Unable to determine pinmux for SPI to Mikroe connector on FRDM-MCNX947 dev board

[ClarkS]

Background

• Board: FRDM-MCXN947 with MCX N947 microcontroller.
• Peripheral: Mikroe AD-SWIO Click (AD74412R) connected via mikroBUS connector (J3/J4).
• User manual: UM12018 FRDM-MCNX946 indicates CS, SCK, MISO, and MOSI are pins P3_23, P3_21, P3_22, and P3_20
• Schematic Reference: FRDM-MCXN947-SCH.pdf, (mikroBUS), shows the following:
  • J6-3 (CS) wire is labeled P3_23/ME_FC6_SPI_CS
  • J6-4 (SCK) wire is labeled P3_21/ME_FC6_SPI_CLK
  • J6-5 (MISO) wire is labeled P3_22/ME_FC6_SPI_MISO
  • J6-6 (MOSI) wire is labeled P3_20/ME_FC6_SPI_MOSI

Problem

On Data Sheet Reference: MCXNx4xDS.pdf, the pinmux tables for pins P3_23, P3_21, P3_22, and P3_20 do not show any mux assignments for signals CS, CLK, MISO, or MOSI. 

On a quick look, it appears the reference manual, MCXNx4xUM.pdf, shows the same information for the pins as the data sheet.

Assistance Requested

I am a new user of NXP MCUs and I am certainly not yet familiar with your documentation. Please help me identify how to configure the pinmux so SPI signals CS, CLK, MISO, or MOSI are sent to the Mikroe connector. Please reference the documentation I should use to obtain the correct pinmux settings. 

Thank you in advance!

FRDM-MCXN947 

[Celeste_Liu · Accepted solution]

Hello @ClarkS ,

Thanks for your post. For the content in schematic and UM12018:

• The J6-3 (CS) wire is labeled as P3_23/ME_FC6_SPI_CS.
• The J6-4 (SCK) wire is labeled as P3_21/ME_FC6_SPI_CLK.
• The J6-5 (MISO) wire is labeled as P3_22/ME_FC6_SPI_MISO.
• The J6-6 (MOSI) wire is labeled as P3_20/ME_FC6_SPI_MOSI.

The signal names ME_FC6_SPI_XXX above indicate that these pins belong to the SPI function of the FlexComm module (FC6).
The FlexComm module is a multi-function peripheral supported by MCXN947, which can be configured in modes such as SPI, I2C, and UART.
For example, ME_FC6_SPI_CLK represents the clock pin when the FlexComm 6 module is configured for SPI.

So in the pinmux of the datasheet and MCXNx4xUM.pdf, this can be seen. they are all multiplexed to ALT 3, as shown in the figure below.

For the specific content of FlexComm, you can refer to Chapter 66 in the Reference Manual.

I hope the above information helps you. If you have any further questions, please feel free to ask me.

Have a nice day!

Celeste

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[ClarkS]

Thank you for the quick and thorough reply. I really appreciate it.