SPI

How it is used

Pronounced 'S-P-I', sometimes 'spy'. The lines are usually called SCLK, MOSI, MISO and CS (chip select); newer documents may use SDO and SDI. Engineers talk about the SPI mode (clock polarity and phase), the SPI clock speed and pulling CS low to start a transfer.

Example sentences

1. The display runs on SPI at 20 MHz, so we can refresh it quickly.

2. The flash chip ignores our commands because the SPI mode is wrong.

Common collocations

• SPI bus
• SPI mode
• chip select
• SPI flash
• SPI clock

Related terms

• I2CA two-wire serial bus, with a data line (SDA) and a clock line (SCL), that lets a microcontroller talk to many chips, each with its own address. It is common for sensors, EEPROMs and small displays.
• UARTShort for universal asynchronous receiver-transmitter: a hardware block that sends and receives serial data over two lines, TX and RX, without a shared clock.
• clock signalA regular square wave that sets the timing of a digital circuit so that all its parts act in step. Its frequency, for example 16 MHz, sets how fast a processor runs.
• microcontrollerA small computer on a single chip, with a processor, memory and input/output peripherals. It runs firmware to control devices such as appliances, sensors and motors.
• ADCShort for analog-to-digital converter: a circuit that measures an analog voltage and turns it into a number a processor can use. Its resolution is given in bits, for example 12-bit.

More terms: Digital Electronics and Microcontrollers

• GPIO
• PWM
• firmware
• pull-up resistor