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Elements inside CPLDs are Macrocells(combinational+sequential).Currently CPLDs have maximum of 1024 Macrocells( see Lattice semicondutor make).
Most of them are flash based and are reprogrammable.
Elements inside FPGAs are combinational cell and sequential cells. The Actel FPGAs are available as one time programmable and flash based reprogrammable also. The Xilinx and Altera FPGAs are S-RAM based. The currently available FPGAs have about 2 million gates capacity.
NO .. The Architecture of a CPLD is different of a FPGA
THE FPGA is like a chess board with every square being a"CELL"
You use a synthesis tool to design .The tools does the mapping of the logic functions in a process called routing .This is very sofisticated and complex . At the end you can generate a REPORT . That will tell you if the timings concerns are met. In a general maner you don't need to worry about the underlaying structure of the FPA .. only in very particular cases when you need to optimize the timing .. FPGA have thousands of gates .. so you are never short! On the other hand a pins can be configured as either an inpur or output or both!
CLPD are diffrent .They have some pins only inputs and some pins that are both . The pins that are inputs go through a CONNECTION MATRIX
that will be programmed by some soft either low or high level description language or schematic using "PRIMITIVES" . In CPLDs you have to be more aware of the internal architecture to get the best out of it :SPEED
But the propagation times are fixed and well known !
CPLD are better to be used when you need very fast logic requirements
like memory mapping in an address bus !
i think that is better taht you search in internet or in the forum about this.
The difference between FPGA and CPLd is no simple to explain in 2 words.
Every farm have products that are CPLD, CPLD-FPGA or FPGA or SOC.
Bye.
G.
The latest FPGA with multi-million gates from ACTEL, ALTERA and XILINX contain the PLLs for delay and different clock multiplication/phase generation and a separate Block of user configurable SRAM in addition to cominational and register logic are embedded.
Some of Xilinx (Vertex family) and Altera (Stratix family) FPGAs do have 16bitx16bit fixed point multipliers and adders for DSP applications. One doesn't find these features in CPLDs.
CPLD is flash memory based for configuration. It could run after power-up.
FPGA is SRAM memory based for configuration. It need to configure every time after power-up. It need external configuration memory.
dear elektron what do you say it not totlly true, infact lattice make devices FPGA that have a flsh on device and once dowloaded one time you need no other devices to reconfigure it.
Otherwise some FPGA as Actel or Quick logic are OTP.
Bye.
G.
FPGAs have higher logic density than CPLDs but have many disadvantages.
On every power-on FPGA configurtion SRAM need to be configured. Sometimes it makes significant power-on lattency. Also FPGAs are very sensitive on power supply glitches.
Delay times are very dependant on routing process and routing software and always unpredictable. Delay time optimization is difficult with FPGAs especially with large and complex designs.
FPGAs are very good solution for complex logic prototyping e.g. FIFOs, CACHE memories, dual port SRAM, CPU cores and SOCs.
For less complex high speed designs use CPLDs instead FPGAs.
The best way to think about FPGA's is to think about a Static RAM
For example for Xilinx XC4000 think for an Serial Static RAM programed in serial or in parallel mode via some protocols(see documentation)
The best way to think about CPLD's is to think about a Reprogramabale Nonvolatile Memory (Elash,EEprom etc) and is vendor dependent wich "type" of Reprogramabale Memory is used
For example mostly Altera CPLD's can be viewed as serial EEproms programed via JTAG (serial) or in paralel (by a paralel programer) etc
Of course, thats are chips at the boundary between FPGA and CPLDS (wich has both Volatile Memory and Reprogramable Nonvolatile Memory)
CPLDs are low-cost and non-volatile, but they are too inflexible for me. Too much like a big old PLD.
If I could buy Xilinx FPGAs with non-volatile config memory, I would never use a CPLD again.
A good way to learn the difference is to download something like Xilinx WebPack, and try implementing various designs into a CPLD and FPGA. Then examine the results.
As I know, CPLD's basic logic unit is product term, and use flash memory to store configuration data. FPGA's basic logic unit is look-up-table, it is RAM based, so a external nonvolatile memory is need to store the configuration data. Generally, FPGA has much more logic capability than CPLD and could be seen within complex applications.
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