SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
In master mode (MASTER_SLAVE = 1), the SPI provides the serial clock on the SPICLK pin for the entire serial communications network. Data is output on the SPISIMO pin and latched from the SPISOMI pin.
The SPIBRR register determines both the transmit and receive bit transfer rate for the network. SPIBRR can select 125 different data transfer rates.
Data written to SPIDAT or SPITXBUF initiates data transmission on the SPISIMO pin, MSB (most-significant bit) first. Simultaneously, received data is shifted through the SPISOMI pin into the LSB (least- significant bit) of SPIDAT. When the selected number of bits has been transmitted, the received data is transferred to the SPIRXBUF (buffered receiver) for the CPU to read. Data is stored right-justified in SPIRXBUF.
When the specified number of data bits has been shifted through SPIDAT, the following events occur:
In a typical application, the SPISTE pin serves as a chip-enable pin for a SPI slave device. This pin is driven low by the master before transmitting data to the slave and is taken high after the transmission is complete.
Figure 17-5 is a block diagram of the SPI in master mode. The block diagram shows the basic control blocks available in SPI master mode.