CONFIG_MCUMGR_SMP_UART disables CONFIG_UART_0_ASYNC

[Ryisen]

Hello everyone.

I'm using the nRF Connect SDK v1.6.1 (it's an old project) on a nRF5340. Our project is based on the central_bas sample.

I want to use MCUBoot to update the application in the field.

I added the necessary configs to the prj.conf of both our central_bas project as well as the MCUBoot project.

Now whenever I add "CONFIG_MCUMGR_SMP_UART=y" to the prj.conf of the central_bas project, it sets CONFIG_UART_0_ASYNC (everything applies to UART_1 as well) to false (or "n") and won't let me change it. Adding "CONFIG_UART_0_ASYNC=y" in the prj.conf does not change anything and I can't change it via "Configure nRF Connect SDK Project..." in Segger Embedded Studio as it is greyed out there.

Without "CONFIG_UART_0_ASYNC" our UART init fails during startup of our application.

What causes "CONFIG_MCUMGR_SMP_UART" to disable and lock "CONFIG_UART_0_ASYNC"?

Best regards,

Alex

prj.conf of central_bas:

#
# Copyright (c) 2019 Nordic Semiconductor ASA
#
# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
#
CONFIG_NCS_SAMPLES_DEFAULTS=y

CONFIG_BT=y
CONFIG_BT_DEBUG_LOG=y
CONFIG_BT_CENTRAL=y
CONFIG_BT_SMP=y
CONFIG_BT_GATT_CLIENT=y
CONFIG_BT_GATT_DM=y
# was before CONFIG_HEAP_MEM_POOL_SIZE=1024
CONFIG_HEAP_MEM_POOL_SIZE=2048
CONFIG_BT_BAS_CLIENT=y

CONFIG_BT_SCAN=y
CONFIG_BT_SCAN_FILTER_ENABLE=y
CONFIG_BT_SCAN_UUID_CNT=1
CONFIG_BT_PRIVACY=y

CONFIG_BT_SETTINGS=y
CONFIG_FLASH=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_FLASH_MAP=y
CONFIG_NVS=y
CONFIG_SETTINGS=y

CONFIG_DK_LIBRARY=y

### START added from peripheral_UART example ###
# Enable the UART driver
CONFIG_UART_ASYNC_API=y
CONFIG_NRFX_UARTE0=y
CONFIG_NRFX_UARTE1=y
CONFIG_SERIAL=y

CONFIG_GPIO=y

# Make sure printk is not printing to the UART console
CONFIG_CONSOLE=y
CONFIG_UART_CONSOLE=y

### END added from peripheral_UART example ###

# Enable nordic security backend and PSA APIs
CONFIG_MBEDTLS_LIBRARY_NRF_SECURITY=y
CONFIG_NORDIC_SECURITY_BACKEND=y
CONFIG_MBEDTLS_PSA_CRYPTO_C=y

CONFIG_MBEDTLS_ENABLE_HEAP=y
CONFIG_MBEDTLS_HEAP_SIZE=8192

### Added MCUBoot as first-stage bootloader ###
CONFIG_BOOTLOADER_MCUBOOT=y
CONFIG_MCUBOOT_IMAGE_VERSION="1.3.0+1"	# maj.min.rev+build
#CONFIG_BOOT_SIGNATURE_KEY_FILE="privMCUBoot.pem"
#CONFIG_BOOT_BUILD_DIRECT_XIP_VARIANT=y	# available in NCS v2.0.0 and above

# Enable mcumgr.
CONFIG_MCUMGR=y

# Enable most core commands.
CONFIG_MCUMGR_CMD_IMG_MGMT=y
CONFIG_MCUMGR_CMD_OS_MGMT=y

# Enable the serial mcumgr transport.
CONFIG_MCUMGR_SMP_UART=y
CONFIG_UART_MCUMGR_ON_DEV_NAME="UART_0"
#CONFIG_UART_0_ASYNC=y
#CONFIG_UART_1_ASYNC=y

# Some command handlers require a large stack. Important for mcumgr, would otherwise timeout
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=4096

### "UART_0" is the default value, other values like "UARTE_0" or "UART_1" prohibit output
#CONFIG_UART_CONSOLE_ON_DEV_NAME="UART_0"

### Fixed necessary project config ###
#CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=y
#CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y

#CONFIG_SOC_LFXO_CAP_EXTERNAL=y
#CONFIG_SOC_HFXO_CAP_EXTERNAL=y

#CONFIG_NRFX_CLOCK_LFXO_TWO_STAGE_ENABLED=n
#CONFIG_NRFX_CLOCK=y
### End of necessary project config ###

prj.conf of MCUBoot:

#CONFIG_CONSOLE_HANDLER=y
#CONFIG_SYSTEM_CLOCK_DISABLE=y
#CONFIG_SYS_POWER_MANAGEMENT=n

CONFIG_PM=n

CONFIG_MAIN_STACK_SIZE=10240
CONFIG_MBEDTLS_CFG_FILE="mcuboot-mbedtls-cfg.h"

CONFIG_BOOT_SWAP_SAVE_ENCTLV=n
CONFIG_BOOT_ENCRYPT_RSA=n
CONFIG_BOOT_ENCRYPT_EC256=n
CONFIG_BOOT_ENCRYPT_X25519=n

CONFIG_BOOT_UPGRADE_ONLY=n
CONFIG_BOOT_BOOTSTRAP=n

### mbedTLS has its own heap
# CONFIG_HEAP_MEM_POOL_SIZE is not set

### We never want Zephyr's copy of tinycrypt.  If tinycrypt is needed,
### MCUboot has its own copy in tree.
# CONFIG_TINYCRYPT is not set
# CONFIG_TINYCRYPT_ECC_DSA is not set
# CONFIG_TINYCRYPT_SHA256 is not set

