The Serial Peripheral Interface Board(SPI board) is among the most commonly used interfaces between microcontrollers and peripheral ICs like sensors, ADCs, DACs, shift registers, SERVER RAM, and others.
This article gives a short explanation of the SPI board. It is followed by an overview of Server CPUs' SPI-enabled muxes and switches and how they aid in reducing the amount of digital GPIOs on a system board design.
SPI is an asynchronous, full-duplex master-slave-based interface. The master or slave is synchronized with the falling or rising clock edge.
Both slave and master can send data simultaneously. The SPI interface is available in 3-wire or four-Server Rack Cables. This article is focused on the well-known four-wire SPI interface and Server Network Interface Card.
I2C. The SPI protocol, also known as the serial peripheral interface, is an additional instance of a serial protocol that allows two devices to exchange and receive information.
The major differentiator in SPI in comparison to I2C is that SPI utilizes several extra wires, including direct data input and an output wire, instead of using the same I2C.
Also, there's a clock wire as in I2C; however, with SPI, it can utilize every speed that it wants between a few kilohertz or several hundred megahertz (if the hardware can support this!).
This allows the SPI protocol ideal for TFT displays which require vast amounts of information. With control over the clock's speed, it's possible to transfer whole image images from the screen to display.
SPI Board Data Transmission
To start SPI communication, the master must transmit the signal for the clock and then choose the slave by activating it to receive the CS signal.
The chip select signal is typically an active, low-level signal, so the master needs to make a logic zero on that signal to choose the slave.
SPI board is an all-duplex interface, meaning that both the master and slave can communicate data simultaneously through MISO and MOSI lines. MOSI or MISO lines, respectively.
When using SPI board communication, data is simultaneously transferred (shifted to SDO/MOSI bus) while also being received (the buses' data (MISO/SDI) is read-in or sampled).
The clock edge of the serial clock synchronizes the shift and sampling of data.
The SPI interface allows the user to select the falling or rising edge of the watch that will shift and sample the data. Refer to the datasheet for your device to determine the number of data bits that can be transmitted through SPI interface.
Clock Polarity and Clock Phase
In SPI board master mode, the master can choose the clock's polarity and clock phase. The CPOL button controls the stage of the signal in the idle step.
The idle state can be defined as the time when CS has reached high and is transforming into low during the beginning of the transmission, and also at the point when CS decreases and changes to high towards the end of the transmit.
The CPHA bit is used to select the clock's timing. Under the CPHA bit that is on the rise or fall edge of the watch can be utilized to sample or change the signal's frequency.
The master is required to choose the clock polarity and the clock phase by the needs of the slave. Based on your CPOL and CPHA bit choice, four SPI modes are accessible. Table 1 lists each of the SPI modes.