FOTA with external Flash.

Question

Hi Team, NCS v2.3.0 I need put the second slot FOTA on an external flash for nrf52840. 
 Is there any feasibility for use bluetooth dfu with SINGLE_APPLICATION_SLOT?

1. I added CONFIG_PM_EXTERNAL_FLASH_MCUBOOT_SECONDARY =y to prj.conf 2. I added to overlay: 
 
/ {
	chosen {
 nordic,pm-ext-flash = &mx25r64;
	};
};
 What else needs to be added to make it work? 
 
 Thank you.

Marte Myrvold · Accepted Answer

Hi,

You need to add the overlay with pm-ext-flash to both the application and MCUboot. If you have added this to an overlay file called something like <board_name>.overlay, then the structure should look like this:

project_dir
|__ src
|__ CMakeLists.txt
|__ prj.conf
|__ boards
    |__<board_name>.overlay
|__ child_image
    |__mcuboot
       |__ boards
           |__ <board_name>.overlay

Best regards,
Marte

Marte Myrvold · Answer

Hi Serhii, 
 I have checked this internally. There is no straightforward way to see that external flash is already in use. 
 If it is enough to check the generated build files, then you can look at the generated partition manager and devicetree files. In build/partitions.yml you can look for the partition that should be in external flash and look at the region. For example: 
 mcuboot_secondary:
 address: 0x0
 device: MX25R64
 end_address: 0xf4000
 region: external_flash
 size: 0xf4000 
 For devicetree you can look in build/zephyr/zephyr.dts and in build/mcuboot/zephyr/zephyr.dts, where pm-ext-flash should show up under 'chosen', and you can search for the external flash node itself to make sure the status is set to okay, similar to this: 
 / {
 chosen {
 ...
 nordic,pm-ext-flash = &mx25r64;
	};

...

qspi: qspi@40029000 {
 ...
 status = "okay";
 ...
 mx25r64: mx25r6435f@0 {
 ...
 };
}; 
 On the device itself you can for example check how much data is erased, since the slot is larger for external flash. 
 Best regards, Marte

FOTA with external Flash.

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