One of the most common questions in interviews is how to calculate the depth of a FIFO. Fifo is used as buffering element or queueing element in the system, which is by common sense is required only when you slow at reading than the write operation.

FIFOs themselves can be made up of dedicated pieces of logic inside your FPGA or ASIC or they can be created from Flip-Flops (distributed registers). Which one of these two the synthesis tools will use is entirely dependent on the FPGA vendor …

A FIFO is a special type of buffer. The name FIFO stands for first in first out and means that the data written into the buffer first comes out of it first. There are other kinds of buffers like the LIFO (last in first out), often called a stack memory, and the shared memory.

We need to employ an asynchronous FIFO between two modules working at different clock domains when some amount of data has to be transmitted from one module to the other to avoid the data loss.

Apr 23, 2016 · Understand the behavior of a FIFO structure. Here you can find the architecture and an example of VHDL code of a FIFO in FPGA or ASIC.

Handshaking works great, but reduces bandwidth at the clock crossing interface because each piece of data has many cycles of series handshaking. Correctly designed FIFOs can increase bandwidth across the interface and still maintain reliable communication. FIFO is managed as a circular buffer using pointers. First write will occur at address 00h.

FIFOs are often used to safely pass data from one clock domain to another asynchronous clock domain. Using a FIFO to pass data from one clock domain to another clock domain requires multi-asynchronous clock design techniques. There are many ways to design a FIFO wrong.

Jul 6, 2018 · Indeed, in many ways an asynchronous FIFO is just like any other FIFO. Fig 1. A Basic synchronous FIFO. Let’s compare the two FIFOs with each other. Both a synchronous and asynchronous FIFOs have a write pointer. We’ll call this wbin. Then, on any write, we’ll increase this pointer by one–but only if the FIFO isn’t already FULL.

Apr 23, 2020 · Solve as many as the number of FIFO depth problems to clear the concept. Most of the semiconductor companies such as Analog Devices, Western Digital, and Nvidia, etc. which take a written-based test, will ask one FIFO depth question.

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