how to reduce ble_nus_string_send cost?

RE: how to reduce ble_nus_string_send cost?

Stayhungry — Thu, 09 Nov 2017 14:40:53 GMT

Thank you very much. Your answer is very useful

RE: how to reduce ble_nus_string_send cost?

Hung Bui — Thu, 09 Nov 2017 14:35:33 GMT

Yes, you should set the TX_QUEUE_SIZE to 6 or higher.

When you enable connection event extension, it's not very important which event length you set (but you still need to set the queue size big enough). The softdevice will try to send as much as possible until the buffer is empty or when the connection event is finish.

Most important, you need to get the connection interval to as low as possible, 7.5ms is the lowest.

I would suggest you to have a look at our ble_app_att_mtu_throughput in the SDK.

RE: how to reduce ble_nus_string_send cost?

Stayhungry — Thu, 09 Nov 2017 10:15:03 GMT

Thanks,Hung Bui.

I do not know my understanding right, in the ble_gatts.h file BLE_GATTS_HVN_TX_QUEUE_SIZE_DUFAULT this macro definition, if I want to send 6 LL packet in a conneviton event, as long as this is set to 6, and then continue to call sd_ble_gatts_hvx until NRF_ERROR_RESOURCES return, and then Waiting for BLE_GATTS_EVT_HVN_TX_COMPLETE on it, if set to 1, can only send one LL packet.

Another question, if I understand correctly, when I enable the Connetion event extendsion, does this macro definition make sense?

RE: how to reduce ble_nus_string_send cost?

Hung Bui — Wed, 08 Nov 2017 14:23:40 GMT

Hi,

Have look here: devzone.nordicsemi.com/.../