Flash erase/write problems

RE: Flash erase/write problems

EricDelangis — Mon, 27 Apr 2020 13:21:00 GMT

Hi Susheel,

That explains a lot. I thought that I wasn't in an interrupt while running my main service function. Can you direct me to some documentation that explains the underlying design philosophy to this system? Does it use a Linux kernel? How do the SDs operate and interact with user code? Who does per review?

Thanks

RE: Flash erase/write problems

Susheel Nuguru — Mon, 27 Apr 2020 12:21:23 GMT

There are tons of things that are wrong in your program. And I strongly suggest you to get your code peer reviewed. I have not done any detailed code review but spending 5 minutes with main.c file I see that you call ble_nus_c_evt_handler-> ble_handle_message->convert_temperature_values->update_flash_info->erase_flash->While(never_ending_loop)

Basically doing a flash activity inside the BLE event handler and waiting for an event while in interrupt context is not a good idea at all. You need to probably use app_scheduler to push all this activity you are doing for converting temperature values into thread context instead of doing so much oeprations inside an interrupt context.

RE: Flash erase/write problems

EricDelangis — Fri, 24 Apr 2020 14:20:42 GMT

Hi Susheel,

I do not like hard delays either but I've been unable to get anything else working properly. Though, I've got my doubts about hard delays working properly without excessively long delays that will affect the SD.

I've attached my code./cfs-file/__key/communityserver-discussions-components-files/4/2043._2100_PerfShwrValve.zip

You can unzip in examples directory.

RE: Flash erase/write problems

Susheel Nuguru — Fri, 24 Apr 2020 11:00:21 GMT

Can you please upload your whole project, so that I can look at the contexts properly to be able to give any suggestions to you.

[quote user="EricDelangis"]Do you have example code that uses hard delays (nrf_delay_xx)?[/quote]

We normally use a timer asynchronous delay instead of of busy delays when we are using softdevice, since most of the processing is done in the interrupt handlers with BLe activity. It does not mean that you can not use a busy delay nrf_delay_ms when executing in Thread context.

RE: Flash erase/write problems

EricDelangis — Tue, 21 Apr 2020 15:27:34 GMT

So, how do I get around this so the flash erase and writes are reliable? Do you have example code that uses hard delays (nrf_delay_xx)? I can live with the delays as long as the SD 132 can.

RE: Flash erase/write problems

Susheel Nuguru — Tue, 21 Apr 2020 06:44:22 GMT

[quote user="EricDelangis"]Are you sure that I don't have any coding errors that are causing the problems? [/quote]

Hi Eric,

I cannot answer that since I do no know the contexts of all the calls happening. But if you are calling erase_flash_page and write_flash_page from Thread context, then I do not see anything in your code that blocks the SD events indefinitely.

RE: Flash erase/write problems

EricDelangis — Sun, 19 Apr 2020 16:59:32 GMT

Hi Susheel,

Are you sure that I don't have any coding errors that are causing the problems? I am not using interrupts, only timers and I don't have any while() statements in my timer handling routines. Am I correctly processing the SD event?

RE: Flash erase/write problems

Susheel Nuguru — Sun, 19 Apr 2020 10:49:35 GMT

They should work, your application should have received SD events unless your application has while() statement in an interrupt context that blocks the SD_EVT_IRQHandler

RE: Flash erase/write problems

EricDelangis — Fri, 17 Apr 2020 13:03:35 GMT

I put this code in because the SD events functions were not working. I left them in because they don't affect the writing anyway. Even so, the SD events aren't working so this code should allow enough time for a write to work. However, it doesn't work reliably anyway. I will remove this code once the SD events are confirmed to be working.

Why aren't my SD events working?

RE: Flash erase/write problems

Susheel Nuguru — Fri, 17 Apr 2020 08:02:23 GMT

Why do you have the below?

    while(!flash_operation_completed)
    {
//    nrf_delay_ms(100);     // 85ms minimum flash time to finish erase cycle
//    sd_app_evt_wait();
    flash_operation_completed = true;
    }

If the flash oepration is complete, you will get the event from the SD, why do you force it to be completed within 100ms anyways. Then there would be no point in having the events.

