FRDM MCXN947 - question about uart pins for MCU-Link and MCXN947

stejen — Tue, 17 Jun 2025 11:23:57 GMT

Hello

I have a FRDM MCXN947 dev board. I have read the user manual for it and looked over the schematics.

As I understand, the UART Pins (RX/TX) of the MCU-Link (LPC55S69JEV98) are connected to the pins P1_9 / P1_8 of the target MCU MCXN947

So I thought, when in ISP Mode, I could use that to flash the debugger.

Next, when I looked over the hello world example, the MCXN947 P1_9 / P1_8 pins are ALSO used for UART. This time for outputting hello world.

Are those pins used for BOTH debug AND target MCU UART? Or am I wrong that I could use those pins for flashing the debugger?

And if used for both, do I have to switch something before using it for one or the other (maybe in non-isp mode of the debugger those pins are not connected/used on the debugger side)

Would be nice if anyone could shed light on this topic

Regards stejen

Re: FRDM MCXN947 - question about uart pins for MCU-Link and MCXN947

diego_charles — Fri, 20 Jun 2025 23:32:27 GMT

hi @stejen

Regarding Are those pins used for BOTH debug AND target MCU UART?

Yes, you are correct. You do not need to configure anything else for the pins for UART debug and then communication over UART during ISP programming.

Let me know if you have any other question.

Diego

topic FRDM MCXN947 - question about uart pins for MCU-Link and MCXN947 in MCX Microcontrollers

FRDM MCXN947 - question about uart pins for MCU-Link and MCXN947

Re: FRDM MCXN947 - question about uart pins for MCU-Link and MCXN947