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RM0090: Reference manual - STMicroelectronics

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<strong>RM0090</strong> Serial peripheral interface (SPI)<br />

SPI TI protocol in master mode<br />

In master mode, the SPI interface is compatible with the TI protocol. The FRF bit of the<br />

SPI_CR2 register can be used to configure the master SPI serial communications to be<br />

compliant with this protocol.<br />

The clock polarity and phase are forced to conform to the TI protocol requirements whatever<br />

the values set in the SPI_CR1 register. NSS management is also specific to the TI protocol<br />

which makes the configuration of NSS management through the SPI_CR1 and SPI_CR2<br />

registers (SSM, SSI, SSOE) transparent for the user.<br />

Figure 275: TI mode - master mode, single transfer and Figure 276: TI mode - master mode,<br />

continuous transfer) show the SPI master communication waveforms when the TI mode is<br />

selected in master mode.<br />

Figure 275. TI mode - master mode, single transfer<br />

Figure 276. TI mode - master mode, continuous transfer<br />

NSS<br />

output<br />

SCK<br />

output<br />

MOSI<br />

output<br />

MISO<br />

intput<br />

NSS<br />

output<br />

SCK<br />

output<br />

MOSI<br />

input<br />

MISO<br />

output<br />

trigger<br />

edge<br />

sampling trigger<br />

edge edge<br />

sampling<br />

edge<br />

trigger<br />

edge<br />

sampling<br />

edge<br />

DONTCARE MSBIN<br />

LSBIN DONTCARE<br />

1 or 0 MSBOUT LSBOUT<br />

trigger sampling trigger sampling trigger sampling<br />

DONTCARE MSBOUT<br />

LSBOUT<br />

1 or 0 MSBIN LSBIN<br />

MSBOUT LSBOUT<br />

MSBIN LSBIN<br />

FRAME 1 FRAME 2<br />

ai18436<br />

DONTCARE<br />

ai18437<br />

Doc ID 018909 Rev 3 800/1416

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