CONFIG_FLASH=y
CONFIG_FPROTECT=y

### Various Zephyr boards enable features that we don't want.
# CONFIG_BT is not set
# CONFIG_BT_CTLR is not set
# CONFIG_I2C is not set

CONFIG_LOG=y
CONFIG_LOG_MODE_MINIMAL=y # former CONFIG_MODE_MINIMAL
### Ensure Zephyr logging changes don't use more resources
CONFIG_LOG_DEFAULT_LEVEL=0
### Decrease footprint by ~4 KB in comparison to CBPRINTF_COMPLETE=y
CONFIG_CBPRINTF_NANO=y

### Added for compatibility with our central_bas ###

CONFIG_BOOT_DIRECT_XIP=y
### Should be "y" per default, CONFIG_SERIAL=n disables the output from MCUBoot
#CONFIG_SERIAL=y
#CONFIG_UART_CONSOLE_ON_DEV_NAME="UART_0"

### Fixed necessary project config ###
#CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=y
#CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y

#CONFIG_SOC_LFXO_CAP_EXTERNAL=y
#CONFIG_SOC_HFXO_CAP_EXTERNAL=y

#CONFIG_NRFX_CLOCK_LFXO_TWO_STAGE_ENABLED=n
#CONFIG_NRFX_CLOCK=y
### End of necessary project config ###

Devicetree overlay of central_bas:

&uart0

{         tx-pin = < 0x1c >;         rx-pin = < 0x1a >;         rts-pin = < 0x1e >;         cts-pin = < 0x1f >; }

;

&uart1

{      status = "okay";      current-speed = < 0x1c200 >;     tx-pin = < 0x22 >;     rx-pin = < 0x0d >;  }

;

&i2c1

{     sda-pin = < 0x16 >;     scl-pin = < 0x17 >;     status = "disabled"; }

;

&pwm0

{     ch0-pin = < 0x10 >; }

;

&qspi

{    io-pins = < 0xf >;     status = "disabled"; }

;

&{/} {

  leds {
          compatible = "gpio-leds";
          led0: led_0

{                   gpios = < &gpio0 0x13 0x1 >;                   label = "Green LED 0";           }

;
          led1: led_1

{                   gpios = < &gpio0 0x15 0x1 >;                   label = "Green LED 1";           }

;
          led2: led_2

{                   gpios = < &gpio1 0x08 0x1 >;                   label = "Green LED 2";           }

;
          led3: led_3

{                   gpios = < &gpio1 0x06 0x1 >;                   label = "Green LED 3";           }

;
          led4: led_4

{                   gpios = < &gpio1 0x04 0x1 >;                   label = "Green LED 4";           }

;
  };

  aliases

{           led0 = &led0;           led1 = &led1;           led2 = &led2;           led3 = &led3;           led4 = &led4;           pwm-led0 = &pwm_led0;           sw0 = &button0;           sw1 = &button1;           sw2 = &button2;           sw3 = &button3;           bootloader-led0 = &led0;    }

;

};

Devicetree overlay of MCUBoot:

/ {
	chosen {
		zephyr,code-partition = &boot_partition;
	};
};

&uart0

{         tx-pin = < 0x1c >;         rx-pin = < 0x1a >;         rts-pin = < 0x1e >;         cts-pin = < 0x1f >; }

;

&uart1

{      status = "okay";      current-speed = < 0x1c200 >;     tx-pin = < 0x22 >;     rx-pin = < 0x0d >;  }

;

&i2c1

{     sda-pin = < 0x16 >;     scl-pin = < 0x17 >;     status = "disabled"; }

;

&pwm0

{     ch0-pin = < 0x10 >; }

;

&qspi

{    io-pins = < 0xf >;     status = "disabled"; }

;

&{/} {

  leds {
          compatible = "gpio-leds";
          led0: led_0

{                   gpios = < &gpio0 0x13 0x1 >;                   label = "Green LED 0";           }

;
          led1: led_1

{                   gpios = < &gpio0 0x15 0x1 >;                   label = "Green LED 1";           }

;
          led2: led_2

{                   gpios = < &gpio1 0x08 0x1 >;                   label = "Green LED 2";           }

;
          led3: led_3

{                   gpios = < &gpio1 0x06 0x1 >;                   label = "Green LED 3";           }

;
          led4: led_4

{                   gpios = < &gpio1 0x04 0x1 >;                   label = "Green LED 4";           }

;
  };

  aliases

{           led0 = &led0;           led1 = &led1;           led2 = &led2;           led3 = &led3;           led4 = &led4;           pwm-led0 = &pwm_led0;           sw0 = &button0;           sw1 = &button1;           sw2 = &button2;           sw3 = &button3;           bootloader-led0 = &led0;    }

;

};

[Marte Myrvold]

Hi,

The mcumgr UART driver is interrupt driven. You can see this in the Kconfig documentation: CONFIG_MCUMGR_SMP_UART selects CONFIG_UART_MCUMGR, which selects CONFIG_UART_INTERRUPT_DRIVEN. If you look at CONFIG_UART_0_ASYNC you see that this has the dependency that CONFIG_UART_INTERRUPT_DRIVEN is not selected. This means that in order to use mcumgr SMP UART you cannot use asynchronous UART in your application, but must use interrupt driven UART instead.

Depending on your use case another option can be to use serial recovery instead of SMP. A colleague of mine has made some minimal examples for serial recovery, both over UART and USB (cdc_acm) that you can find here: https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples/serial_recovery. These are based on v2 of nRF Connect SDK, so they will not be directly compatible with v1.6.1, but they can help with how to get started with serial recovery.

Best regards,

Marte

[Ryisen]

Thank you for your clarification. I will have a look at those examples.

Best regards,

Alex