topic Re: Issue with the example project “frdmmcxa346_smartdma_keyscan” in MCX Microcontrollers

Issue with the example project “frdmmcxa346_smartdma_keyscan”

Hathaway_Noa — Thu, 05 Feb 2026 08:27:04 GMT

After building the SDK (v25.12.00) for MCUXpresso IDE (v25.6) using the MCUXpresso SDK Builder and importing the example project “frdmmcxa346_smartdma_keyscan”, an error occurs when debugging on the FRDM-MCXA346 board, as shown in the figure below, and the debugger cannot be launched.

After rebuilding the project for Keil, the program can be downloaded and debugged normally using Keil. However, the key scanning implemented by the SmartDMA firmware is obviously too sensitive: even when no button is pressed, key events are continuously triggered, which does not match the behavior described in AN14770. When switching to a traditional approach where the CPU actively scans the keys in the main loop, the key state is read correctly.

I would like to ask:

Does the example project “frdmmcxa346_smartdma_keyscan” exhibit this issue when being debugged with MCUXpresso IDE?
Does NXP provide any tool that allows directly downloading a .hex file?
Is the overly sensitive key detection in the “frdmmcxa346_smartdma_keyscan” example caused by the SmartDMA firmware itself?

Additionally, the P3_28 and P3_27 pins used in the frdmmcxa346_smartdma_keyscan example are I2C pins. On the FRDM-MCXA346 board, these pins are connected to pull-up resistors R25 and R24, which I have already removed.

Re: Issue with the example project “frdmmcxa346_smartdma_keyscan”

carlos_o — Mon, 09 Feb 2026 17:26:08 GMT

Hi @Hathaway_Noa

Thank you for your post!

I was able to replicate the debugging issue of the example at MCUXpresso, I'll come with further information, thanks again for the report.

Regarding your question

Does NXP provide any tool that allows directly downloading a .hex file?

Are you referring to download a code to a board? if that is the case no, the only compatible formats are .bin, .axf and .sb

Re: Issue with the example project “frdmmcxa346_smartdma_keyscan”

carlos_o — Fri, 13 Feb 2026 18:46:26 GMT

Hi @Hathaway_Noa

There are 3 problems with the example

Flash driver is not set for this example.
- To fix this need to set manually the flash driver to use "MCXA3xx.cfx".
Flash size is not 4 byte align
- To fix this the size was changed to 0xfe000
Ram sections overlaps with Cstack
- To fix this the ram size in data section was change to 0x10000 and the ram CStack section location was changed to 0x20010000

All of the above has to be done in the project propertis in the" C/C++ build" in the "MCU Settings" and set the memory details to the changes mentioned above (See the reference image to set the memory configuration correctly).

After that changes are applied just make a clean and rebuild the project and that solves the problem.