ble_gatts_evt_rw_authorize_request_t with offset

[Lodge]

Hi again, If I use BluetoothGATTSetCharacteristicValue and set wr_auth = 1 in the ble characteristics, I receive a BLE_GATTS_EVT_RW_AUTHORIZE_REQUEST event. I can also see the data and length from the requestEvent->request.write.data and requestEvent->request.write.len. My question is how does the requestEvent->request.write.offset value get updated? I want to send a lot of data to my device, and with a maximum packet size of 20 bytes, it would be nice to be able to determine the offset for each packet, so I can easily re-assemble the data at the receive end. Do I need to increase the attributeCharacteristicValue.max_len? Many thanks

[Hung Bui]

Hi Lodge,

The offset can be used for Queued/Long Write or Reliable Write

If your characteristic is less than 510 bytes long, you can use long write and let the stack handles the de-assembly and reassembly for you. If you having more than 510 bytes, you can think of define your own 2 bytes offset and mechanism to slit the packets and re-assembly them.

[Lodge]

Hi Hung Bui, Brilliant, thank you. In that case I can use the BluetoothGATTBeginReliableWrite function. The BLE_GATTS_EVT_RW_AUTHORIZE_REQUEST with a read request also has an offset field. If I wanted to read more than 20 bytes, how does this field get updated? Thanks again :-)