SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 677

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

32. Serial Peripheral Interface (SPI) Programmer Datasheet
32.1
32.2
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
Description
Embedded Characteristics
The Serial Peripheral Interface (SPI) circuit is a synchronous serial data link that provides com-
munication with external devices in Master or Slave Mode. It also enables communication
between processors if an external processor is connected to the system.
The Serial Peripheral Interface is essentially a shift register that serially transmits data bits to
other SPIs. During a data transfer, one SPI system acts as the “master”' which controls the data
flow, while the other devices act as “slaves'' which have data shifted into and out by the master.
Different CPUs can take turn being masters (Multiple Master Protocol opposite to Single Master
Protocol where one CPU is always the master while all of the others are always slaves) and one
master may simultaneously shift data into multiple slaves. However, only one slave may drive its
output to write data back to the master at any given time.
A slave device is selected when the master asserts its NSS signal. If multiple slave devices
exist, the master generates a separate slave select signal for each slave (NPCS).
The SPI system consists of two data lines and two control lines:
• Master Out Slave In (MOSI): This data line supplies the output data from the master shifted
• Master In Slave Out (MISO): This data line supplies the output data from a slave to the input
• Serial Clock (SPCK): This control line is driven by the master and regulates the flow of the
• Slave Select (NSS): This control line allows slaves to be turned on and off by hardware.
• Supports Communication with Serial External Devices
• Master or Slave Serial Peripheral Bus Interface
• Connection to DMA Channel Capabilities Optimizes Data Transfers
into the input(s) of the slave(s).
of the master. There may be no more than one slave transmitting data during any particular
transfer.
data bits. The master may transmit data at a variety of baud rates; the SPCK line cycles once
for each bit that is transmitted.
– Four Chip Selects with External Decoder Support Allow Communication with Up to
– Serial Memories, such as DataFlash and 3-wire EEPROMs
– Serial Peripherals, such as ADCs, DACs, LCD Controllers, CAN Controllers and
– External Co-processors
– 8- to 16-bit Programmable Data Length Per Chip Select
– Programmable Phase and Polarity Per Chip Select
– Programmable Transfer Delay Between Consecutive Transfers and Delay Before SPI
– Programmable Delay Between Chip Selects
– Selectable Mode Fault Detection
– One channel for the Receiver, One Channel for the Transmitter
15 Peripherals
Sensors
Clock per Chip Select
SAM3X/A
SAM3X/A
677
677