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S3FN429_UM_REV1.20 15 Serial Peripheral Interface (SPI) 15.2.2.1.3.13 Examples of Master and Slave Configurations PrimeCell SSP (PL022) peripheral can be connected to other synchronous serial peripherals when it is configured as a master or a slave. NOTE: The SSP (PL022) does not support dynamic switching between master and slave in a system. Each instance is configured and connected either as a master or as a slave. Figure 15-8 and Figure 15-9 illustrates PrimeCell SSP master coupled to two slaves and SPI master coupled to two PrimeCell SSP slaves respectively. SPI Slave PL022 Configured as Master SSPTXD MOSI SSPRXD MISO SSPFSS SCK SSPCLK SS 0V SPI Slave MOSI MISO SCK SS 0V Figure 15-8 PrimeCell SSP Master Coupled to Two Slaves The PrimeCell SSP (PL022) is configured as master, and is interfaced to two Motorola SPI slaves. Each SPI Slave Select (SS) signal is permanently tied LOW and configures them as slaves. Similar to the above operation, the master can broadcast to two slaves through the master PrimeCell SSP SSPTXD line. In response, only one slave drives its SPI MISO port onto the SSPRXD line of the master. 15-15
