First of all, "embedded" is a concept, an accurate definition is not, and each book has its own definition. However, the main idea is the same, that is, compared to a general-purpose system such as a PC, the embedded system is a dedicated system, and its structure is streamlined. Only hardware and software are required to retain the necessary parts, and unnecessary parts are cut off. Therefore, embedded systems generally have features such as portability, low power consumption, and single performance. Then, MCUs, DSPs, and FPGAs belong to the category of embedded systems and are tools used to achieve a certain purpose. MCU commonly known as "microcontroller" after so many years of development, has long been not only 51 Princeton structure, performance has also been greatly improved. Because MCUs must execute programs sequentially, they are suitable for control and are used in many industries. The ARM is a company that specializes in designing MCUs. Due to its advanced technology and proper strategy, the market share of the microcontrollers is huge in these two years. There are many types of ARM microcontrollers, from low-end M0 (small appliances) to high-end A8, A9 (mobile phones, tablet computers) are very popular, so it is not ARM microcontroller must be on the system, the key to see the application. The DSP is called a digital signal processor. Its structure is different from that of the MCU, which speeds up the operation and highlights the computing power. Think of it as a super fast MCU. Low-end DSPs, such as the C2000 series, are mainly used for motor control, but TI seems to call it a DSC (digital signal controller) between the MCU and the DSP. High-end DSPs, such as the C5000/C6000 series, are generally used for video image processing and communications equipment where large amounts of computation are required. The FPGA is called a field-programmable logic array. It has nothing in it. It's like a blank page. It needs to be designed by a programmer. What all its functions are hardware, including VHDL and Verilog HDL programming is also a hardware category. It is generally referred to as "logic". If you are NB, you can turn it into an MCU or a DSP. Because the internal structure of the MCU and the DSP are all well-designed, they can only be processed sequentially through software programming, while the FPGA can be processed in parallel and sequentially, so it is the fastest in comparison. So why do MCUs, DSPs, and FPGAs exist at the same time? That is because the internal structure of the MCU and the DSP is carefully designed by the IC designer. When the same function is completed, the power consumption and price are much lower than that of the FPGA. Moreover, the development of the FPGA itself is more complicated, and more manpower and financial resources are needed to complete the same function. Therefore, each one has its own strengths and each has its own place. However, there has been a convergence between the three currently, ARM's M4 series added a streamlined DSP core, TI's DaVinci series itself is ARM + DSP structure, ALTERA and XINNLIX new FPGAs include ARM's Nucleus inside. So the relationship between the three is more and more like the three circles of the three primary colors. In a word, "you have me, I have you." Where do hardware engineers learn to start? SCM: Usually no operating system for simple control, such as elevators, air conditioners and so on. Dsp: used for complex calculations such as discrete cosine transform, fast Fourier transform, commonly used in image processing, used in digital cameras and other equipment. Arm: A British chip design company, but does not produce chips. Only sell intellectual property. Fpga: Field Programmable Gate Array. The circuit design completed with hardware description language (Verilog or VHDL) can be quickly integrated into FPGAs for testing. It is the mainstream of modern IC design verification technology. Embedded is relative to desktop computers, the system can be tailored, different shapes, may be volume, power consumption, cost constraints, real-time requirements, such as oscilloscopes, mobile phones, tablet computers, fully automatic washing machines, routers, digital cameras, Although these devices do not see the existence of a desktop, they all have one or more embedded systems at work. According to the functional complexity of the object system and the computational processing complexity, different options are provided. For a simple home appliance control embedded system, using a simple 8-bit microcontroller is sufficient, cheap, for mobile phones and game consoles, you must use 32-bit ARM and DSP chips. FPGA is a more hardware-oriented implementation. So to become a hardware engineer through learning, start with a microcontroller and learn ARM and DSP. Seven mainstream microcontrollers on the market