While operations depend on the logical relationship between the input and the output, a logic gate processes signals that represent a true or false state.ĭuring the 1990s, gate arrays were the rage-at least in electronic design. In the simplest form, a logic gate has one or more inputs and one output. Logic gates form the basic foundation of any digital system. Whether designed by a farmer or an engineer, gates perform the same function by simply changing the status of something. By the end of my years working at the store, I was armed with the curiosity and adaptability required of engineers, and an appreciation of how important a quality gate is. Most of the store’s sales were to hardworking farmers, looking to build solid gates. To my surprise, working in the store was excellent preparation for my future career in electronics. #Fpga how it works softwareOne of the very interesting things about FPGAs is that while you are designing the hardware, you can design the hardware to be a processor that you then can write software for! In fact, companies that design digital circuits, like Intel or nVidia, often use FPGAs to prototype their chips before creating them.Gate arrays used in the 1990s are considered costly and clunky, given the resources needed to design a complex integrated circuit.įPGAs were introduced as a modern, flexible solution to older, more traditional logic gates.įPGAs allow designers to amplify performance and effectiveness while conserving power.Īfter graduating from high school, I applied to work at a local hardware store. Just like microcontrollers that have a set amount of memory for your program, FPGAs can only emulate a circuit so large. The only limitations you really have are the number of physical I/O pins and the size of the FPGA. #Fpga how it works serialThat also means you can create as many serial ports as you want. With an FPGA you are able to create the actual circuit, so it is up to you to decide what pins the serial port connects to. If you want to emulate more than one port then you end up using all your processor time. That works fine except you are wasting valuable processor time with the very basic task of sending out bits. If you want more than one serial port, or you want to use some other pins, your only solution besides getting a different chip is to use software to emulate a serial port. For example there will be only two pins on some microprocessors that are used as a serial port. With a typical microprocessor, you have dedicated pins for specific features. With FPGAs you have control over the hardware. There are also some development boards which don't require a programmer at all and will configure the FPGA at startup. That is not as bad as it seems as there are flash chips you can use that will automatically configure the stored bit file on power up. They must be configured every time power is applied. A slight downside to FPGAs is that they store their configuration in RAM, not flash, meaning that once they lose power they lose their configuration. You then synthesize your HDL into a bit file which you can use to configure the FPGA. The two most popular HDLs are Verilog and VHDL. To create your design, you write some HDL ( Hardware Description Language). There is no processor to run software on, at least until you design one! You can configure an FPGA to be something as simple as an and gate, or something as complex as a multi-core processor. With microcontrollers you have control over the software.įPGAs are different. The microcontroller stores the program in flash memory and will store it until it is erased or replaced. You simply write some software, usually in C or C++, and compile it to a hex file that you load onto the microcontroller. With a microcontroller, like an Arduino, the chip is already designed for you. So first it is important to understand that they are very different devices. When I first learned about FPGAs, all I really knew about before was microcontrollers. One of the reasons FPGAs are so awesome is that unlike an ASIC ( Application Specific Integrated Circuit) the circuit design is not set and you can configure an FPGA as many times as you like! Creating an ASIC also costs potentially millions of dollars and takes weeks or months to create. Once loaded the FPGA will behave like the digital circuit you designed! It is up to you (the designer) to create a configuration file, often called a bit file, for the FPGA. You can think of an FPGA as a blank slate. The cost has come down enough that you don't have to be a huge company to get your hands dirty. Either way, FPGAs ( Field Programmable Gate Arrays) are amazing devices that now allow the average person to create their very own digital circuits. So what exactly is an FPGA? You may have heard the term thrown around, or maybe you have no idea what I'm talking about.
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