What's the difference between SPI and QSPI?

[Enshuo]

Hi experts,
As far as I know, the major difference is the data rate. The data rate of SPI is 10-20Mbps, QSPI is four times to 80Mbps, but the clock frequency of them are the same 25Mhz. QSPI doesn't require CPU intervention.

If I change a flash from SPI to QSPI, what else should I take care of? QSPI has four more pins, etc. Software or firmware are needed to modify as well?

 

[KlausST]

Hi,

I assume you did not do an internet search "SPI vs QSPI"
Please clarify whether you mean Quad or Queud SPI. Just to be sure to talk about the same.

QSPI doesn't require CPU intervention.

This statement makes no sense. Some CPUs have
* no SPI at all
* SPI, but no QSPI (where bit banging QSPI cuses a lot more processing power than SPI)
* SPI as well as QSPI

Changing from SPI to QSPI in either case means you need
* a compatible master,
* a compatible slave,
* compatible wiring
* and the according software/firmware.

Klaus

 

[ads-ee]

Based on the OPs description he's referring to QuadSPI

The main differences is QuadSPI has four data pins and sends 4-bits at a time and is not compatible with SPI.

The first non-advert link from goolge explains it pretty well: https://embeddedinventor.com/quad-spi-everything-you-need-to-know/

 

[FvM]

QSPI usage makes only sense if it's supported by CPU hardware. If supported, it's only a bit of configuration. QSPI is e.g. regularly used for ESP32 flash and external RAM.

 

[malli_1729]

SPI/QSPI use only when Master(MCU/Processor) has supported it.
About speeds SPI can operate up to 133Mhz.

SPI is not having any specific standard where manufacturers can adhere like I2C/SMBus.
QSPI people will use when they need faster boot up times with Higher memories etc.