The single-chip microcomputer can be described as overwhelming and varied in variety. The developers are overwhelmed and the development is quite rapid. From the 80s of the last century, from the 4-8 bits at the time to the current high-speed single-chip microcomputers. Each manufacturer also has speed, memory, and functionality. The unevenness has also emerged among a large number of manufacturers with representative MCUs: Atmel, TI, ST, MicroChip, ARM... The domestic macro-chip STC microcontroller is also available in circles. point… Here are the advantages and disadvantages of the 51, MSP430, TMS, STM32, PIC, AVR, and STC microcontrollers. The most widely used 8-bit MCU is certainly the easiest microcontroller for beginners to learn. It was first introduced by Intel. Due to its typical structure and perfect bus-specific register centralized management, numerous logic bit operation functions and rich control-oriented The instruction system, which can be called a generation of "classic", laid the foundation for the development of other SCMs in the future. The 51-chip microcomputer has become a classic, has become the easy to use microcontroller has the following characteristics: characteristic: 1. From internal hardware to software, there is a complete bit-oriented operating system, called a bit processor, where the processing object is not a word or byte but a bit. It can not only process certain bits of certain special function registers on the chip, such as transfer, set, clear, test, etc., but also perform bit logic operation. Its function is very complete and it is easy to use. 2. At the same time, a dual-function address range has been specially opened in the on-chip RAM section, which is extremely flexible. This function undoubtedly provides users with great convenience. 3. Multiplication and division instructions, which also bring convenience to programming. Many 8-bit microcontrollers do not have multiplication functions, and they have to be programmed with a subroutine call for multiplication. This is very inconvenient. Disadvantages: (although it is classic but the shortcomings are still very obvious) 1. AD, EEPROM and other functions need to expand, increase the burden on hardware and software 2. Although the I/O pin is easy to use, it has no output capability at high level. This is also the biggest weakness of the 51 series microcontrollers. 3. The operation speed is too slow, especially the double data pointer. If it can be improved, it can bring great convenience to programming. 4. 51 Poor protection ability, it is easy to burn chips Application range: Currently used in a large number of teaching occasions and occasions where performance requirements are not high Most Used Devices: 8051, 80C51MSP430 Microcontrollers MSP430 series MCU is a 16-bit ultra-low power mixed-signal processor that Texas Instruments introduced to the market in 1996. The biggest bright spot left by people is low power consumption and high speed. Assembly language is very flexible. There are many addressing modes, few instructions, and easy to use. Mainly due to its practical needs, many analog circuits, digital circuits and microprocessors are integrated on one chip to provide "single-chip" solutions. Its rapid development and continuous expansion of its application mainly depend on the following characteristics... characteristic: 1. Powerful processing capabilities, using a reduced instruction set (RISC) architecture, rich addressing modes (seven source operand addressing, four destination operand addressing), compact 27-kernel instructions, and a large number of Analog instructions; a large number of registers and on-chip data memory can participate in a variety of operations; there are efficient table look-up processing instructions; a high processing speed, and an instruction cycle of 125 ns in an 8-MHz crystal drive. These features ensure that an efficient source program can be produced 2. In the aspect of computing speed, it can realize 125ns instruction cycle under the drive of 8MHz crystal. 16-bit data width, 125ns instruction cycle, and versatile hardware multiplier (can achieve multiplication and addition), can realize some algorithms for digital signal processing (such as FFT, etc.) 3. In terms of ultra-low power consumption, the reason why the MSP430 microcontroller has ultra-low power consumption is because it has its unique features in reducing the power supply voltage of the chip and the flexible and controllable operating clock. The supply voltage is 1.8~3.6V. Therefore, when operating under a 1MHz clock condition, the current of the chip will be around 200~400uA, and the minimum power consumption of the clock shutdown mode is only 0.1uA. Disadvantages: 1. Personal feeling is not easy to use, is not suitable for beginners to get started, the information is relatively