Writing to and reading from flash on nRF5340

RE: Writing to and reading from flash on nRF5340

Carl Richard — Tue, 13 Apr 2021 11:21:21 GMT

My pleasure! Glad I could help.

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Tue, 13 Apr 2021 11:00:35 GMT

Thank you Carl.

It is all making sense now. Thank you for your help.

Kind regards

Mohamed

RE: Writing to and reading from flash on nRF5340

Carl Richard — Tue, 13 Apr 2021 09:16:33 GMT

Hi again!

[quote user="Learner"]So, does this mean all 3 sectors were full? if this was the case then NVS should overwrite old information shouldn't it?[/quote]

So it seems. My understanding is that NVS won't overwrite information that's not a part of the NVS file system, thus avoiding disruption of any other potential flash operations. I suggest that you use the flash API to erase the affected memory if this situation occurs.

The sample should be configured correctly, but as you are using a custom board there may be some additional modifications required. Could you try with your original application and overlay again to see if the messages are printed correctly there?

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Tue, 13 Apr 2021 08:27:58 GMT

Good morning Carl,

[quote userid="68044" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/304413#304413"]If the board was used for something else earlier it's likely that there were some information left in the flash.[/quote]

So, does this mean all 3 sectors were full? if this was the case then NVS should overwrite old information shouldn't it?

Also, if this happens again, how can it be overcome from within the application?

[quote userid="68044" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/304413#304413"]Is printk over serial enabled in the application?[/quote]

I usually do this in an overlay file but this sample project did not have one. I would have expected since the sample uses printk then the environment in the sample project would have already been setup for it to work.

How can I enable printk over serial in the application?

Kind regards

Mohamed

RE: Writing to and reading from flash on nRF5340

Carl Richard — Tue, 13 Apr 2021 06:51:32 GMT

Hi again!

This means that the device weren't properly erased before programming. I guess this is caused by how Segger Embedded Studio erases and flashes the device. If the board was used for something else earlier it's likely that there were some information left in the flash.

The output you are seeing are (correct) log messages from the NVS subsystem. Is printk over serial enabled in the application?

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Mon, 12 Apr 2021 15:14:46 GMT

[quote userid="68044" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/304322#304322"]nrfjprog --recover[/quote]

With this command nvs_startup() is not returning an error and neither is nvs_init().

Why is this?

However, I am not seeing the output I expected to see. This is what I am seeing in the Debug Terminal.

Note, I have reduced the number of reboots to only 3.

[00:00:15.247,161] inf> fs_nvs: 3 Sectors of 4096 bytes
[00:00:15.247,161] inf> fs_nvs: alloc wra: 0, d08
[00:00:15.247,161] inf> fs_nvs: data wra: 0, 1fc

Any reason why I am not seeing the other print messages?

Kind regards

Mohamed

RE: Writing to and reading from flash on nRF5340

Carl Richard — Mon, 12 Apr 2021 14:14:25 GMT

Thanks. Have you tried to run "nrfjprog --recover" on the custom board before flashing the application to ensure that the flash is properly erased?

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Mon, 12 Apr 2021 13:54:54 GMT

I am programming all boards the same way namely, using Segger Embedded Studio and the nRF52833DK (or nRF5340PDK in case of nRF5340) connected to a USB port.

RE: Writing to and reading from flash on nRF5340

Carl Richard — Mon, 12 Apr 2021 12:15:17 GMT

Hi again!

How are you programming the custom board, versus the DK and the nRF5340 proprietary board? What interface, and what program are you using?

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Mon, 12 Apr 2021 12:08:19 GMT

Hi Carl,

[quote userid="68044" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/304218#304218"]What were your results from testing with the zephyr/samples/subsys/nvs sample?[/quote]

RE: Writing to and reading from flash on nRF5340

Carl Richard — Mon, 12 Apr 2021 09:44:50 GMT

Thank you for the information. I'm asking the developers to see if they have any input. What were your results from testing with the zephyr/samples/subsys/nvs sample?

