LPC MicrocontrollersのトピックRe: [LPC55S69] Zephyr MCUboot for Device Firmware Update Over UART Not Working with MCUmgr on LPC55S

[LPC55S69] Zephyr MCUboot for Device Firmware Update Over UART Not Working with MCUmgr on LPC55S69

ZQ2 — Tue, 04 Aug 2026 18:11:09 GMT

Hi, I've been trying to get Zephyr's MCUboot to work on the LPC55XpressoS69 using core 0. I am running the simple Blinky sample application in Zephyr.

Running the application just fine without any errors.

However, I've been trying to send a device firmware update (DFU) over UART using mcumgr and for some reason I can't even establish a connection between mcumgr and my device. I keep getting a "NMP timeout."

For context, my directory structure looks like the following:

|
__boards

|__ lpcxpresso55s69_lpc55s69_cpu0.overlay
__ src
|__main.c
__sysbuild
|__mcuboot.conf

__mcuboot.overlay
__prj.conf

__sysbuild.conf

My prj.conf looks as follows:

# Enable MCUMGR subsystem and OS/Image management commands CONFIG_MCUMGR=y CONFIG_MCUMGR_GRP_OS=y CONFIG_MCUMGR_GRP_IMG=y # DIRECT SMP over UART CONFIG_MCUMGR_TRANSPORT_UART=y CONFIG_MCUMGR_TRANSPORT_SHELL=n # Dedicate flexcomm0 to SMP — nothing else on the UART CONFIG_CONSOLE=n CONFIG_UART_CONSOLE=n CONFIG_LOG=n CONFIG_SERIAL=y CONFIG_UART_INTERRUPT_DRIVEN=y # Required for SMP UART processing thread CONFIG_NET_BUF=y CONFIG_ZCBOR=y CONFIG_BASE64=y # Required subsystems for DFU CONFIG_FLASH=y CONFIG_IMG_MANAGER=y CONFIG_MCUBOOT_IMG_MANAGER=y # Dependencies for System/Reboot management via DFU CONFIG_REBOOT=y

My sysbuild.conf is as follows:

SB_CONFIG_BOOTLOADER_MCUBOOT=y SB_CONFIG_MCUBOOT_MODE_OVERWRITE_ONLY=y

My mcuboot.conf looks like

CONFIG_LOG=y CONFIG_MCUBOOT_LOG_LEVEL_INF=y CONFIG_MCUBOOT_SERIAL=y CONFIG_BOOT_SERIAL_UART=y CONFIG_UART_CONSOLE=n

My mcuboot.overlay looks like

/* Step 3.4 - Configure button and LED for Serial Recovery */ // zephyr,console = &flexcomm0; // zephyr,uart-mcumgr = &flexcomm0; / { chosen { zephyr,code-partition = &boot_partition; zephyr,uart-mcumgr = &flexcomm0; zephyr,shell-uart = &flexcomm0; }; }; &flexcomm0 { status = "okay"; }; / { aliases { mcuboot-button0 = &user_button_3; mcuboot-led0 = &blue_led; }; }; &gpio0 { status = "okay"; }; &gpio1 { status = "okay"; }; &blue_led { status = "okay"; }; /* Enlarge boot partition to 64KB to fit MCUboot with serial recovery */ &boot_partition { reg = <0x00000000 DT_SIZE_K(64)>; }; &slot0_partition { reg = <0x00010000 DT_SIZE_K(160)>; }; &slot1_partition { reg = <0x00038000 DT_SIZE_K(160)>; }; &storage_partition { reg = <0x00060000 DT_SIZE_K(50)>; };

And finally my lpcxpresso55s69_lpc55s69_cpu0.overlay looks like

/ { chosen { zephyr,code-partition = &slot0_partition; zephyr,mgmt-smp = &flexcomm0; zephyr,uart-mcumgr = &flexcomm0; }; }; &flexcomm0 { status = "okay"; }; /* Enlarge boot partition to 64KB to fit MCUboot with serial recovery */ &boot_partition { reg = <0x00000000 DT_SIZE_K(64)>; }; &slot0_partition { reg = <0x00010000 DT_SIZE_K(160)>; }; &slot1_partition { reg = <0x00038000 DT_SIZE_K(160)>; }; &storage_partition { reg = <0x00060000 DT_SIZE_K(50)>; };

When I run the following MCUmgr command, I get back an NMP timeout, as seen below:

> mcumgr --conntype serial --connstring "dev=COM11,baud=115200" echo "test" Error: NMP timeout

So the mcumgr definitely realizes that the port is available (it would deny access otherwise), but it keeps getting timed out.

I'm pretty sure this is a config option error. I've tried changing the config options numerous times but nothing quite seems to do the trick. I'm also pretty sure I'm missing some config option somewhere which is crucial for this to work.

I've looked through about as many application notes and user manuals out there as I can. None of them seem to help for my particular case: DFU using Zephyr MCUboot on an LPC55Sxx chip running a Zephyr application.

