Delivery order of BLE indications/notifications

RE: Delivery order of BLE indications/notifications

run_ar — Tue, 23 Feb 2021 10:25:01 GMT

What peer/ central device are you testing with? Can you capture a sniffer log of this procedure to check the on air sequence?

RE: Delivery order of BLE indications/notifications

Campbell Young — Mon, 22 Feb 2021 22:48:45 GMT

Nah, I queue all notifications (about 200) then after the last one is queued, I queue the indication. When the remote end gets the indication, it will check if all the expected notifications were received. However, because the indication is coming before the notifications, it thinks packets are missing. Those missing packets arrive after the indication, so they do eventually get sent. For the purpose of this issue, there is only a single cycle happening. e.g. queue all notifications, queue indication, then stop.

RE: Delivery order of BLE indications/notifications

run_ar — Mon, 22 Feb 2021 11:07:29 GMT

Are you doing this in cycles? I.e. you send 30 notifications then you send a indications, then repeat? If you do, you most likely get the BLE_GATTS_EVT_HVC from the first 30 notification in the next sequence of notifications. I.e you will be able to send notifications even if you have a pending indication. So unless you wait for the BLE_GATTS_EVT_HVC before you start sending the next sequence of notification I would expect the BLE_GATTS_EVT_HVC to come somewhere in the next notification sequence, as it takes some time for the application layer to process indications.

RE: Delivery order of BLE indications/notifications

Campbell Young — Sat, 20 Feb 2021 23:58:37 GMT

I am queueing packets via sd_ble_gatts_hvx whose size is set by hvn_tx_queue_size in a call to sd_ble_cfg_set. The indications are queued in an application queue, although for the purpose of this issue it is only one element long, and so is queued directly via sd_ble_gatts_hvx after the notifications have been queued via the same method.

I queue notifications until sd_ble_gatts_hvx returns an error. Once I get BLE_GATTS_EVT_HVN_TX_COMPLETE I try queueing again until all notifications are queued. Once they're queued, I then queue the indication.

Hope that makes sense!

Code for configuring queue size:

ble_cfg_t ble_cfg;
memset(&ble_cfg, 0x00, sizeof(ble_cfg));
ble_cfg.conn_cfg.conn_cfg_tag = APP_BLE_CONN_CFG_TAG;
ble_cfg.conn_cfg.params.gatts_conn_cfg.hvn_tx_queue_size = CFG_BLE_HVX_QUEUE_LEN;
err_code = sd_ble_cfg_set(BLE_CONN_CFG_GATTS, &ble_cfg, ram_start);

RE: Delivery order of BLE indications/notifications

run_ar — Fri, 19 Feb 2021 12:11:05 GMT

Hi,

What queue are you placing the packets in? I do not think it is possible to configure the SD with more than 7 TX buffers per connection. Are you sure you are not placing the packets in different additional buffers so the order it is placed in the actual tx buffers are changed?