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Fri, 09 Apr 2021 15:30:41 GMT

[quote userid="68044" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/304072#304072"]Can you confirm that the exact same code (except for the overlay) works with the nRF52833DK and the custom nRF5340 board?[/quote]

The exact same code including the same overlay works fine on the nRF52833DK.

Also the same code but with a different overlay file works fine on the nRF5340PDK and nRF5340 proprietary board.

RE: Writing to and reading from flash on nRF5340

Carl Richard — Fri, 09 Apr 2021 15:22:56 GMT

Hi again!

I agree that nothing in the overlay file should affect the flash, so that's probably not the culprit. Just wanted to make sure, but if it's not possible that's okay!

Can you confirm that the exact same code (except for the overlay) works with the nRF52833DK and the custom nRF5340 board? Could you test the standard zephyr/samples/subsys/nvs sample on the board and see if the behavior is similar?

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Fri, 09 Apr 2021 13:52:00 GMT

Hi Carl,

I cannot build without the overlay file. I don't think it has anything to do with it. I am attaching the overlay file just in case you may spot something.devzone.nordicsemi.com/.../nrf52833dk_5F00_nrf52833.overlay

[quote userid="68044" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/304019#304019"]What happens before you call flash_init?[/quote]

I call nvs_init() from within my function flash_init() that gets called from the main() function. Note, the failure occurs in nvs_startup() which is called from nvs_init().

static struct nvs_fs fs;

void main( void )

{

initialise();

...

}

void initialise( void )
{
// Setup a2d channels
adc_device_setup();
k_sleep( K_MSEC(1000) );

// Setup SPI devices
radio_spi_setup();

//spi_init();
k_sleep( K_MSEC(1000) );

// Configure LR1110
radio_gfsk_modem_config();
k_sleep( K_MSEC(1000) );

// Setup and Initialise timers
timer_init();

// Start timers
timer_start();

// Initialise Flash
flash_init();

}

void flash_init( void )
{
int32_t rc = 0;
struct flash_pages_info info;

/* define the nvs file system by settings with:
* sector_size equal to the pagesize,
* 3 sectors
* starting at FLASH_AREA_OFFSET(storage)
*/
fs.offset = FLASH_AREA_OFFSET( storage );

rc = flash_get_page_info_by_offs( device_get_binding( DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL ),
fs.offset, &info );
if ( rc )
{
printk( "Unable to get page info" );
}

fs.sector_size = info.size;
fs.sector_count = 3U;

rc = nvs_init( &fs, DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL );
if ( rc )
{
printk( "Flash Init failed\n" );
}

// Initialise static data flash area
flash_init_static();

// Initialise dynamic data flash area
flash_init_dynamic();

#if NDEBUG
/* Finally, lock the flash */
//TBD!!! flash_SetLockByte(0x80U);
#endif

}//flash_init()

RE: Writing to and reading from flash on nRF5340

Carl Richard — Fri, 09 Apr 2021 12:52:38 GMT

Hi again!

What happens before you call flash_init? If possible, please share your main function or main.c.

In addition, could you try to build without the overlay, so that we can rule out any potential issues there?

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Thu, 08 Apr 2021 08:25:14 GMT

Hi Carl,

[quote userid="68044" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/303648#303648"]Are you using a custom board definition for the proprietary nRF52833 board?[/quote]

As far as I can tell I am not, I am using the generic nRF52833DK board definition.

This is an extract of ...\build_nrf52833dk_nrf52833\zephyr\zephyr.dts,

/dts-v1/;

/ {
#address-cells = < 0x1 >;
#size-cells = < 0x1 >;
model = "Nordic nRF52833 DK NRF52833";
compatible = "nordic,nrf52833-dk-nrf52833";
chosen {
zephyr,entropy = &rng;
zephyr,flash-controller = &flash_controller;
zephyr,console = &uart0;
zephyr,shell-uart = &uart0;
zephyr,uart-mcumgr = &uart0;
zephyr,bt-mon-uart = &uart0;
zephyr,bt-c2h-uart = &uart0;
zephyr,sram = &sram0;
zephyr,flash = &flash0;
zephyr,code-partition = &slot0_partition;
};
aliases {

...

....

My overlay file is called nrf52833dk_nrf52833.overlay.

