How to configure multiple notifications per connection event

RE: How to configure multiple notifications per connection event

CheMax — Tue, 25 Jun 2019 08:55:59 GMT

Hello,

Sorry, but i don't understad why need change APP_BLE_CONN_CFG_TAG (default value 1 in main example) to BLE_CONN_CFG_GATTS. What improvement does it give? Where can I read more?

Thanks,

RE: How to configure multiple notifications per connection event

Andy — Tue, 21 May 2019 12:10:14 GMT

Check this thread out. It might help you clear up some questions.

RE: How to configure multiple notifications per connection event

eyalasko — Tue, 21 May 2019 12:07:00 GMT

Thanks for your reply.

How do I increase the event length. How's the event length related to the queue size ?

RE: How to configure multiple notifications per connection event

Andy — Tue, 21 May 2019 12:06:48 GMT

Ah, no idea.

RE: How to configure multiple notifications per connection event

Kenneth — Tue, 21 May 2019 12:05:19 GMT

You should also make sure to increase the GAP event length, this will control the time the softdevice will reserve for the actual connection event, and will directly impact the numbers of packets can be sent.

In addition you may find some pointers here on how to increase throughput:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/ble_sdk_app_att_mtu.html?cp=5_1_4_2_1_0

RE: How to configure multiple notifications per connection event

eyalasko — Tue, 21 May 2019 12:04:31 GMT

[quote userid="15909" url="~/f/nordic-q-a/47568/how-to-configure-multiple-notifications-per-connection-event/188226"]If you increase the queue size, naturally the memory footprint will increase as well.[/quote]

This is understood.

However I didn't increase the queue size. It is set to 1 and still nrf_sdh_ble_enable() fails

RE: How to configure multiple notifications per connection event

Andy — Tue, 21 May 2019 11:43:18 GMT

Well the notifications need to be queued somewhere. If you increase the queue size, naturally the memory footprint will increase as well.

RE: How to configure multiple notifications per connection event

eyalasko — Tue, 21 May 2019 11:41:31 GMT

I've changed memory settings in the project properties page (Keil IDE)

Nevertheless, I expect that setting hvn_tx_queue_size=1 which is the default value should not change the softdevice's memory footprint

RE: How to configure multiple notifications per connection event

Andy — Tue, 21 May 2019 11:30:36 GMT

You need to adjust your memory regions in the linker file.

RE: How to configure multiple notifications per connection event

eyalasko — Tue, 21 May 2019 10:55:55 GMT

Thanks.

I've changed to BLE_CONN_CFG_GATTS as you advised and increased APP_RAM_START (+0x100 bytes)

Strangely, nrf_sdh_ble_enable() returns NRF_ERROR_NO_MEM, even if I explicitly set hvn_tx_queue_size= 1...

	ble_cfg_t ble_cfg;
	ble_cfg.conn_cfg.params.gatts_conn_cfg.hvn_tx_queue_size = 1;	// Tried 6
	err_code = sd_ble_cfg_set(BLE_CONN_CFG_GATTS, &ble_cfg, ram_start); 
	APP_ERROR_CHECK(err_code);	

    // Enable BLE stack.
    err_code = nrf_sdh_ble_enable(&ram_start);  // this call returns NRF_ERROR_NO_MEM
    APP_ERROR_CHECK(err_code);

RE: How to configure multiple notifications per connection event

Andy — Tue, 21 May 2019 10:19:51 GMT

Mm it seems you're right. However, if you queue a new notification as soon as you get the tx complete event, you shouldn't have any issues.

In any case what you're doing is alright, but you need to change APP_BLE_CONN_CFG_TAG to BLE_CONN_CFG_GATTS.

RE: How to configure multiple notifications per connection event

eyalasko — Tue, 21 May 2019 10:09:35 GMT

Hi Andy,

Thanks for your prompt response.

Unfortunately I think that the default queue depth is 1 which severely limits the throughput...

RE: How to configure multiple notifications per connection event

Andy — Tue, 21 May 2019 10:06:35 GMT

You don't really have to increase the queue size. Just queue the notifications using sd_ble_gatts_hvx() until you fill the queue. The soft device will take care of sending as many notifications as possible on each connection event.