small, can only go to the official website to find 2. account for the instruction space is larger, because it is 16-bit microcontroller, the program word unit, and some The instruction actually occupies 6 bytes. Although the program is simple on the surface, it takes up a lot of space compared to the pic microcontroller. Applications: Most widely used devices in low-power and ultra-low power industrial applications: MSP430F series, MSP430G2 series, MSP430L09 series TMS microcontrollers Here also mentioned TMS series MCU, although not mainstream. The 8-bit CMOS microcontroller introduced by TI has a variety of memory modes and a variety of peripheral interface modes, which are suitable for complex real-time control applications. Although not as good as the STM32 and not as impressive as the MSP430, the TMS370C series microcontrollers provide real-time system control with cost-effective integration by integrating advanced peripheral function modules and various chip memory configurations. At the same time using high-performance silicon gate CMOS EPROM and EEPROM technology. Low operating power CMOS technology, wide operating temperature range, noise suppression, plus high performance and rich on-chip peripheral functions, make TMS370C series microcontrollers have applications in automotive electronics, industrial motor control, computers, communications and consumer applications . STM32 microcontroller The STMicroelectronics STM32 series microcontrollers introduced by ST manufacturers, the industry's friends all know that this is a series of high-performance microcontrollers, should not have one, the function and its powerful. It is based on the ARM Cortex-M core specifically designed for embedded applications that require high performance, low cost, and low power consumption, while also providing best-in-class peripherals: The 1μs dual 12-bit ADC, 4 Mbit/s UART, 18 Mbit/s SPI, and so on, also have good performance in terms of power consumption and integration, and is, of course, slightly inferior to the MSP430's power consumption. Some, but this does not affect the degree of enthusiasm of engineers for it, due to its simple structure and easy-to-use tools coupled with its powerful features in the industry famous ... Its powerful features are mainly reflected in: Features: 1. Core: ARM 32-bit Cortex-M3 CPU, maximum operating frequency 72MHz, 1.25DMIPS/MHz, single-cycle multiplication and hardware division 2. Memory: On-chip 32-512KB flash memory is integrated. 6-64KB of SRAM memory 3. Clock, reset and power management: 2.0-3.6V power supply and I/O interface drive voltage. POR, PDR, and programmable voltage detector (PVD). 4-16MHz crystal oscillator. Embedded 8MHz RC oscillator circuit calibrated before shipment. Internal 40 kHz RC oscillator circuit. PLL for the CPU clock. 32kHz crystal with calibration for RTC 4. Debug mode: serial debugging (SWD) and JTAG interface. Up to 112 Fast I/O Ports, Up to 11 Timers, Up to 13 Communication Interfaces Most Used Devices: STM32F103 Series, STM32 L1 Series, STM32W Series PIC Microcontrollers The PIC microcontroller series is a product of Microship, which is divided into three levels, namely Basic, Intermediate, and Advanced. It is one of the fastest growing microcontrollers in the market. The CPU adopts a RISC architecture with 33 and 35 respectively. The 58 instructions, which are simplistic instruction sets, use the Harvard dual-bus architecture and operate at a fast speed. They enable parallel access to program memory accesses and data memory accesses. This instruction pipeline architecture completes two parts in one cycle. One is to execute instructions and the other is to fetch the next instruction from the program memory, so that it takes only one cycle for each instruction as a whole, which is one of the reasons for high-efficiency operation. In addition, the PIC microcontroller has become a very hot single-chip microcomputer. Nothing more than the following features: Features: 1. It has the characteristics of low working voltage, low power consumption, strong driving ability and so on. The I/O ports of the PIC MCUs are bidirectional, and their output circuits are CMOS complementary push-pull output circuits. The I/O pin has added a direction register for setting the input or output status, thus resolving the same input and output status of the 51 series I/O pin when it is high. 2. When setting 1, the input state, and regardless of whether the foot is high or low, external high impedance state; set 0 when the output state, regardless of the level of the foot, are low Resistance state, there is a considerable drive capacity, low-level suction current up to 25mA, high-level output current up to 20mA. This is a great advantage compared to the 51 series. 