SPI Frame delays

Several delays can be specified for SPI frames. These include:

  • Pre_delay: delay after SSEL is asserted before data clocking begins
  • Post_delay: delay at the end of a data frame before SSEL is deasserted
  • Frame_delay: delay between data frames when SSEL is not deasserted
  • Transfer_delay: minimum duration of SSEL in the deasserted state between transfers

Pre_delay and Post_delay

Pre_delay and Post_delay are illustrated by the examples in c-Framedelays.html#d17e1874__BGBDFDAH. The Pre_delay value controls the amount of time between SSEL being asserted and the beginning of the subsequent data frame. The Post_delay value controls the amount of time between the end of a data frame and the deassertion of SSEL.



Pre_delay and Post_delay timing

Frame_delay

The Frame_delay value controls the amount of time at the end of each frame. This delay is inserted when the EOF bit = 1. Frame_delay is illustrated by the examples in c-Framedelays.html#d17e1874__BGBJCFGJ. Note that frame boundaries occur only where specified. This is because frame lengths can be any size, involving multiple data writes. See SPI Data lengths greater than 16 bits for more information.



Frame_delay timing

Transfer_delay

The Transfer_delay value controls the minimum amount of time that SSEL is deasserted between transfers, because the EOT bit = 1. When Transfer_delay = 0, SSEL may be deasserted for a minimum of one SPI clock time. Transfer_delay is illustrated by the examples in c-Framedelays.html#d17e1874__BGBGGEGD.



Transfer_delay timing


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