MCX MicrocontrollersのトピックRe: MCXE31B – Flashing via UART Without Using Debug Probe

MCXE31B Firmware Flashing Using SPI Without Debug Probe

blessyvinolin — Mon, 16 Feb 2026 06:50:58 GMT

Since MCX E31x devices do not support ISP mode and boot only from internal flash, is it possible to implement a custom SPI-based bootloader to enable firmware updates without using a debug probe? If yes, what are the required memory regions and boot configuration considerations?

Re: MCXE31B Firmware Flashing Using SPI Without Debug Probe

marek-trmac — Mon, 16 Feb 2026 08:32:05 GMT

Hi @blessyvinolin

ISP mode for MCXE31x is supported via flashloader application, which supports UART and SPI. The flashloader is by default present in flash and started in boot.

See details here: Processor-specific workflows — Secure Provisioning Tool 25.12

MCXE31B – Flashing via UART Without Using Debug Probe

blessyvinolin — Tue, 17 Feb 2026 06:41:51 GMT

Hi marek,

I am working with the MCXE31B and using the MCUXpresso Secure Provisioning Tool for flashing.

Current Setup:

flashloader.bin is first programmed into the device using a debug probe.
I have connected a USB-to-TTL converter to LPUART0.
After the flashloader is programmed, then the tool flash my application binary (led_blinky.bin) through UART.

Issue:

Whenever I power off or reset the board, the flashloader is no longer available, and I must again use the debug probe to flash flashloader.bin before I can program the application.

Is it possible to flash the application only using UART, without using the debug probe every time?

Can the internal ROM bootloader of MCXE31B be used for UART flashing?

What boot configuration is required to enable UART-only flashing?

Any guidance would be appreciated.

Thanks.

Regards,

Blessy

Re: MCXE31B – Flashing via UART Without Using Debug Probe

marek-trmac — Tue, 17 Feb 2026 07:22:28 GMT

Hi @blessyvinolin

> Can the internal ROM bootloader of MCXE31B be used for UART flashing? What boot configuration is required to enable UART-only flashing?

There is no bootloader in ROM of this device. The UART ISP (ISP = In System Programming mode) is supported via flashloader only.

> Is it possible to flash the application only using UART, without using the debug probe every time?

You can use another bootloader instead of the flashloader, that supports such feature. See for example MCUboot | mcuboot

Re: MCXE31B – Flashing via UART Without Using Debug Probe

blessyvinolin — Fri, 27 Feb 2026 07:47:14 GMT

How can I flash the image only using uart without using debug probe?

Re: MCXE31B – Flashing via UART Without Using Debug Probe

marek-trmac — Fri, 27 Feb 2026 07:58:13 GMT

Hi @blessyvinolin

> How can I flash the image only using uart without using debug probe?

Chips where debug probe is not needed: Processor-specific workflows — Secure Provisioning Tool 25.12

And chips where debug probe is needed: Processor-specific workflows — Secure Provisioning Tool 25.12

Re: MCXE31B – Flashing via UART Without Using Debug Probe

blessyvinolin — Fri, 27 Feb 2026 09:46:01 GMT

Hi Marek,

Currently, I am facing the following issue:

Whenever I power off or reset the board, I need to connect the debug probe to flash the flashloader first. After that, I am able to flash my application image using UART.

However, my requirement is:

I want to flash the MCXE31B directly using UART without connecting the debug probe every time after power-on or reset.

Regards,

Blessy

Re: MCXE31B – Flashing via UART Without Using Debug Probe

marek-trmac — Fri, 27 Feb 2026 09:55:17 GMT

Hi @blessyvinolin

once the chip is not in factory state, SEC tool does not support provisioning without debug probe.

You can implement your own application updates in your custom application, that was provisioned first time into empty processor.