3. It can directly drive the digital display and the external circuit is simple. Its A/D is 10 bits, which can meet the accuracy requirements. With online debugging and programming (ISP) function. Inadequacies: Its special registers (SFRs) are not concentrated in a fixed address range (80-FFH) like the 51 series, but are scattered in four address ranges. Only five special registers PCL, STATUS, FSR, PCLATH, and INTCON appear simultaneously in the four memory banks. However, in the programming process, it is necessary to deal with dedicated registers, and the corresponding memory bank must be repeatedly selected, that is, the status register STATUS. Bit 6 (RP1) and Bit 5 (RP0) are set or cleared. The data transmission and logical operation basically have to be carried out through the working register W (equivalent to the 51 series accumulator A), and the 51 series can also be transmitted directly through the registers, thus the PIC microcontroller bottleneck phenomenon than the 51 series Worse still, this friend in programming should have a deep understanding. Most Used Devices: PIC16F873, PIC16F877AVR Microcontrollers AVR microcontroller is a relatively novel one-chip computer that Atmel Company introduces, its remarkable characteristic is high performance, high speed, low power consumption. It cancels the machine cycle, uses the clock cycle as the instruction cycle, and implements the flow operation. AVR microcontroller instructions are word-based and most instructions are single-cycle instructions. A single cycle can perform the function of this instruction while completing the reading of the next instruction. Since the clock frequency is usually 4 to 8 MHz, the shortest instruction execution time is 250 to 125 ns. AVR single-chip microcomputer can become the hottest single-chip microcomputer recently, the main characteristics: Features: 1. The AVR series does not have a structure similar to that of the accumulator A. It mainly implements the function of A through the registers of R16 to R31. In the AVR, there is no data pointer DPTR like the 51 series, but is composed of three 16-bit registers X (composed of R26, R27), Y (composed of R28, R29), and Z (composed of R30, R31). The function of the data pointer (equivalent to three sets of DPTR), but also for post-increment or decrement and other operations, and in the 51 series, all logic operations must be carried out in A; and AVR can be in any two Between the registers, eliminating the back and forth in A, these are better than the 51 series. 2. The special register of AVR is concentrated in the 00~3F address range, and it is not necessary to perform the process of selecting a bank first as in the PIC, which is more convenient than PIC. AVR's on-chip RAM address range is 0-00DF (AT90S2313) and 0060-025F (AT90S8515, AT90S8535), which occupy the address of the data space, these on-chip RAM is only used to store data, usually does not have universal Register function. When the program is complicated, the general-purpose registers R0-R31 are not enough; while the 51-series general-purpose registers are as many as 128 (four times that of the AVR), this feeling does not occur when programming. 3. The AVR I/O pin is similar to the PIC. It also has a direction register for controlling the input or output. Under the output state, the high-level output current is about 10 mA, and the low-level current is 20 mA. This is not as good as the PIC, but it is still better than the 51 series... Disadvantages: 1. There is no bit operation, all control and judgment of the relevant register bit are performed in byte form. There is a big difference in writing between the 2.C language and the 51 C language, which makes it very difficult for a friend who started learning 51 SCM. 3. There are a total of 32 general-purpose registers (R0 to R31), and the first 16 registers (R0 to R15) cannot directly deal with the immediate data, so the versatility has decreased. In the 51 series, all of its general-purpose registers (addresses 00 to 7FH) can deal directly with immediate data and are obviously better than the former. Most Used Devices: ATUC64L3U, ATxmega64A1U, AT90S8515STC Microcontrollers Speaking of STC single-chip microcomputer someone will say, STC can also be regarded as the mainstream, it is estimated that should be sprayed ~ ~ we based on it is domestic relatively good one-chip computer. STC single-chip microcomputer is a single-chip clock / machine cycle microcontroller production, said STC microcontroller is a combination of 51 and AVR, it was said that AVR is 51 alternative microcontroller, but the AVR microcontroller in place control and C language is very large The difference. The STC MCU Qiaicui combines the advantages of 51 and AVR, although the function is less powerful than the AVR, but in the AVR can find the function, basically have in the STC, while the STC microcontroller is 51 core, which gives 51 microcontroller-based The engineers have provided great convenience, saving time for learning AVR while also losing the AVR's various functions... STC single-chip microcomputer is a new generation of 8051 single-chip microcomputer 51 with high speed, low power consumption and super anti-interference. The instruction code is fully compatible with the traditional 8051, but the speed is 8 to 12 times faster, and the internal reset MAX810 dedicated reset circuit. 