Using an approach similar to what's in the ble_app_att_mtu_throughput example, my goal is to transfer data as fast as possible. (I.e. call sd_ble_gatts_hvx() on the same characteristic until I receive an NRF_ERROR_RESOURCES reply and then wait for the BLE_GATTS_EVT_HVN_TX_COMPLETE event before proceeding with notifications again.)
My questions are focused on the p_data member of the ble_gatts_hvx_params_t struct passed to sd_ble_gatts_hvx().
- Within that call, what gets added to the value notification queue?
- Does the value data being pointed to get copied into the queue, or does the pointer itself simply get saved in order to have the data obtained later when ready to be sent?
- Ultimately, can the same underlying, changing data buffer be used repeatedly, or does each call to sd_ble_gatts_hvx() need to have a unique buffer to back p_data?
For what it's worth, it appears that the couple of examples doing this are set up with a single buffer, suggesting the data is copied into the notification queue. But I would greatly appreciate the definitive answer on what's happening in the SoftDevice.
