Soft device 7.2.0 Flash and RAM configuration

[DaveC]

Hi

I am updating from Softdevice 6.1.1 to 7.2.0 and have issues with nrf_sdh_ble_enable(..), My setup is:

• NRF52840
• SDK 17.0.2
• SoftDevice 7.2.0
• Running FreeRtos
• GCC compiler using linker script

What I did:

• I updated the linker script as below

MEMORY
{
FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0xD9000
RAM (rwx) : ORIGIN = 0x200016FC, LENGTH = 0x38000
}

• The Flash values I'm sure are OK for Soft Device 7.2.0?
• The RAM Origin was obtained by booting the device and calling nrf_sdh_ble_default_cfg_set
• The RAM size is 256K - the value in the soft device release note (5.6K) plus a bit more

What is happening

• I boot the device but get an error when I run the following sequence:

uint32_t ram_start = 0;
err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start); << Returns NRF_SUCCESS (0)

//Note this returns 0=Success
//NOTE! ram_start = 536888912

nrf_sdh_ble_enable(&ram_start); << RETURNS NRF_ERROR_NO_MEM (4)

Any Ideas? 

[DaveC]

Update, Sorry I just realized my Linker script was incorrect, should have been 

MEMORY
{
FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0xD9000
RAM (rwx) : ORIGIN = 0x20004650, LENGTH = 0x38000
}

[DaveC]

So with this Configuration I get an error when calling nrf_sdh_enable(..) as above:

MEMORY
{
FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0xD9000
RAM (rwx) : ORIGIN = 0x200016FC, LENGTH = 0x38000
}

And with this configuration Free Rtos generates a vApplicationStackOverflowHook() error

MEMORY
{
FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0xD9000
RAM (rwx) : ORIGIN = 0x20004650, LENGTH = 0x38000
}

Any Ideas?

[Vidar Berg]

Hello,

Sorry for the delayed response. The linker script looks to be correct now, but I'm not sure why the vApplicationStackOverflowHook() becomes invoked. Have you tried to increases the stack sizes in all of your Freertos tasks? I would also try to increase the stack for the Softdevice task (NRF_BLE_FREERTOS_SDH_TASK_STACK). It's only 256 bytes by default, which may be a bit low depending on the application.

[DaveC]

Thanks for the reply.  I'm updating from an older sdk/soft device to 7.2.0.  The freertos settings have not changed for the application.  They work fine when I use the same ap/freertos with the old sdk/soft device (6.1.1)

[Vidar Berg]

Maybe some of the updated modules (SDK or Freertos) has lead to a slight increase in stack usage?  As far as I can tell, the vApplicationStackOverflowHook() function should not get called unless you actaully have a stack overflow in one of the threads.

[DaveC]

We think we found the issue.  It seems that when using SDK 17.0.2 (Soft Device 7.2.0) we have to increase the value of #define:

• #define NRF_BLE_FREERTOS_SDH_TASK_STACK 256 in file nrf_sdh_freertos.c

This is a hard coded define within the Nordic SDK.  We have provisionally double it to 512 and the FreeRtos stack overflow exception is no longer thrown (a smaller value could also work)

Q1) As this is a hard coded value within the SDK should it not just work "out of the box"

Q2) If the value has to be modified per application should it not be part of the Config setup?

[Vidar Berg]

Thanks for the update. Yes, this define should have been part of the config setup, and not a hardcoded setting in the source file as the required stack size is application depentent. This has been reported internally.