How do i get whole 31 byte BLE notification data at once?

[Abhijit Katariya]

In BLE notification i am getting 31 byte data but it comes in two packets 20 byte + 11 bytes continually.How do i get last 11 byte data which comes in 2nd packets after 2s time interval so that i can able to merge these two packet and make a array of 31byte at once?

[FormerMember]

As defined in the Bluetooth core specification v.4.2, vol 3, part F, chapter 3.4.7.1, the maximum amount of data per notification is 20 bytes.

Since the 2nd packet is transmitted 2 seconds later, I assume that your connection interval is 2 seconds. The S130/S132 v.2.0.1 supports up to six packets per connection interval, so it is possible to achieve much faster transfer than what you experience: When calling sd_ble_gatts_hvx(..) it will return NRF_SUCCESS or an error code. If it returned NRF_SUCCESS, the data will be put in a TX buffer and the application will receive the event BLE_EVT_TX_COMPLETE when the notification has been transmitted. There may not be one BLE_EVT_TX_COMPLETE event for each packet, but when a BLE_EVT_TX_COMPLETE event occurs, but the event contains the number of packets that was transmitted, see this message sequence chart.

For a fast transfer of data, you can therefore loop over sd_ble_gatts_hvx() as long as it doesn't return any error.