MCU features:
(1) by limiting the degree of integration, on-chip memory capacity is small, the general ROM: 8KB or less;
the (2) RAM: 256KB or less.
(3) high reliability
(4) easy expansion
(5) strong control function
(6) is easy to develop
the characteristics of ARM:
(1) inexpensive own program memory (FLASH) and non-volatile data memory (EEPROM). The memory can be electrically erased many times, the test program development easier, more reliable.
(2) high speed, low power consumption. In the same external oscillator and microcontroller M51 conditions, the operating speed of the AVR microcontroller M51 is 30-40 times; and increased sleep function and CMOS technology, so that power consumption is much lower than M51 microcontroller.
(3) industrial products. With a high current output can directly drive ××× and relays, watchdog timer, to prevent the program to go fly, resulting in improved anti-jamming capability of the product.
(4) Super RISC function, with 32 general-purpose working registers, the microcontroller 32 corresponds to the M51 accumulator! Thereby overcoming the bottleneck single accumulator work.
(5) easy to download. AVR microcontroller can be downloaded to a parallel serial download, without expensive programmer. In addition, you can also download online! That program can be modified directly on the circuit board and burning.
(6) having an analog comparator, pulse width modulators, analog to digital conversion. The analog signal processing of the industrial control more simple and convenient.
Function key resources within the microcontroller (7) parallel port, timer counter, interrupt system has been greatly improved, making it more suitable for real-time control of industrial processes.
(8) an external clock frequency can also be used inside the microcontroller's own oscillator frequency can be set within the 1MHz-8MHz, the development of such production more simple hardware.
(9) a powerful communication, built-in synchronous serial interface SPI, universal serial bus UAST, two-wire serial bus interface TWI (I2C), so that the control network, the data transfer is more convenient.
(10) Super privacy function, the application may employ multiple protection lock function. Low-cost manufacturers can quickly complete product commercialization, and so on. In addition to these features important feature of the "zero peripherals" is also embedded AVR microcontroller. Since the chip has a built-in program memory, crystal and adds inline assembler function.
Therefore AVR microcontroller chip connected to the DC power source, downloading programs can work independently. No additional external devices, without using an expensive programming and simulation apparatus. This gives us learning and development has brought convenience.
FPGA features:
(1) using the FPGA design ASIC circuit (ASIC), a user need not cast film production, can be obtained in combination of the chip.
(2) FPGA to do the test specimen other semi-custom or full-custom ASIC circuit.
Internal (3) FPGA rich trigger and I / O pins.
(4) FPGA circuit, ASIC design cycle is the shortest, lowest development costs, one of the smallest risk devices.
(5) FPGA CMOS technology high speed, low power, compatible with CMOS, TTL level.
It can be said, FPGA chip is a low-volume system to improve system integration, reliability of one of the best choice.
FPGA which is set by the operating state stored in the program RAM chip, therefore, necessary to program the chip RAM work. The user can configure different modes, different ways of programming.
When powered, FPGA chip to read the data into the EPROM chip program RAM, the configuration is complete, FPGA into operation. After the power failure, FPGA restored to a white sheet, the internal logic disappears, therefore, FPGA can be used repeatedly. FPGA programming FPGA without dedicated programmer, only a common EPROM, PROM programmer can be used. When the need to modify the FPGA, you simply need to change an EPROM. Thus, the FPGA with one, different programming data, may produce different circuit functions. Therefore, FPGA is very flexible to use.
Characteristics of embedded systems:
1, the system kernel small
because embedded systems are typically used in small electronic devices, the system resources are relatively limited, compared with the traditional operating system kernel is much smaller. For example, Enea's OSE distributed system, the kernel only 5K, and the Windows kernel? Simply not comparable.
2, specific and strong
embedded systems highly personalized, which is a combination of software and hardware systems are very close, generally the transplant system for the hardware, even within the same brand, same range of products also need to system hardware variations and changes in ongoing changes. At the same time for different tasks, often require significant changes to the system, compiler and downloaded to the system by combining the "upgrade" such modifications and general software is completely two concepts.
3, the system streamline
embedded systems generally do not have system software and application software are clearly differentiated, functional design and does not require too complicated the realization, so that one system will help control costs, but also conducive to system security.
4, high real-time system software (OS) is the basic requirement of embedded software. And the software requirements of solid state storage, to increase speed; software code requires high quality and reliability.
5, embedded software development in order to move towards standardization, it is necessary to use multi-tasking operating system
for embedded systems applications can not run the operating system directly on the chip; but for a reasonable schedule multiple tasks, use of system resources, system functions, and and experts library function interface, the user must own matching RTOS (Real-time Operating System) development platform, so as to ensure real-time program execution, reliability, and reduce development time to ensure software quality.
6. Embedded systems development tools and environment need to be developed.
Due to bootstrap itself does not have the ability to develop, even if the user does not usually function in which the program to be modified after the design is complete, it is necessary to develop a set of development tools and environment to these tools and the environment in general is based on a general-purpose computer software and a variety of hardware logic analyzers and mixed signal oscilloscopes. Often the concept of host and target the development, the development of a program for the host, as a final target execution machine, when the developer needs to be combined alternately.