Any help would is appreciated, though it may be best if someone tried it out on their board e.g. LPCXpresso55S69 and confirm they can carry out a UART DFU with any simple program.

Re: [LPC55S69] Zephyr MCUboot for Device Firmware Update Over UART Not Working with MCUmgr on LPC55S

Harry_Zhang — Wed, 05 Aug 2026 09:28:57 GMT

Hi @ZQ2

Since mcumgr echo is already returning NMP timeout, I think you can verify the MCUmgr UART communication before debugging the MCUboot DFU flow.

You can confirm the following:

flexcomm0 is the UART connected to COM11 on the LPCXpresso55S69 board.
The application is running normally (not staying in MCUboot serial recovery mode).
No console, shell, or log output is sharing the same UART used by MCUmgr.

As a quick validation, I would recommend starting from Zephyr's smp_svr sample

and verifying that the following command works first:

mcumgr --conntype serial --connstring "dev=COM11,baud=115200" echo "test"

Harry

Re: [LPC55S69] Zephyr MCUboot for Device Firmware Update Over UART Not Working with MCUmgr on LPC55S

ZQ2 — Wed, 05 Aug 2026 14:30:53 GMT

Hi @Harry_Zhang ,

Coincidentally, I was using Zephyr's smp_svr sample yesterday immediately after posting this question.

I get the same exact problem though.

I followed the Zephyr documentation for the sample at the following link.

I simply created a project for the sample and then built the code successfully, enabling the configs for the Raw UART (serial) smp_svr option from the docs using the following command, as instructed:

west build -p always -b lpcxpresso55s69/lpc55s69/cpu0 --sysbuild -- -DEXTRA_CONF_FILE="raw-serial.conf;fs.conf"

And then I flashed the code successfully.

Nonetheless:

C:\Users\Dev>mcumgr --conntype serial --connstring "dev=COM11,baud=115200" echo "test" Error: NMP timeout

I even tried changing the debugger probe from Link2 to JLink, after which the debug probe became attached to COM16. I also disabled any mass storage device functionality, just in case, using JLink commander.

Then I tried flashing and running:

> west flash -r jlink

but yet again:

C:\Users\Dev> mcumgr --conntype serial --connstring "dev=COM16,baud=115200" echo "test"
Error: NMP timeout

What could I possibly be missing? I assume it has something to do with the configs? If so, I wonder why the Zephyr official sample for smp_svr isn't compatible with the LPC55S69 and requires modification.

Re: [LPC55S69] Zephyr MCUboot for Device Firmware Update Over UART Not Working with MCUmgr on LPC55S

Harry_Zhang — Thu, 06 Aug 2026 09:08:05 GMT

Hi @ZQ2

I was able to reproduce and verify the setup on an LPCXpresso55S69 board.

1. The key point is that MCUmgr must be used together with MCUboot in this configuration. The application is linked to slot0 (not the flash base address), so building and flashing the smp_svr application alone will not work correctly. MCUboot is required to boot and hand over control to the application.

2. i add the overlay file lpcxpresso55s69_lpc55s69_cpu0.overlay in file /c/SDK/zephyrproject/zephyr/samples/subsys/mgmt/mcumgr/smp_svr/boards.

&boot_partition { reg = <0x00000000 DT_SIZE_K(64)>; }; &slot0_partition { reg = <0x00010000 DT_SIZE_K(160)>; }; &slot1_partition { reg = <0x00038000 DT_SIZE_K(160)>; }; &storage_partition { reg = <0x00060000 DT_SIZE_K(50)>; };

3. built the project using the following command:

west build -p always -b lpcxpresso55s69/lpc55s69/cpu0 --sysbuild samples/subsys/mgmt/mcumgr/smp_svr -- -DEXTRA_CONF_FILE="serial.conf" -DEXTRA_DTC_OVERLAY_FILE="C:/SDK/zephyrproject/zephyr/samples/subsys/mgmt/mcumgr/smp_svr/boards/lpcxpresso55s69_lpc55s69_cpu0.overlay" -Dmcuboot_EXTRA_DTC_OVERLAY_FILE="C:/SDK/zephyrproject/zephyr/samples/subsys/mgmt/mcumgr/smp_svr/boards/lpcxpresso55s69_lpc55s69_cpu0.overlay"

4. after built it. you can use command

grep -A20 -B5 "boot_partition" build/mcuboot/zephyr/zephyr.dts

5. and west flash

which confirms that the UART transport, SMP server, MCUmgr, and MCUboot integration are all working correctly.

Harry

Re: [LPC55S69] Zephyr MCUboot for Device Firmware Update Over UART Not Working with MCUmgr on LPC55S

ZQ2 — Thu, 06 Aug 2026 14:50:55 GMT

Hi @Harry_Zhang ,

Your solution does indeed work. In fact, I was able to strip down the command to merely

west build -p always -b lpcxpresso55s69/lpc55s69/cpu0 --sysbuild samples/subsys/mgmt/mcumgr/smp_svr -- -DEXTRA_CONF_FILE="serial.conf"

This also worked. Thank you a ton for replicating my problem, it's deeply appreciated.