Iphone can't connect ,if config #define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 50.

[gk117542]

I must set the MTU size to 23,if not ,iphone will disconnect the board after connected in 30seconds.

can some one help me ,and tell me why .

[Simonr]

Hi

Did you also remember to set the 

NRF_SDH_BLE_GAP_DATA_LENGTH to the MAX MTU SIZE + 4? This is required to allow for larger packets as well. The ble_app_hrs example has set an increased MTU size, so you can check that out for reference.

 

Best regards,

Simon

[gk117542]

sorry ,i can't find the definition on my sdk_config.h.

is that NRF_SDH_BLE_GAP_EVENT_LENGTH ?

// <o> NRF_SDH_BLE_CENTRAL_LINK_COUNT - Maximum number of central links.
#ifndef NRF_SDH_BLE_CENTRAL_LINK_COUNT
#define NRF_SDH_BLE_CENTRAL_LINK_COUNT 0
#endif

// <o> NRF_SDH_BLE_TOTAL_LINK_COUNT - Maximum number of total concurrent connections using the default configuration.
#ifndef NRF_SDH_BLE_TOTAL_LINK_COUNT
#define NRF_SDH_BLE_TOTAL_LINK_COUNT 1
#endif

// <o> NRF_SDH_BLE_GAP_EVENT_LENGTH - The time set aside for this connection on every connection interval in 1.25 ms units.
#ifndef NRF_SDH_BLE_GAP_EVENT_LENGTH
#define NRF_SDH_BLE_GAP_EVENT_LENGTH 3
#endif

// <o> NRF_SDH_BLE_GATT_MAX_MTU_SIZE - Static maximum MTU size.
#ifndef NRF_SDH_BLE_GATT_MAX_MTU_SIZE
#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 23//50//247
#endif

[gk117542]

Thank you for your reply,I will check the config file.

[Simonr]

If it is not defined at all you need to add it, as it is necessary that the data length is also set correctly as well to edit your MTU.

Best regards,

Simon