Single vs. Dual vs. Quad SPI | Differences & Similarities

 

The SPI Bus Protocol 

SPI, Serial Peripheral Interface Bus, is a synchronous serial data protocol that was developed by Motorola in the 1970s. The protocol was developed to replace parallel buses and provide high-speed data transfers over short distances.

It is a full duplex protocol that requires four signals: clock, master out / slave in, master in / slave out, and slave select. Data is sent and received at the same time. With SPI, multiple slave devices can be controlled by a single master, and each slave device has its own slave selection line.

 

Master_Slave_spi

 

 

 

 

The differences between single, dual and quad SPI

 

 

Single SPI

Single-mode SPI is suitable for most use cases such as rapid prototyping, device programming, and automated testing. SPI is fast, with most single SPI serial throughput rates reaching around 10 Mbps. The parallel throughput rates for individual SPI are between 10 and 24 Mbit / s.However, a single data line cannot send data at the fastest speed of SPI.

 

 

Dual SPI 

Dual SPI has a dual I / O interface that can double the transfer rates compared to standard serial flash memory devices. The MISO and MOSI data pins operate in half-duplex mode to send two bits per clock cycle. The MOSI line becomes IO0 and the MISO line becomes IO1. The serial dual SPI throughput rates reach around 20 Mbit / s.

 

 

 

 

Quad SPI

Quad SPI is similar to Dual, but improves throughput by four times. Two additional data lines are added and 4 bits are transferred on each clock cycle. The data lines are now IO0, IO1, IO2 and IO3. The serial Quad SPI throughput rates reach around 40 Mbit / s.
 
 
Quad_SPI_Setup

 

 

Benefits of Dual and Quad SPI

Multi I / O SPI is particularly useful with memory-intensive data. Compared to classic SPI, in which only one data line is used, dual and quad SPI use two and four data lines, which increases the data throughput two or four times.

Prior to the creation of dual and quad SPI, previous solutions used parallel storage. The parallel memory would use 8, 16 or 32 pin to connect the external storage device to the microcontroller. Compared to parallel interfaces, external flash memory chips can be delivered in smaller packages with dual and quad SPI. These small packages reduce the board space, which simplifies PCB design and reduces GPIOs.

The decision to use Dual or Quad SPI is based on the number of pins and the data rate that developers want to use. Flash chips that support Quad SPI generally support Dual SPI. Single, dual and quad SPI are also pin compatible. Further information on the flash chip can be found in the respective data sheet.

 

 

 

 

 

The differences between single, dual and quad SPI

 

 

Single SPI

Single-mode SPI is suitable for most use cases such as rapid prototyping, device programming, and automated testing. SPI is fast, with most single SPI serial throughput rates reaching around 10 Mbps. The parallel throughput rates for individual SPI are between 10 and 24 Mbit / s.However, a single data line cannot send data at the fastest speed of SPI.
 

 

 

Dual SPI 

Dual SPI has a dual I / O interface that can double the transfer rates compared to standard serial flash memory devices. The MISO and MOSI data pins operate in half-duplex mode to send two bits per clock cycle. The MOSI line becomes IO0 and the MISO line becomes IO1. The serial dual SPI throughput rates reach around 20 Mbit / s.

 

 

 

 

Tools that support various SPI configurations

The Aardvark I2C / SPI host adapter, Cheetah SPI host adapter, and Beagle I2C / SPI protocol analyzer support SPI single I / O. The Promira Serial Platform supports single, dual or quad I / O depending on the SPI application.

 

 

 

promira_card

 

Promira Serial Platform

The Promira ™ Serial Platform is a powerful platform that is connected to the host PC via USB. The Promira platform also enables remote control for automations and can supply the target IC with up to 200 mA of current. Different applications are available for I2C, SPI and eSPI with different performance specifications that can be expanded as required.

aardvark_promote

 

Aardvark I2C / SPI Adapter

The Aardvark I2C / SPI host adapter is connected via USB and is a powerful and fast I2C and SPI host adapter. Developers can connect a Mac, Linux computer or Windows PC to the embedded system environment and transfer the serial data streams using the I2C and SPI protocols.

beagle_spi_card

 

Beagle I2C Protocol Analzer

The versatile Beagle I2X protocol analyzer is the ideal tool for the embedded technician developing an SPI-based product. In addition to I2C, the SPI and MDIO communication protocol are also supported. With the powerful data center software and the combination of the internal memory of the Beagles SPI protocol analyzer, all incoming data can be recorded in real time.