What are the differences between cpld and fpga

The difference between cpld and fpga: 1. Structure; 2. Integration level; 3. Interconnection structure; 4. Application scope; 5. Configuration and security; 6. Timing delay. Detailed introduction: 1. Structure, the interior of CPLD is composed of programmable logic units, programmable interconnection and I/O units, and the interior of FPGA is composed of configurable logic blocks, programmable input/output blocks and programmable interconnection matrix; 2 , Integration level, the integration level of CPLD is usually low, and most of them are thousands or tens of thousands of gates in chip scale. In comparison, FPGA has a higher integration level and can reach higher scale, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

CPLD and FPGA have significant differences in many aspects.

1. Structure:

CPLD: CPLD (Complex Programmable Logic Device) is internally composed of programmable logic units, programmable interconnection and I/O units . Its structure is relatively simple, and it mainly implements logical functions through interconnection line resources of equal length.

FPGA: FPGA (field programmable gate array) is internally composed of configurable logic blocks (CLB), programmable input/output blocks (IOB) and programmable interconnect matrix. Its structure is more complex, using multi-section distributed interconnections of varying lengths. This interconnection method is characterized by flexible wiring, but the delay is related to system layout and wiring.

2. Integration level:

CPLD: The integration level of CPLD is usually low, and most of them are thousands or tens of thousands of gates in size.

FPGA: In contrast, FPGA has a higher degree of integration and can reach a higher scale, such as hundreds of thousands of gates.

3. Interconnection structure:

CPLD: CPLD uses interconnection line resources of equal length, which is characterized by equal delays.

FPGA: FPGA uses multi-segment distributed interconnections of varying lengths. It is characterized by flexible wiring, but the delay is related to system layout and wiring.

4. Application scope:

CPLD: CPLD is mainly used to implement combinational logic, such as data path, sequential logic, etc. In some applications, such as digital signal processing and artificial intelligence, CPLDs may not be as efficient as FPGAs.

FPGA: FPGA can implement both combinational logic and sequential logic, and can be used to implement more complex tasks such as microprocessors and digital signal processing (DSP) algorithms. In applications that require large amounts of data processing power, such as data-intensive applications, FPGAs often exhibit higher performance.

5. Configuration and security:

CPLD: The CPLD configuration chip exists, and the configuration will not be lost after power failure, so there is no need for an external configuration chip. Due to the existence of the configuration chip, the security of CPLD is relatively high.

FPGA: In actual use, FPGA can almost be said to have no limit on the number of configurations. However, since FPGA uses SRAM technology for configuration, the configuration will be lost after power off, so an external configuration chip is required. In addition, since the configuration data may be read, the confidentiality of FPGA is slightly worse than that of CPLD.

6. Timing delay:

CPLD: The continuous wiring structure of CPLD determines that its timing delay is uniform and fixed.

FPGA: The segmented wiring structure used by FPGA causes the delay to be unstable.

In addition to the differences mentioned above, CPLD and FPGA also have the following differences:

1. Programming methods: The programming methods of CPLD and FPGA are also different. CPLDs are usually programmed using hardware description languages ​​(such as VHDL or Verilog), while FPGAs can be programmed using hardware description languages ​​or high-level programming languages ​​(such as C/C).

2. Programming flexibility: FPGA has a more flexible programming method and can realize online programming and dynamic configuration. CPLD, on the other hand, needs to download the programming data to the chip before configuring it.

3. Power consumption: Because FPGA adopts a distributed structure, its power consumption is relatively high. The power consumption of CPLD is relatively low because it uses simple logic units and interconnection structures.

4. Reliability: Because FPGA uses volatile memory (such as SRAM) for configuration, its reliability is relatively low. CPLD uses non-volatile memory (such as EEPROM or Flash) for configuration, so its reliability is relatively high.

To sum up, the difference between CPLD and FPGA mainly lies in the structure, integration level, interconnection structure, application scope, configuration and security, and timing delay. When choosing which device to use, comprehensive considerations need to be made based on specific design requirements and application scenarios.

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