I am attaching the device tree file zephyr.dts and yaml file sample.yaml.

Note, This project was started by a colleague and I am adding the NVS flash functionality to it.

devzone.nordicsemi.com/.../5684.zephyr.dts

devzone.nordicsemi.com/.../sample.yaml

Kind regards

Mohamed

RE: Writing to and reading from flash on nRF5340

Carl Richard — Thu, 08 Apr 2021 07:24:32 GMT

Hi again!

You're getting the EDEADLK error, caused by all sectors being closed and unavailable to NVS. Are you using a custom board definition for the proprietary nRF52833 board?

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Wed, 07 Apr 2021 14:59:11 GMT

Thank you Carl.

I tried your suggestion but the problem is still there.

I tracked it down in the debugger and it seems the problem is occurring when nvs_startup() is called from nvs_init() it returns rc = -45 (0xffffffd3).

rc = nvs_startup(fs);
if (rc) {
return rc;
}

Digging even deeper in the API call tree, in nvs_startup(), I could see that the line of code closed_sectors++ gets executed three times so, closed_sectors = 3 although the SES debugger did not allow me to set a watch on this variable. I also set two breakpoints at the two lines highlighted in yellow. The first breakpoint was reached but not the second one. This confirms that closed_sectors == fs->sector_count hence the jump to end:. So, it looks like all 3 sectors are closed and therefore there is no sector available NVS can write to.

Why is this problem seen with nRF52833 (proprietary board) but not on nRF2833DK or on nRF5340 (another proprietary board)?

static int nvs_startup(struct nvs_fs *fs)
{

...

/* step through the sectors to find a open sector following
* a closed sector, this is where NVS can to write.
*/
for (i = 0; i < fs->sector_count; i++) {
addr = (i << ADDR_SECT_SHIFT) +
(uint16_t)(fs->sector_size - ate_size);
rc = nvs_flash_cmp_const(fs, addr, erase_value,
sizeof(struct nvs_ate));
if (rc) {
/* closed sector */
closed_sectors++;
nvs_sector_advance(fs, &addr);
rc = nvs_flash_cmp_const(fs, addr, erase_value,
sizeof(struct nvs_ate));
if (!rc) {
/* open sector */
break;
}
}
}
/* all sectors are closed, this is not a nvs fs */
if (closed_sectors == fs->sector_count) { // This breakpoint is reached
rc = -EDEADLK;
goto end;
}

if (i == fs->sector_count) { // This breakpoint is NOT reached
/* none of the sectors where closed, in most cases we can set
* the address to the first sector, except when there are only
* two sectors. Then we can only set it to the first sector if
* the last sector contains no ate's. So we check this first
*/

...

}

...

end:
k_mutex_unlock(&fs->nvs_lock);
return rc; // rc = -45

}//end of nvs_startup()

Also, in C:\Zypher\v1.5.0-rc1\zephyr\include\devicetree\zephyr.h I see where the macro DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL is defined but it is greyed out meaning it is disabled.

#if DT_NODE_HAS_PROP(DT_CHOSEN(zephyr_flash_controller), label)
#define DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL \
DT_LABEL(DT_CHOSEN(zephyr_flash_controller))
#endif

Thank you for your help.

Kind regards

Mohamed

RE: Writing to and reading from flash on nRF5340

Carl Richard — Wed, 07 Apr 2021 12:21:56 GMT

Hi again!

I think this might be caused by the flash controller already being bound to "flash_dev". NVS binds the flash controller as well and will likely fail if the device is already bound. Could you try to do as in the NVS sample, where they get the page info by referencing DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL directly? This ensures that it's released before nvs_init is called. See the code below.

int rc = 0,
struct flash_pages_info info;

/* define the nvs file system by settings with:
 *	sector_size equal to the pagesize,
 *	3 sectors
 *	starting at FLASH_AREA_OFFSET(storage)
 */
fs.offset = FLASH_AREA_OFFSET(storage);
rc = flash_get_page_info_by_offs(
	device_get_binding(DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL),
	fs.offset, &info);
if (rc) {
	printk("Unable to get page info");
}
fs.sector_size = info.size;
fs.sector_count = 3U;

rc = nvs_init(&fs, DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL);
if (rc) {
	printk("Flash Init failed\n");
}

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Wed, 07 Apr 2021 10:31:29 GMT

[quote userid="92434" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/303415#303415"]<error> fs_nvs: NVS not initialized[/quote]

This message is probably returned in response to subsequent NVS function calls. Although I am calling the function flash_get_page_count() after nvs_init() and it is returning page_count = 128 which looks like a valid value.

