In these days fast developing technologies in Japan, there have been so many things that are happening that most people wouldn’t really care about. However, most these things are very important for Engineers and software developers. They need to consider the right digital chips. Two of the most popular digital logic chips are the Field-Programmable Gate Array FPGA, and the Complex Programmable Logic Device CPLD. An example of the FPGA is the Altera FPGA. The two chips differ greatly when it comes to their internal architecture. Especially the Altera FPGA, it is very different with CPLD when it comes to the internal architecture.
Here are the definitions of each of these logic chips:
FPGA. This programmable logic chip is a chip that can be programmed to do almost every kind of digital functions. The architecture of the FPGA can give the chip a very high logic capacity to perform so many functions. The FPGA is used for designs that have very high gate count. If the designs have so many unpredictable delays because of its architecture, FPGA chips are best used for them. FPGA has 100,000 tiny logic blocks, which is why it is considered as a “fine grain.” FPGA is made for the more complex applications. Because of its complex structure, FPGA are more expensive than CPLD. FPGA is RAM-based. Because of this, it needs special procedures to program. In programming the device, you have to describe its “logic function” using the computer first. You can do this by drawing a schematic or simply describe the functions on a text file. To aid software, “logic file” are usually needed. It makes a binary file, which will be downloaded on your FPGA. This way, your chip will perform functions as you program it to do.
CPLD. These logic chips are made up using EEPROM. This chip is used for small gate designs. This is not volatile and delays are predictable because its architecture is not that complex. This chip is often used for simple logic applications only. Unlike the FPGA with 100,000 logic blocks, CPLD only has a hundred or less, which is why it is considered to be a “coarse grain” device. Because of this, it provides a faster input to output duration. The CPLD are also much cheaper compared with FPGA because it is much simpler in architecture.
These are the main definition and the main difference between the FPGA and the CPLD. You must know your goal, what programs you will do and what functions you need your chip to perform in deciding which of the two you will use. If you are planning to perform a bigger logic function, then you need something with a more complex function with more logic blocks and this is the FPGA. If you are just going to create a design that needs to perform a small logic function, then you need something simpler and faster with only less logic block and this is the CPLD. You will not need much budget for the latter too.
