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Is there a problem with SSP Data Size Select (DSS) in TI format

Question asked by Torbjørn Tvermosegaard on Oct 20, 2016
Latest reply on Oct 20, 2016 by Torbjørn Tvermosegaard

Using a LPC4357 I am reading data from a SPI device using the Texas Instruments frame format, in the SSP control register I have set Data Size Select (DSS) to 16-bit transfer and Frame Format (FRF) to TI.

Sampling on the falling edge of clock I would then expect 16 falling edges between falling and rising edge of the SSEL/FS but I only see 15 which messes up my readings, is this an error in the peripheral or have I missed something?

 

Screenshot of a supposedly 16-bit frame readout
SSP FRF DSS wrong frame size

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