RE: Writing to and reading from flash on nRF5340

Learner — Wed, 07 Apr 2021 10:23:46 GMT

Hi Carl,

My NVS initialisation code looks like this and I am seeing the message in red below "Flash Init failed".

I think the returned value rc = 0xffffffd3

void flash_init( void )
{
uint32_t rc = 0;
struct flash_pages_info info;

/* define the nvs file system by settings with:
* sector_size equal to the pagesize,
* 3 sectors
* starting at FLASH_AREA_OFFSET(storage)
*/
fs.offset = FLASH_AREA_OFFSET( storage );
flash_dev = device_get_binding( DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL );
if ( flash_dev == NULL )
{
printk( "Flash device not bound!\n" );
return;
}
else
{
rc = flash_get_page_info_by_offs( flash_dev, fs.offset, &info );
if ( rc )
{
printk( "Unable to get page info" );
}
fs.sector_size = info.size;
fs.sector_count = 3U;

rc = nvs_init( &fs, DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL );
if ( rc )
{
printk( "Flash Init failed\n" );
}

size_t page_count = flash_get_page_count(flash_dev);
printk( "Flash contains %d pages of 4kB each\n", page_count );

...

Kind regards

Mohamed

RE: Writing to and reading from flash on nRF5340

Carl Richard — Wed, 07 Apr 2021 10:03:50 GMT

Hi!

That error should not be possible to get from nvs_init(...). Have you made sure that nvs_init is called before any other NVS functions? A complete log might help me identify the issue. I also suggest debugging the code to see where it fails.

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Wed, 07 Apr 2021 09:26:32 GMT

Hi Carl,

I've recently ported the code developed for the nRF5340 to the nRF52833 SoC and I am seeing this error when I call nvs_init(),

<error> fs_nvs: NVS not initialized

Any idea what could be causing this?

Kind regards

Mohamed

RE: Writing to and reading from flash on nRF5340

Carl Richard — Wed, 07 Apr 2021 09:09:07 GMT

Hi again, Mohamed!

Thank you for your patience and good to hear that NVS is more understandable now. I'm glad I could help! This is a part of the Zephyr RTOS so I think it's better if you open an issue for your suggestions in their GitHub issue tracker, as they likely can provide better help than me on the specifics of the NVS API.

Good luck on your project!

Best regards,
Carl Richard

RE: Writing to and reading from flash on nRF5340

Learner — Fri, 19 Mar 2021 15:24:36 GMT

Hi Carl,

[quote userid="68044" url="~/f/nordic-q-a/72772/writing-to-and-reading-from-flash-on-nrf5340/300919#300919"]

Elements are appended to a sector until storage space in the sector is exhausted. Then a new sector in the flash area is prepared for use (erased). Before erasing the sector it is checked that identifier - data pairs exist in the sectors in use, if not the id-data pair is copied.

From this it's clear that NVS is not wasteful when it comes to using flash, rather the other way around. The historical data will be overwritten over time, and the NVS subsystem will always ensure that the newest version id-data pair is kept.

[/quote]

I have read the documentation again and even after reading it many times I am just about beginning to understand better how NVS works. It is not very easy to read and digest how it all works for someone new to NVS. It would have been much better to complement the worded description with an illustrated example showing for example what happens when the current sector is full and writing to a new sector starts. Also, what happens when all sectors allocated are full.

I would appreciate a great deal if you could do that for me. 🤝😷

I am beginning to warm up to NVS much more than I did a day ago thanks to your explanation. I think I am going to stick with NVS and delay my move to flash API.

Thank you.

Kind regards

Mohamed