A New Method of Expanding SRAM Externally in MCU

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A New Method of Expanding SRAM Externally in MCU [Copy link]

Most MCUs have very limited on-chip SRAM resources, only tens of KB, and 256KB is already very luxurious. SRAM is much faster than NAND or NOR flash memory, and there is no limit on the read and write life, so it is irreplaceable as a high-speed data storage. However, due to the limited number of MCU pins, a parallel interface SRAM or SDRAM requires 3 to 40 package pins, so many MCUs do not have the ability to expand SRAM. Serial SRAM is a solution, however, SRAM is expensive, and serial SRAM is even more expensive. Here we introduce a PSRAM, which can be expanded as long as there is an SPI interface or QPI interface. PSRAM - Pseudo SRAM is a memory with an SRAM interface protocol (no refresh, no DRAM controller required) and a DRAM single-tube storage structure. It has a much larger capacity than SRAM, is much cheaper, is easier to use than SDRAM, and consumes much less power. Therefore, it has been supported by more and more MCU and WiFi-SoC related manufacturers. An 8-pin SOP-8 packaged SPI/QPI PSRAM can provide 4MB capacity and up to 50MB/s bandwidth. It can be used as long as it has an SPI or QPI interface. A 13-pin OPI PSRAM can provide a data throughput rate of 400MB/s or 3.2Gbps. At present, the main applications are 2G BB SIP (MXK, SPXD, RXA), intelligent voice interaction, GUI animation display storage of wearable devices, image data caching and other applications. The serial PSRAM capacity ranges from 2MB to 8MB, and the parallel PSRAM capacity ranges from 4MB to 16MB.