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=== SPI ===
SPI (Serial Peripheral Interface Bus) is a synchronous serial data link. Devices communicate in master/slave mode where the master device initiates the data frame. Multiple slave devices are allowed with individual slave select (chip select) lines. It can be fater than I2C protocol and it is uasully used i short distances, it uses CMOS level voltage (1V8). Omap have four SPIs: SPI1 supports up to four peripherals, SPI2 and SPI3 support up to two<br>peripherals, and SPI4 supports only one peripheral. Omap SPI is named McSPI.
Omap McSPI have the next caractheristics:
- Supports [http://en.wikipedia.org/wiki/Direct_memory_access DMA] for data transfer operations, for reduce CPU usage.<br>- Supports full duplex data transfer operations, <span lang="en" classid="short_textresult_box" idclass="result_boxshort_text"><span class="hps">simultaneous comunication between master and slave.</span></span><br>- Supports configuration of number of wordlength.<br>- Supports configuration of phase and polarity of the device functional clockfor each channel.<br>- Support configuration of the bitratefor each channel.Between 1.5 KHz and 48 MHz<br>
Omap McSPI peripheral use five signals:
- McSPI_CSO: Chip Select 0.<br> - McSPI_CS1: Chip Select 1.<br> - McSPI_SOMI: Slave output master input data.<br> - McSPI_SIMO: Slave input master output data.<br> - McSPI_CLK: Clock.<br>
[http://omappedia.org/wiki/Kernel_McSPI http://omappedia.org/wiki/Kernel_McSPI]
[[How to use SPI]]