). Because RTOS architectures in parallel processing tasks, the collapse of a single task and do not implicate the entire system. So users for reliability to design their own applications might Based on RTOS. Meaning SYSTICK existence is necessary to beat the clock, providing a rhythmic "heartbeat" as an RTOS task scheduling.
Timer resources of the microcontroller is generally more abundant, such as the presence of 8 STM32 timer, then why should a SYSTICK? The reason is that all ARM Cortex_M3 kernel based controllers with SysTick timer, so to facilitate the transplant procedure between different devices. The use of RTOS first job often is to migrate to a hardware platform developers, due to the presence SYSTICK undoubtedly reduces the difficulty of transplantation.
SysTick timer operating system services in addition to outside, can also be used for other purposes: for example, as an alarm, for measuring time and the like. Note that when the processor during commissioning are ordered a halt (halt), the SysTick timer will also be suspended operations.
5. watchdog: In order to prevent runaway system, enhance the stability of the system, the STM32 built two watchdog, window watchdog and independent watchdog. Independent watchdog outside the main program is independent, driven by a dedicated low-speed clock can work completely independently. Window watchdog is configurable through a window of time to work with independence is not strong, but more precise than the independent watchdog.
6. The backup register (BKP): a set of registers for storing a set of user application data. In the backup domain, when Vdd supply is cut off, they still maintain powered by Vbat. When the system is in standby mode wakes up, or system reset or power reset, they will not be reset.
7. Real-time clock (RTC): The RTC is an independent timer. RTC module has a set of successive counts of the counter, in the corresponding software configuration, may provide a clock calendar function. Modify the value of the counter is re-set the current time and date.
8. Nested Vectored Interrupt Controller (NVIC): interrupt packet is used to assign priority and preemption priority response; 8 bits for setting a priority interrupt sources. Preemption priority: higher pre-emption priority interrupt can interrupt preempt lower priority interrupts. This is achieved interrupt nesting foundation. NVIC presence not only facilitate low-latency exception and interrupt handling, but also to achieve the registers and power management systems.
9. The analog to digital converter (ADC): in the form of a continuous analog signal into digital form discrete signals. Real world analog signals, such as temperature, pressure, sound, image or the like, needs to be converted more easily stored, processed and transmitted in digital form.
10. The digital to analog converter (DAC): digital / analog conversion module is a 12-bit digital input, digital output voltage / analog converter?. Also it provides many other features, such as: noise generation, triangle wave generation.
11.DMA controller: to provide high-speed data transfer between peripherals and memory or between a memory and a memory. DMA transfer to copy data from one address space to another address space. When the hardware memory with high speed data transfer between a peripheral control circuit, a dedicated processor to achieve direct data transfer, it must be able to replace the function of the program control by the CPU and transfer the completed software
12.I2C bus: transmitting the received data and combined data, using only two buses to complete the communication: a clock line, data line. The difference is that the serial port, the serial data line is unidirectional, and the I2C data line is bidirectional.
13.SPI bus (Serial Peripheral Interface): is a high-speed, full-duplex, synchronous communication bus, and occupies only four wires on the pins of the chip, saving chip pins, as well as PCB savings in layout space, to provide convenient, it is for this simple-to-use features, more and more chip integrates this communication protocol.
14.I2S bus: also known as integrated circuit built-in audio bus is a bus standard Philips audio data transmission between digital audio devices and the development of the dedicated bus for data transfer between the audio equipment is widely used multimedia systems. It uses a separate design wires along the transmission clock of the data signal, by separating the data and clock signals, to avoid the distortion induced by the difference, the cost savings for the user to buy specialized equipment to resist the audio jitter.
15.CAN bus: CAN bus widely used in automobiles, ships electronic communications device in fact is also widely used CAN, as the country's increasing emphasis on coastal defense, the demand for the CAN will be growing. No clock signal for data transmission by a differential signal.
16.SDIO Interface: SD is the extension type interface, which can be connected in addition to the SD card, the support equipment can also be connected SDIO interface such as the SDIO WiFi module, so that an extended wireless LAN device communication function.
17.Flash memory: the internal STM32 Flash divided into two parts, a main storage and fast information quickly. Fast information is divided into a system memory byte select line and the two parts. Fast main storage for storing programs, finished, compiler, download, usually stored here, a system memory for storing the boot program.
18. The flight control system: a stable flight attitude, flight control chess autonomous or semi-autonomous flight control system is the brain of the aircraft. Mainly by a gyroscope, an accelerometer, a geomagnetic sensor, air pressure sensor, an ultrasonic sensor, a light flow sensor, GPS module and a control circuit.
19. The high and low: in the digital logic circuit, a low level indicates 0, 1 represents a high level. Predetermined low level is generally 0 ~ 0.25V, a high level of 3.5 ~ 5V.
20.CPU Category: CPU into a MCU (micro-controller, microcontroller, or called) and an MPU (Micro) categories, their essential difference is the MMU (memory management unit), which is support for virtual memory space. Raspberry Pi and S3C2440 MPU belongs to the class, while the Arduino and STM32 MCU belongs to the class. They have a huge gap in computing power.