diff -r 578be2adaf3e -r 307f4279f433 Adaptation/GUID-99FC067C-0AED-5373-AF63-8DB7FF5C1F7E.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Adaptation/GUID-99FC067C-0AED-5373-AF63-8DB7FF5C1F7E.dita Fri Oct 15 14:32:18 2010 +0100 @@ -0,0 +1,69 @@ + + + + + +SPI Technology GuideThis document describes the Serial Peripheral Interface +(SPI) technology. The SPI devices are used for fast data exchange +between two or more peripherals. + +
Introduction

The SPI is a synchronous serial interface. The SPI supports full +duplex communication channel for the devices that use SPI interface. +The devices and peripherals that use the SPI interface are described +as SPI devices in this document.

+
Architecture

In the SPI bus one of the node must be a master device and one +or more slave devices. There can be only one slave active at a time. +The master device initiates and terminates communication between the +SPI devices. The SPI is a full duplex serial data communication. In +full duplex communication the data can be transferred between the +master and the slave devices simultaneously.

The SPI devices +can be configured as master or slave. The SPI bus contain four wires. +The first one is the serial clock signal sent by the master device +to the slave device. The clock signal is used for synchronisation. +The Master Output / Slave Input (MOSI) is used to +send data from the master to the slave. The Slave Output / Master +Input (SOMI) is used by the master device to read +data from the slave device. The fourth line is the Slave Select (SS) that is used by the master to select a slave to initiate +the communication.

+ SPI Bus + +
+
Communication

The master device is the node on the SPI bus that initiates and +terminates the communication. The master must provide the configuration +to the slave devices. The configuration includes the details like +the channel number and the data length. The SPI devices uses 4 and +8 bit words to communicate. If a slave device or a channel is not +available the appropriate error is returned to the master.

+
Advantages

The following are the advantages of the SPI interface:

    +
  • Full duplex +synchronous communication

  • +
  • Low power requirements +compared to the I2C devices

  • +
  • Less space compared +to the parallel bus

  • +
  • Slave devices +do not require unique address assigned

  • +
+
SPI +devices

Typically the SPI devices are used for data transfers +where a delay in the time taken to send the data is acceptable. The +clients of the SPI interface are device drivers running on the application +specific integrated circuits (ASIC). Some of the peripherals that +use SPI interface are:

    +
  • Touch screens

  • +
  • Codecs

  • +
  • Real Time Clocks

  • +
  • Built-in cameras

  • +
  • Flash memory +like MMC and SD cards

  • +
+
+IIC +Concepts +
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