How to upgrade from single chip microcomputer to DSP

　　In the past few decades, the widespread application of single-chip microcomputers has realized simple intelligent control functions. With the progress of informatization and the rapid development of computer science and technology, signal processing theory and methods, the amount of data that needs to be processed is getting larger and larger, and the requirements for real-time performance and accuracy are getting higher and higher. Low-end single-chip microcomputers can no longer meet the requirements. In recent years, the performance of various integrated single-chip DSPs has been greatly improved, and software and development tools have become more and more numerous and better; the price has dropped significantly, making DSP devices and technologies easier to use, and the price can also be accepted by the majority of users; more and more single-chip microcomputer users have begun to choose DSP devices to improve product performance, and the time is ripe for DSP devices to replace high-end single-chip microcomputers.

　　This article will compare the microcontroller and DSP devices in terms of performance, price, etc. On this basis, taking TI's TMS320C2XX series DSP devices as an example, explore the feasibility of DSP devices replacing microcontrollers.

　　
Comparison between DSP devices and single-chip microcomputers
　　
1. Characteristics of single-chip microcomputers

　　The so-called single-chip microcomputer is a chip that integrates CPU, RAM, ROM (EPROM or EEPROM), clock, timer/counter, serial and parallel I/O ports with multiple functions. Such as Intel's 8031 ​​series. In addition to the above basic functions, some also integrate A/D and D/A, such as Intel's 8098 series. In summary, single-chip microcomputers have the following characteristics:

　　It has bit processing capability and emphasizes control and transaction processing functions.
It is inexpensive. For example, a low-end single-chip microcomputer costs only a few yuan.
It has a complete development environment, complete development tools, and a large amount of application materials.
It has sufficient reserve talents. Most domestic universities have opened single-chip microcomputer courses and single-chip microcomputer experiments.

2. Characteristics of DSP devices

　　Compared with single-chip microcomputers, DSP devices have a higher degree of integration. DSP has a faster CPU, larger memory, built-in baud rate generator and FIFO buffer. It provides high-speed, synchronous serial port and standard asynchronous serial port. Some chips integrate A/D and sample/hold circuits to provide PWM output. DSP devices use improved Harvard structure, with independent program and data space, allowing simultaneous access to programs and data. Built-in high-speed hardware multipliers and enhanced multi-stage pipelines give DSP devices high-speed data computing capabilities. DSP devices are 8 to 10 times faster than 16-bit single-chip microcomputers in single instruction execution time, and 16 to 30 times faster in completing a multiplication and addition operation. DSP devices also provide highly specialized instruction sets, which improve the computing speed of FFT fast Fourier transform and filters. In addition, DSP devices provide JTAG interfaces, have more advanced development methods, and are more convenient for batch production testing. Development tools can achieve full-space transparent simulation without occupying any user resources. The software is equipped with an assembler/link C compiler and a C source code debugger.

　　At present, the most widely used DSP device in China is the TMS320 series produced by Texas Instruments (TI) in the United States. The localization of DSP development systems has been completed. The price of domestic development systems is at least half of that of imported systems. Some, such as the TMS320C2XX development system, are only 1/5 of the price of imported development systems. This has greatly stimulated the application of DSP devices. At present, many universities have plans to establish DSP laboratories. TI and Beijing Wenting have formulated university support plans to promote the application and promotion of domestic DSP devices.

　　
3. Large-scale promotion of DSP devices is just around the corner

　　Through the above comparison, we can conclude that DSP device is a single-chip microcomputer with high-speed computing capability.

　　From the application perspective: DSP devices are computationally intensive, while MCUs are transaction-intensive. DSP devices can replace MCUs, but MCUs cannot replace DSP. The price of DSP devices has dropped significantly, approaching that of MCUs. DSP devices widely use JTAG hardware emulation, making hardware debugging easier than MCUs. The localized DSP development system provides the possibility for more users to adopt DSP devices. The market conditions for the technology and price of DSP to replace MCUs are mature, and large-scale promotion is just around the corner.

　　Typical applications of DSP devices

　　As DSP performance continues to improve, using DSP devices for real-time processing has become a new hot spot in current and future technological developments.

　　TI's latest TMS320C2XX series has a good performance-price ratio and can basically replace 16-bit single-chip microcomputers. Among them, the price of TMS320C203 is less than RMB 100, and the chip has a built-in 544-word high-speed SRAM. It can address 64K words of program/data and I/O externally, and the instruction cycle is between 25ns and 50ns. The real-time processing is more than twice faster than that of 16-bit single-chip microcomputers, and it can replace general single-chip microcomputers. In addition to the functions of TMS320C203, TMS320F206 has a built-in 32K word zero-wait flash memory, which can meet the requirements of single-chip design and minimize the size of user boards. The instructions and DSP core of TMS320F240 are fully compatible with TMS320C203 and F206. It has built-in 8K/16K word flash memory, two 10-bit A/Ds, each with a sampling frequency of up to 166kHz, 9 independent PWM outputs, built-in SCI and SPI interfaces, and built-in CAN bus interface. These greatly enhance the processing power of TMS320X240 and show strong vitality in the field of motor control. It is a typical user system of TMS320F240, which implements the following functions:

　　3-phase PWM output/3-phase current measurement/button control
LCD display/RS232 communication
A/D, D/A interface
62K word zero wait SRAM
Extended input, output and bidirectional I/O port/JTAG interface

in conclusion

　　The continuous improvement of DSP technology and the continuous introduction of various DSP devices will create an unprecedented broad space for the application of real-time digital signal processing. The design experience of single-chip microcomputer users in hardware and software can make it easy for them to upgrade from single-chip microcomputer to DSP.