What is the difference between ARM, FPGA and DSP?

DSP (digital singnal processor) is a unique microprocessor with its own complete instruction system. It is a device that processes a large amount of information with digital signals. A digital signal processor includes a control unit, arithmetic unit, various registers, and a certain number of storage units in a small chip. It can also connect several memories on its periphery and communicate with a certain number of external devices. It has comprehensive software and hardware functions and is a microcomputer itself. DSP adopts Harvard design, that is, the data bus and address bus are separated, so that the program and data are stored in two separate spaces, allowing the instruction fetching and execution to overlap completely. That is to say, the next instruction can be fetched and decoded while executing the previous instruction, which greatly improves the speed of the microprocessor. In addition, it allows transmission between program space and data space because it increases the flexibility of the device. Its working principle is to receive analog signals, convert them into digital signals of 0 or 1, and then modify, delete, and strengthen the digital signals, and interpret the digital data back to analog data or actual environment format in other system chips. It is not only programmable, but also has a real-time running speed of tens of millions of complex instruction programs per second, far exceeding general-purpose microprocessors. It is an increasingly important computer chip in the digital electronic world. Its powerful data processing capabilities and high running speed are the two most commendable features. Because of its strong computing power, fast speed, small size, and high flexibility in software programming, it provides an effective way to engage in various complex applications. According to the requirements of digital signal processing, DSP chips generally have the following main features:

(1) One multiplication and one addition can be completed in one instruction cycle.
(2) The program and data spaces are separated, and instructions and data can be accessed simultaneously.
(3) The chip has fast RAM, which can usually be accessed simultaneously in two blocks through independent data buses.
(4) It has hardware support for low-overhead or no-overhead loops and jumps.
(5) It has fast interrupt processing and hardware I/O support.
(6) It has multiple hardware address generators that operate in a single cycle.
(7) It can perform multiple operations in parallel.
(8) It supports pipeline operation, so that operations such as instruction fetch, decoding, and execution can be performed in an overlapping manner.

Of course, compared with general-purpose microprocessors, other general functions of DSP chips are relatively weaker.

ARM (Advanced RISC Machines) is a well-known company in the microprocessor industry. It has designed a large number of high-performance, low-cost, low-energy RISC processors, related technologies and software. The ARM architecture is the first RISC microprocessor designed for the low-budget market. It is basically the industry standard for 32-bit microcontrollers. It provides a series of cores, system extensions, microprocessors and system chip solutions. The four functional modules can be configured and produced by manufacturers according to the requirements of different users. Since all products use a common software system, the same software can run in all products. At present, ARM has a market share of more than 90% in handheld devices, which can effectively shorten the time for application development and testing, and also reduce R&D costs.

FPGA is the abbreviation of Field Programmable Gate Array. It is a product further developed on the basis of programmable devices such as PAL, GAL, PLD, and is the most integrated type in application-specific integrated circuits (ASICs). FPGA adopts a new concept of logic cell array LCA (Logic Cell Array), which includes three parts: configurable logic module CLB (Configurable Logic Block), input and output module IOB (Input Output Block) and internal wiring (Interconnect). Users can reconfigure the logic module and I/O module inside the FPGA to implement the user's logic. It also has the characteristics of static reprogrammable and dynamic in-system reconstruction, so that the function of the hardware can be modified through programming like software. As a semi-custom circuit in the field of application-specific integrated circuits (ASICs), FPGA not only solves the shortcomings of customized circuits, but also overcomes the shortcomings of the limited number of gate circuits of the original programmable devices. It is no exaggeration to say that FPGA can complete the functions of any digital device, from high-performance CPUs to simple 74 circuits, which can be realized by FPGA. FPGA is like a blank sheet of paper or a pile of building blocks. Engineers can freely design a digital system through traditional schematic input method or hardware description language. Through software simulation, we can verify the correctness of the design in advance. After the PCB is completed, you can also use the online modification capability of FPGA to modify the design at any time without changing the hardware circuit. Using FPGA to develop digital circuits can greatly shorten the design time, reduce the PCB area, and improve the reliability of the system. FPGA is set by the program stored in the on-chip RAM to set its working state, so the on-chip RAM needs to be programmed when working. Users can use different programming methods according to different configuration modes. When powered on, the FPGA chip reads the data in the EPROM into the on-chip programming RAM. After the configuration is completed, the FPGA enters the working state. After power failure, the FPGA returns to a blank chip, and the internal logical relationship disappears. Therefore, the FPGA can be used repeatedly. FPGA programming does not require a dedicated FPGA programmer, only a general EPROM or PROM programmer is required. When the FPGA function needs to be modified, just replace an EPROM. In this way, the same FPGA, different programming data, can produce different circuit functions. Therefore, the use of FPGA is very flexible. It can be said that FPGA chips are one of the best choices for small-batch systems to improve system integration and reliability. Currently, there are many varieties of FPGAs, including XILINX's XC series, TI's TPC series, and ALTERA's FIEX series.

What is the difference between them? DSP is mainly used for calculation, such as encryption and decryption, modulation and demodulation, etc. Its advantages are powerful data processing capabilities and high operating speed. ARM has relatively strong transaction management functions and can be used to run interfaces and applications. Its advantages are mainly reflected in the control aspect. FPGA can be programmed with VHDL or VerilogHDL, and has strong flexibility. Since it can be programmed, debugged, reprogrammed and repeated, it can be fully designed, developed and verified. When there are small changes to the circuit, the advantages of FPGA can be more evident. Its on-site programming ability can extend the life of the product in the market, and this ability can be used for system upgrades or debugging.