nRF52840 with MCUBOOT over SMP using SPI Flash - Fails to boot

[zpm1066]

Hello,

I'm trying to use MCUBOOT with external flash on a nRF52840 board that has 4MB SPI flash. I'm using nRF Connect SDK v2.6.0.

I've verified that the SPI flash works fine using the "spi_flash" sample.

With CONFIG_BOOTLOADER_MCUBOOT=n, SMP with SPI flash runs fine. I'm able to connect to the "Zephyr" BLE device from nRF Connect for mobile.

However, with CONFIG_BOOTLOADER_MCUBOOT=y, the build is successful but the nRF52840 board fails to boot.

As the nRF52840 board (particle_xenon) has SPI flash instead of QSPI, I've set CONFIG_NCS_SAMPLE_MCUMGR_BT_OTA_DFU=n and added the required Kconfig dependencies.

Here is the prj.conf:

CONFIG_BT=y
CONFIG_BT_PERIPHERAL=y
CONFIG_MCUMGR=y
CONFIG_ZCBOR=y
CONFIG_CRC=y
CONFIG_MCUMGR_TRANSPORT_BT=y
CONFIG_MCUMGR_TRANSPORT_BT_CONN_PARAM_CONTROL=y
CONFIG_IMG_MANAGER=y
CONFIG_STREAM_FLASH=y
CONFIG_FLASH_MAP=y
CONFIG_MCUMGR_GRP_IMG=y
CONFIG_MCUMGR_GRP_OS=y
CONFIG_MCUMGR_GRP_OS_BOOTLOADER_INFO=y
CONFIG_MCUMGR_TRANSPORT_BT_REASSEMBLY=y
CONFIG_BASE64=y
CONFIG_MCUMGR_TRANSPORT_SHELL=y

CONFIG_NCS_SAMPLE_MCUMGR_BT_OTA_DFU=n
CONFIG_NCS_SAMPLE_MCUMGR_BT_OTA_DFU_SPEEDUP=y
CONFIG_BOOTLOADER_MCUBOOT=y

CONFIG_NORDIC_QSPI_NOR=n
CONFIG_FLASH=y
CONFIG_SPI=y
CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

CONFIG_LOG=y
CONFIG_PRINTK=y
CONFIG_CONSOLE=y
CONFIG_SERIAL=y

# Preferred SHELL options
CONFIG_SHELL=y
CONFIG_BOOT_BANNER=y
CONFIG_DATE_SHELL=y
CONFIG_POSIX_CLOCK=y
CONFIG_DEVICE_SHELL=n
CONFIG_INIT_STACKS=y
CONFIG_KERNEL_SHELL=y
CONFIG_SHELL_STATS=n

The board configuration "particle_xenon.conf" is set to use SPI flash:

CONFIG_FLASH=y
CONFIG_SPI=y
CONFIG_SPI_NOR=y

The board "particle_xenon.overlay" is configured to use the external SPI flash (&mx25l32 is defined in "particle_xenon.dts" board):

/ {
	chosen {
		nordic,pm-ext-flash = &mx25l32;
	};
};

For MCUBOOT, folder "child_image > mcuboot > boards" has the board configuration & overlay files as,

particle_xenon.conf:

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_IMAGE=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
### Use info log level by default
CONFIG_MCUBOOT_LOG_LEVEL_INF=y
### Decrease footprint by ~4 KB in comparison to CBPRINTF_COMPLETE=y
CONFIG_CBPRINTF_NANO=y
CONFIG_NRF_RTC_TIMER_USER_CHAN_COUNT=0
### Use the minimal C library to reduce flash usage
CONFIG_MINIMAL_LIBC=y

### Enable serial recovery
CONFIG_MCUBOOT_SERIAL=y
CONFIG_BOOT_SERIAL_CDC_ACM=y
CONFIG_BOOT_SERIAL_NO_APPLICATION=y
CONFIG_UART_CONSOLE=n

### Increase receive buffer to improve transfer speed in serial recovery mode
CONFIG_BOOT_MAX_LINE_INPUT_LEN=8192
CONFIG_BOOT_SERIAL_MAX_RECEIVE_SIZE=4096

### Enable SPI flash
CONFIG_NORDIC_QSPI_NOR=n
CONFIG_SPI=y
CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

### Partition size allocated to bootloader - can be reduced if logging is disabled
CONFIG_PM_PARTITION_SIZE_MCUBOOT=0x12000

particle_xenon.overlay:

/ {
	chosen {
		nordic,pm-ext-flash = &mx25l32;
	};

	aliases {
		mcuboot-button0 = &mode_button;
	};
};

MCUBOOT > zephyr > zephyr.dts does include the "nordic,pm-ext-flash". 
Here's a snippet from the file:

	model = "Particle Xenon";
	compatible = "particle,xenon", "particle,feather";
	chosen {
		zephyr,entropy = &cryptocell;
		zephyr,flash-controller = &flash_controller;
		zephyr,console = &uart0;
		zephyr,uart-mcumgr = &uart0;
		zephyr,shell-uart = &uart0;
		zephyr,sram = &sram0;
		zephyr,flash = &flash0;
		zephyr,code-partition = &slot0_partition;
		zephyr,ieee802154 = &ieee802154;
		nordic,pm-ext-flash = &mx25l32;
	};

What could be the reason for the application not running?

Am I missing some configuration or is part of it incorrect?  Thank you.

Regards,

Ravi

[zpm1066]

Hi Andreas,

Do you have any updates?

It may also be worth reaching out to your colleague Vidar Berg , as he provided the "mcuboot_external_flash" example

Regards,
Ravi

[zpm1066]

 AHaug 

Hi Andrea,

Do you have any update on a solution? Thanks.

Regards,
Ravi

[AHaug]

Hi Ravi

Apologies for the long response time, I've unfortunately been occupied with unforeseen things.

I spent this morning creating a sample showcasing BLE DFU where the secondary slot resides on external flash with SPI instead of QSPI. 

The sample is not optimized, and prj.conf has some configs that might not be necessary but I've tested and verified that the update goes through using the nRF Connect app following the brief steps mentioned in the samples READme

smp_ble_feat_spi.zip

This should hopefully be enough to showcase how to set this up

Kind regards,
Andreas

[zpm1066]

HI Andreas,

It's not an issue at all. I thought you must be either tied up or perhaps on vacation.

Thank you so much for taking the time to prepare an example. It's much appreciated.

I'll try your sample with a Particle Xenon (nRF52840) board that has external SPI flash. I'll have to change the "spi2" overlay to point to the board's flash. 


Regards,
Ravi

[AHaug]

Glad to hear that,

You may also investigate how the SPI flash is set up in the app.overlay as well as mcuboot.overlay and transfer that to the SPI flash JESD sample  from Zephyr. It should work given that you enter the right parameters.

As you see, the pins I've selected are based spi2's default pin setup but if you need different pins, you can also modify pin control for &spi2_default and _sleep by doing something like this 

 &pinctrl {
         spi2_default: spi2_default {
                 group1 {
                         psels = <NRF_PSEL(SPIM_SCK, 0, 29)>,
                                 <NRF_PSEL(SPIM_MISO, 0, 31)>,
                                 <NRF_PSEL(SPIM_MOSI, 0, 30)>;
                 };
         };
 
         spi2_sleep: spi2_sleep {
                 group1 {
                         psels = <NRF_PSEL(SPIM_SCK, 0, 29)>,
                                 <NRF_PSEL(SPIM_MISO, 0, 31)>,
                                 <NRF_PSEL(SPIM_MOSI, 0, 30)>;
                         low-power-enable;
                 };
         };
 };
 

Kind regards,
Andreas