MTU size of nRF52832 as central

[Youngjun]

Hi, I'm testing nRF52832 central data rate. My SDK version is 14.0.0 and softdevice is 5.0.0. I want to send 200byte from nRF52832 peripheral to nRF52832 central in one packet. And, central device will connect to PC. For this test, i was change central's MTU size to 250, i got "sd_ble_enable() returned NRF_ERROR_NO_MEM" message. How do i change cetral mtu size?

[Petter Myhre]

You need to increase the amount of RAM reserved for the SoftDevice, i.e. you need to increase the RAM starting address of the application.

[Intelesano Jose]

Hello Petter for increase Ram reserved i should chance here #define BLE_GATT_ATT_MTU_DEFAULT          23?? If not you tell me how to chance de RAM starting address please?

[Petter Myhre]

No, you need to increase the RAM starting address of your application, this is done in your project settings. For Keil:

Options for Target -> Target -> IRAM1

[Baruch]

This is the answering of the subject "where" but not "how". If one wants to go from the default size 23 bytes to let's say 123 bytes then the starting address shall move by 100 bytes? Is it all the changes or some defines needed to be updated as well?

Thanks.

[Petter Myhre]

Have a look at nrf_sdh_ble_enable(). It should tell you what RAM start and size should be set to.