Introduction
Hello, my name is Totto. and I am steadily accumulating knowledge of circuit boards as an engineer.
One day, I saw a senior engineer, Mr. Choucho, struggling to provide customer support for memory, and I wondered what kind of thing memory was.
I checked it out with a Beryll - Cyclone ® V GX base board.
However, there are so many devices on the board that I could not tell which one is the memory. I found that SRAM, DDR3, and EPCS are installed on the board.
- SRAM : IDT
As a new engineer, I was still confused when I saw this (・・・・・), so I decided to look into memory.
What is memory ・・・・
Memory is a place to store data.
The following are typical types of memory.
(Note: The above figure is an example.
EPCS ROM and EPCQ ROM/EPCQA ROM used in Intel FPGA device configuration are classified as FLASH ROM in the above figure.
The senior engineer, Mr. Choucho was struggling with a memory called DDR3-SDRAM, which is classified as DRAM in the above figure.
So I decided to look into DDR3-SDRAM.
Position of DDR3 among DRAMs
The following chart shows how DDR3 is positioned in DRAMs.
The data transfer rate is getting faster with each new generation.
- SDR stands for Single Data Rate.
- Data is transferred at the rising or falling edge of the clock.
- DDR is an abbreviation for Double Data Rate.
- Data is transferred on both the rising and falling edges of the clock.
Role of DDR3-SDRAM for FPGA
- Temporarily stores data to be processed by the FPGA. (Write)
- Reads temporarily stored data and processes the data in the FPGA. (Read)
Small talk
I : "Temporary storage? What's the difference from storing data in HDD? I asked my senior.
He said: "When you interface FPGA and HDD, it takes longer time to process data than RAM or ROM.
I : "That's why HDD works slowly when it works as virtual memory in a PC! I was convinced.
By the way, what is the principle of DDR3-SDRAM read/write operation?
Summary of this article
- Memory is a place to store data
- DDR3-SDRAM temporarily stores FPGA data.
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