SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
Continuous transfers are allowed manually by keeping the SPIEN[x] signal active for successive SPI words transfer. Several sequences (configuration/enable/disable of the channel) can be run without deactivating the SPIEN[x] line. This mode is supported by all channels and any master sequence can be used (transmit-receive, transmit-only, receive-only).
Keeping the SPIEN[x] active mode is supported when:
The state of the SPIEN[x] signal is programmable:
When the channel is enabled, the SPIEN[x] signal activates with the programmed polarity. As in the multichannel master mode, the transfer start depends on the status of the MCSPI_TXx register (the MCSPI_CHxSTAT[1] TXS bit), the status of the MCSPI_RXx register (the MCSPI_CHxSTAT[1] RXS bit), and the defined mode (the MCSPI_CHxCONF[13:12] TRM bit field) of the channel enabled.
The MCSPI_CHxSTAT[2] EOT bit gives the transfer status of each SPI word. The RXx_FULL bit in the MCSPI_IRQSTATUS register is set when received data is loaded from the shift register to the MCSPI_RXx register.
A change in the configuration parameters is propagated directly on the SPI interface. If the SPIEN[x] signal is activated, ensure that the configuration is changed only between SPI words to avoid corrupting the current transfer.
To avoid data corruption, SPIEN polarity and SPICLK phase and SPICLK polarity must not be modified when the SPIEN[x] signal is activated.
A delay between SPI words that requires the connected SPI slave device to switch from one configuration to another (for instance, from transmit-only to receive-only) must be handled by software.
At the end of the last SPI word, the channel must be deactivated (the MCSPI_CHxCTRL[0] EN bit set to 0) and SPIEN[x] can be forced to its INACTIVE state using the MCSPI_CHxCONF[20] FORCE bit.
Figure 26-85 and Figure 26-86 show successive transfers with SPIEN[x] maintained active low with a different configuration for each SPI word in single-data-pin and dual-data-pin interface modes, respectively.
The SPIEN[x] signal can be maintained active via software using the MCSPI_CHxCONF[20] FORCE bit only when the MCSPI_MODULCTRL[0] SINGLE bit is set to 0x1.