A register is just a byte of microcontroller memory that can be read from or written to. These modes control whether data is shifted in and out on the rising or falling edge of the data clock signal, and whether the clock is idle when high or low.Īll SPI settings are determined by the Arduino SPI Control Register (SPCR). Generally speaking there are three modes of transmission numbered 0 - 3. This means you have to pay special attention to the datasheet when writing your interface code. The difficult part about SPI is that the standard is loose and each device implements it a little differently. See the table below to understand the new terminology: Master/Slave (OLD) Arduino no longer supports the use of this terminology. Serial Clock (SCK) - The clock pulses which synchronize data transmission generated by the Controller, andĬhip Select pin (CS) - allocated on each device which the Controller can use to enable and disable specific devices and avoid false transmissions due to line noise.Ĭontroller/peripheral is formerly known as master/slave. Typically there are three lines common to all the devices:Ĭontroller In, Peripheral Out (CIPO) - The Peripheral line for sending data to the Controller,Ĭontroller Out Peripheral In (COPI) - The Controller line for sending data to the Peripherals, With an SPI connection there is always one Controller device (usually a microcontroller) which controls the peripheral devices. It can also be used for communication between two microcontrollers. Serial Peripheral Interface (SPI) is a synchronous serial data protocol used by Microcontrollers for communicating with one or more peripheral devices quickly over short distances. Arduino Microcontroller ( Link to store).AT25HP512 Serial EEPROM chip (or similar).Enable SPI communication between an EEPROM chip and the Arduino.Note that the chip on the Arduino board contains an internal EEPROM, so follow this tutorial only if you need more space than it provides. EEPROM chips such as this are very useful for data storage, and the steps we will cover for implementing SPI communication can be modified for use with most other SPI devices. In this tutorial you will learn how to interface with an AT25HP512 Atmel serial EEPROM using the Serial Peripheral Interface (SPI) protocol.

Arduino serial port settings