Maximum MTU size setting 512 not able to configure

[Paresh]

Hi 

In current development we will used the S112 soft device

SDK version 15.2.0

MCU is nrf52810

Try to update the below macro size to 512.

#ifndef NRF_SDH_BLE_GATT_MAX_MTU_SIZE
#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 512
#endif

Firmware gives run time error.

Debugging stop while check the firmware in debug mode.

regards from

Paresh Parekh

[Sigurd]

Hi!

You might need to allocate more RAM to the SoftDevice. See e.g. this page:  Adjustment of RAM and Flash memory and the video tutorial at this page https://infocenter.nordicsemi.com/topic/ug_gsg_ses/UG/gsg/debug.html

PS: If this is a new project, I recommend using nRF Connect SDK instead: https://www.nordicsemi.com/Products/Development-software/nrf-connect-sdk

[Paresh]

we had gone through the all relative documents. I would like to understand how we can further process for increasing the MTU size at what location we need to change? shifting the Soft driver address is understand but how it will effect the increase MTU size?

[Sigurd]

Did you get it to work with 512?

[Sigurd]

From the Bluetooth spec:

From BLUETOOTH CORE SPECIFICATION Version 5.2 | Vol 3, Part F page 1485:

"The maximum length of an attribute value shall be 512 octets."

[Paresh]

Linker file changes.

Error coded returns from below function.

we have tried memory changes as discribe with different values, still not able to set MTU size morethen 247.

we had set MTU size to just "NRF_SDH_BLE_GATT_MAX_MTU_SIZE = 260", still below functions give error.

Always "rx_char_spec_add()"  function returns with error code = 4.

Let's know value added feedback.

[Sigurd]

I'm not seeing the function rx_char_spec_add() in nRF5 DSK v15.2.0 , is it a function you have implemented? or maybe it's ported from an older SDK release? How does the rx_char_spec_add() function look like?