8.3.8.3.4 Transfer Delays

The figure below shows a chip select transfer change and consecutive transfers on the same chip select. Three delays can be programmed to modify the transfer waveforms:

  • The delay between the chip selects. It is programmable only once for all chip selects by writing the FLEX_SPI_MR.DLYBCS field. The SPI client device deactivation delay is managed through DLYBCS. If there is only one SPI client device connected to the host, the DLYBCS field does not need to be configured. If several client devices are connected to a host, DLYBCS must be configured depending on the highest deactivation delay. Refer to “SPI Timings” in the section “Electrical Characteristics”.
  • The delay before SPCK, independently programmable for each chip select by writing the DLYBS field. The SPI client device activation delay is managed through DLYBS. Refer to “SPI Timings” in the section “Electrical Characteristics” to define DLYBS.
  • The delay between consecutive transfers, independently programmable for each chip select by writing the DLYBCT field. The time required by the SPI client device to process received data is managed through DLYBCT. This time depends on the SPI client system activity.

These delays allow the SPI to be adapted to the interfaced peripherals and their speed and bus release time.

Figure 8-90. Programmable Delays