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Difference between SDAX/SCLX and SDA/SCL pin functions in LPC55xx?

Question asked by Arno Moonen on Jul 15, 2020
Latest reply on Jul 23, 2020 by Sebastián Del Río

We are currently developing a new product, based around the LPC55xx series.
I noticed that some pins can be configured as SDAX or as SDA, or similarly, SCLX or SCL.

However, looking in the user manual of the processor, it is not clear to me what the differences between these functions are.

I also noticed that the MCUXpresso Config Tool doesn't even mention the X (just show SCL and SDA).


 For example:

  • P0_13:
    • FUNC = 1: FC1_CTS_SDAX_SSEL0
    • FUNC = 5: FC1_RXD_SDA_MOSI
  • P0_14:
    • FUNC = 1: FC1_RTS_SCLX_SSEL1
    • FUNC = 6: FC1_TXD_SCL_MISO


Can someone explain to me what the difference is and why I should choose one over the other?