RE: Flash erase/write problems

EricDelangis — Thu, 16 Apr 2020 19:41:27 GMT

Hi Susheel,

I still can't get the flash writes working reliably. I found this thread https://devzone.nordicsemi.com/f/nordic-q-a/44306/issue-with-nrf_sdh_soc_observer that solved the same problem as I am having but I haven't been able to get my code to work. Here's what I've got:

/****************** Erase Flash ***************************/
void erase_flash_page(void)
{
    NRF_LOG_INFO("Erasing Flash...");
    uint32_t evt = 0;
retry_flash:
    flash_operation_completed = false;
    sd_flash_page_erase(pg_num);
/*   
    while(!flash_operation_completed)
    {
      sd_evt_get (&evt);
      if (evt == NRF_EVT_FLASH_OPERATION_SUCCESS || evt == NRF_EVT_FLASH_OPERATION_ERROR)
      {
        flash_operation_completed = true;
        goto resume_flash_operations;
      }
      else 
      {
        start_flash_timer();
        goto retry_flash;
      }
    }
*/
    while(!flash_operation_completed)
    {
//    nrf_delay_ms(100);     // 85ms minimum flash time to finish erase cycle
//    sd_app_evt_wait();
    flash_operation_completed = true;
    }

resume_flash_operations:
    return (12345);
}

/****************** Write Flash ***************************/
void write_flash_page(void)
{
    NRF_LOG_INFO("Writing Flash...");
    uint8_t block_size = sizeof(write_flash_block);
    ret_code_t err_code;
    flash_operation_completed = false;
    err_code = sd_flash_write((uint32_t*)flash_addr, (uint32_t*)&write_flash_block, block_size);

    if (err_code != NRF_SUCCESS)
    {
       NRF_LOG_INFO("Error writing to flash, err_code = \"%x\" .", err_code);
        if (err_code == NRF_ERROR_INVALID_LENGTH) while (1);
        if (err_code == NRF_ERROR_INVALID_ADDR) while (1);
        if (err_code == NRF_ERROR_BUSY) while (1);
        if (err_code == NRF_ERROR_FORBIDDEN) while (1);
    }

    while(!flash_operation_completed)
    {
    sd_app_evt_wait();
    nrf_delay_ms(2);     // <1 ms minimum flash time to finish write cycle
    flash_operation_completed = true;
    }
}

Here's my nrf_sdh_soc_observer and handler stuff: (Note: I found a thread that talked about enabling NRF_SDH_SOC_ENABLE, it is enabled in the sdk_config.h file, but I can't find any function in the Nordic directories and I get an error when I try to instantiate it in lines 42-45.)

  // flash storage handler
static void soc_evt_handler(uint32_t evt_id, void * p_context)
{
    switch (evt_id)
    {
        case NRF_EVT_FLASH_OPERATION_SUCCESS:
        // fall through 
        case NRF_EVT_FLASH_OPERATION_ERROR:

            if (flash_operation_completed)
            {
                flash_operation_completed = false;
            }
            break;

        default:
            // No implementation needed.
              flash_operation_completed = true;
            break;
    }
}
/* ******************************** End *********************************/

static void ble_stack_init(void) {
  ret_code_t err_code;
  uint32_t   ram_start = 0;

  err_code = nrf_sdh_enable_request();
  APP_ERROR_CHECK(err_code);

  // Configure the BLE stack using the default settings.
  // Fetch the start address of the application RAM.
//  uint32_t ram_start = 0;
  err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
  APP_ERROR_CHECK(err_code);

  // Enable BLE stack.
  err_code = nrf_sdh_ble_enable(&ram_start);
  APP_ERROR_CHECK(err_code);

 /*************************** Added by Eric ***********************/
 // Enable SOC.
//  err_code = nrf_sdh_soc_enable();
//  err_code = NRF_SDH_SOC_ENABLE();
//  APP_ERROR_CHECK(err_code);
/* ******************************** End *********************************/

  // Register a handler for BLE events.
  NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);

/*************************** Added by Eric ***********************/
  NRF_SDH_SOC_OBSERVER(m_soc_observer, APP_SOC_OBSERVER_PRIO, soc_evt_handler, NULL);
/*
  // Register with the SoftDevice handler module for BLE events.
  err_code = softdevice_sys_evt_handler_set(sys_evt_dispatch);
  APP_ERROR_CHECK(err_code);

    /* Request Softdevice to turn on Crystal oscillator to test if SoC events are
       forwarded to the application. _SOC_ observers should get notified of the
       NRF_EVT_HFCLKSTARTED event after this call. */
    err_code = sd_clock_hfclk_request();
    APP_ERROR_CHECK(err_code);
/* ******************************** End *********************************/
}

RE: Flash erase/write problems

EricDelangis — Thu, 16 Apr 2020 17:51:21 GMT

I am using ble_central without modifications. However, I do include ble_uart_central, pwm, saadc and flash functions. A search of the code has NO references to FDS so I don't know how it saves the keys. And as I said, disabling FDS in sdk_config.h did not generate any errors. The big question is how do I write to flash reliably since it doesn't return either success for failure messages? With hard delays, i.e. nrf_delay_ms(100), for a flash page erase, and nrf_delay_ms(2) for a flash page write, it sometimes works.

