Insufficient RAM allocated for the SoftDevice in nrf_sdh_ble_enable

[Daniel Reisfeld]

Hi,

I've defined:

#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 120 (in sdk_config.h)

I get "Insufficient RAM allocated for the SoftDevice" in nrf_sdh_ble_enable

nrf_sdh_ble_enable parameter *p_app_ram_start == 0

I'm using the last SDK version (15.0) on nRF52840

Please advise.

Thanks!,

Daniel

[Martin Lesund]

Hi Daniel,

When you change your MTU size you should also change the RAM allocation since the RAM usage for the stack will depend on certain things, like the GATT table size, MTU and TX-buffering settings, and similar.

If you modify NRF_SDH_BLE_GATT_MAX_MTU_SIZE you should adjust RAM start and RAM size for your project. If you have some log output maybe it is reporting you some warnings like this:

nrf_sdh_ble: RAM start should be adjusted to 0x20002968. nrf_sdh_ble: RAM size should be adjusted to 0xD698. nrf_sdh_ble: sd_ble_enable() returned NRF_ERROR_NO_MEM. app: Fatal

If you are using, for example, Keil MDK it can be adjusted at Options for target -> Target (similar thread)

[Daniel Reisfeld]

Hi,

Are those numbers (RAM start and size) apply if the MTU size is further increased?

I'm using Segger embedded studio. Can you tell me where I need to change these parameters?

Thanks,

Daniel

[Martin Lesund]

Hi Daniel, 

• You should change the RAM allocation if you change the MTU size. You will get a log output for the recommended RAM allocation.
• Please check out this Youtube tutorial on how this is done

 

[Daniel Reisfeld]

Martin,

Do you refer to the following lines in the flash_placement.xml file?:

<MemorySegment name="RAM" start="$(RAM_PH_START)" size="$(RAM_PH_SIZE)">
<ProgramSection load="no" name=".reserved_ram" start="$(RAM_PH_START)" size="$(RAM_START)-$(RAM_PH_START)" />
<ProgramSection alignment="0x100" load="No" name=".vectors_ram" start="$(RAM_START)" address_symbol="__app_ram_start__"/>

If so, I still don't understand how to change it. If not, can you kindly elaborate where I need to change.

Thanks,

Daniel