4-way PWM 8-channel high-speed 10-bit A, D conversion, for the motor control of the motor supplier, strong interference occasions, as a new series of single-chip microcomputer after the 51 single-chip microcomputer ... characteristic: 1. Download the burning program with the serial port is easy to use, easy to use, with a large number of learning materials and video, the most famous of which belongs to Du teacher's video, a lot of friends who are interested in SCM are through this video entry, At the same time with a wide voltage: 5.5 ~ 3.8V, 2.4 ~ 3.8V, low-power design: idle mode, power-down mode (wake-up by external interrupt) 2. STC microcontroller has application programming, debugging is more convenient; with 10 bit AD, internal EEPROM, can work under 1T/machine cycle, the speed is 8 to 12 times the traditional 51 microcontroller, the price is also cheaper. 3.4 Channel capture/compare unit, STC12C2052AD series is 2 channels, can also be used to implement 4 timers or 4 external interrupts, 2 hardware 16-bit timers, compatible with 8051 timers. 4-way PCA can also realize 4 timers, with hardware watchdog, high-speed SPI communication port, full-duplex asynchronous serial port, compatible with the 8051 serial port, and also has an advanced instruction set structure, compatible with common 8051 instructions. set. PS: STC single-chip function is not as strong as AVR, STM32, and the price is not cheaper than 51 and ST32, but these are not important, it is important that this is a relatively good single-chip microcontroller, I wish domestic microcontroller can all the way Changhong ... Most Used Device: STC12C2052ADFreescale Microcontroller Mainly for S08, S12 such microcontrollers, of course, Freescale microcontroller is far from this. Freescale MCUs adopt Harvard architecture and pipeline instruction structure. They show low cost and high performance in many fields. Their architecture saves a lot of time for product development. In addition, Freescale provides a variety of integrated modules and bus interfaces, which can be used more flexibly in different systems. The unique features of Freescale MCUs are as follows: 1. Full range: From low-end to high-end, from 8-bit to 32-bit full range of the full range, its introduction of 8-bit / 32-bit pin compatible QE128, can be directly transplanted from 8-bit to 32-bit, to make up for single chip industry 8/ A missing link in the 32-bit compatibility architecture. 2. A variety of system clock modules: three modules, seven kinds of work modes. Multiple clock source input options, different MCUs have different clock generation mechanisms, which can be RC oscillators, external clocks or crystal oscillators, or internal clocks. Most CPUs have the above three modules at the same time! Can run on FEI, FEE, FBI, FBILP, FBE, FBELP, STOP these seven kinds of work patterns. 3. A variety of communication module interfaces: Freescale microcontrollers integrate almost all kinds of communication interface modules: including serial communication interface module SCI, multi-master I2C bus module, serial peripheral interface module SPI, MSCAN08 controller module, universal serial bus Module (USB/PS2) 4 has more optional modules: with LCD driver module, with a temperature sensor, with UHF transmitter module, contains a synchronous processor module, MCU with a synchronous processor also has a screen display module OSD, there are a few The MCU has a ring detection module RING and a dual tone multi-frequency/tone generator DMG module. 5. High reliability, strong anti-interference, a variety of pin counts and package options. 6. Low power consumption, perhaps Freescale series of microcontroller power consumption is not MSP430 low, but he has all static "wait" and "stop" two modes, to reduce your overall power consumption! Recently introduced several models Ultra-low power consumption is comparable to that of the MSP430! Most Used Devices: MC9S12G Series If you really want to be divided into one or two or three in these MCUs, then if you want to follow the masses, no matter what the 51 microcontroller is preferred; if you are pursuing high cost performance, STM32 will be your ideal choice; if you desire ultra-low power, MSP430 It certainly won't disappoint you; if you want to support homegrown, STC will make you excited... Nantong Boxin Electronic Technology Co., Ltd. , https://www.ntbosen.com