RE: Flash erase/write problems

Susheel Nuguru — Thu, 16 Apr 2020 13:56:43 GMT

[quote user="EricDelangis"]I'm not sure when you say "You need to differentiate your logic between the completed flag and successful flag." The problem is that neither flag is getting set! So differentiating at this point will make no difference. I'll try the soc_evt_handler to see how that works[/quote]

It means that you need to set "flash_operation_completed = true;" in both NRF_EVT_FLASH_OPERATION_SUCCESS and also in the case NRF_EVT_FLASH_OPERATION_ERROR. This is because your application is depending on the flash operation to complete to exit from the wait loop and if flash operation returns NRF_EVT_FLASH_OPERATION_ERROR, then your application will loop for ever even though there is no ongoing flash operations.

[quote user="EricDelangis"]Finally, are you saying that the sd_flash_write/erase functions will work with the ble_central apps and that I don't need to use FDS? I turned OFF (disabled) FDS in the sdk_config.h file and didn't get any compile errors so I don't think that FDS is used for saving ble keys as previously stated by Turbo J. Is that correct?[/quote]

If you are using peer_manager library for storing BLE keys, it does use FDS. I used them in my reply since it seemed that you are using them already based on your original question.

RE: Flash erase/write problems

Susheel Nuguru — Thu, 16 Apr 2020 13:54:15 GMT

you should add it in the ble_stack_init at the same level where you plugin your ble_evt_handler for your application as BLE events observer.

RE: Flash erase/write problems

EricDelangis — Thu, 16 Apr 2020 13:47:39 GMT

Hi Susheel,

How does the code you reference work? I can't seem to get the NRF_SDH_SOC_OBSERVER(m_soc_observer, APP_SOC_OBSERVER_PRIO, soc_evt_handler, NULL); to run.

RE: Flash erase/write problems

EricDelangis — Tue, 14 Apr 2020 13:59:31 GMT

Hi Susheel,

I am calling my flash routines from my main(void) functions. NOT INTERRUPTS. You said "Then it means that which ever is not the flash event will be ignored completely by your whole application since sd_evt_get pull the event from the buffer and hence the rest of the application will not get any other event while you are calling sd_evt_get (&evt); and ignoring the non flash events." I had that same thought when working with the sd_evt_get (&evt) function. Thanks for confirming that.

I'm not sure when you say "You need to differentiate your logic between the completed flag and successful flag." The problem is that neither flag is getting set! So differentiating at this point will make no difference. I'll try the soc_evt_handler to see how that works.

Finally, are you saying that the sd_flash_write/erase functions will work with the ble_central apps and that I don't need to use FDS? I turned OFF (disabled) FDS in the sdk_config.h file and didn't get any compile errors so I don't think that FDS is used for saving ble keys as previously stated by Turbo J. Is that correct?

RE: Flash erase/write problems

Susheel Nuguru — Tue, 14 Apr 2020 11:02:50 GMT

[quote user=""]This code executes but it does not check for the flash erase function to complete. In debugging the problem, I found that the write function sd_flash_write() was erroring out on err_code == NRF_ERROR_BUSY. So I figured the erase function required more time to complete[/quote]

Are you calling your write_flash_page from main Thread context or an intterrupt context? Calling this interrupt context si not a good idea as you seem to be busy waiting on the flash complete flag

sd_evt_get (&evt);

So you are using sd_evt_get (&evt); in your code to know if the flash event is complete or not. Then it means that which ever is not the flash event will be ignored completely by your whole application since sd_evt_get pull the event from the buffer and hence the rest of the application will not get any other event while you are calling sd_evt_get (&evt); and ignoring the non flash events.

using NRF_EVT_FLASH_OPERATION_SUCCESS/NRF_EVT_FLASH_OPERATION_ERROR both tells that the flash operation has completed and NRF_EVT_FLASH_OPERATION_SUCCESS only tells that the flash operation has been successful. You need to differentiate your logic between the completed flag and successful flag.

in the file examples\ble_central\ble_app_gatts\main.c you can see that you can plug in a soc_evt_handler as an observer to soc events, you need to do that instead of creating your own callback function

NRF_SDH_SOC_OBSERVER(m_soc_observer, APP_SOC_OBSERVER_PRIO, soc_evt_handler, NULL);

RE: Flash erase/write problems

EricDelangis — Mon, 13 Apr 2020 22:08:19 GMT

I was previously told (by another Nordic tech support person) to use the sd_flash_page_erase() / write functions. The problem is that I only need to store a single structure in flash and the FDS code carries a HUGE overhead. Do you have a scaled down example that uses FDS but only deals with storing and reading a few system variables? I don't need any kind of record processing support.

RE: Flash erase/write problems

Turbo J — Mon, 13 Apr 2020 07:04:28 GMT

[quote userid="82465" url="~/f/nordic-q-a/60113/flash-erase-write-problems"] I implemented the sd_flash_page_erase() function as follows:[/quote]

That won't do.

The ble_* examples already use FDS in order to store BLE data (device keys) in Flash. I strongly recommend using FDS for your application, too.