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

[airios_arno]

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?

[airios_arno]

So there are two ways to configure these pins to the exact same configuration? I would not have expected that.

[Sebastian_Del_Rio]

Hi Arno,

I hope this helped, please let me know if you need any more information.

Best regards,

Sebastian

[Sebastian_Del_Rio · Accepted solution]

Hi Arno, I hope you're doing well!

The two names serve to identify either the SCL and SDA signals of the I2C bus, however, the "X"s on the names appear to be a mistake, according to tables 595 and 591 of the LPC55xx User Manual:

Please let me know if you need any more information.

Best regards,

Sebastian

[danielholala]

The two names serve to identify either the SCL and SDA signals of the I2C bus, ...

@Sebastian_Del_Rio , so you are saying that to configure SDA for, e.g., P0_13, one can either select FUNC = 1 

danielholala_0-1683900911462.png

or select FUNC = 5:

danielholala_2-1683901064601.png

Please confirm that both configurations are equivalent.

I ran into this issue recently and I have to say that this redundancy is clearly unexpected and left me puzzled.

Thanks.
Dan