How to shorten the data transmission cycle using sd_ble_gatts_hvx()?

[air]

 Hello.

Log data is transmitted to APP(phone) using sd_ble_gatts_hvx().

The length of one packet is 20 bytes, and the expected total number of packets is about 3,200.

The connection interval I set is min. 7.5mS as shown below log.

The connection interval sent from the APP(phone) after connection is 12 (15mS).

This connection interval is not updated.

If you look at the log below, the log data is transmitted after the BLE_GATTS_EVT_HVN_TX_COMPLETE event every 15mS.

It seems to follow the setting of the APP(phone).

I wonder if there is any way to shorten this cycle.

 

The development environment is as follows.

- MCU : nRF52833

- SD : s140

- SDK : 17.1.0

 

Below is the log data.

 

 Thanks.

// *** my setting *** //
#define MIN_CONN_INTERVAL						MSEC_TO_UNITS(7.5, UNIT_1_25_MS)	// 7.5, Minimum connection interval */
#define MAX_CONN_INTERVAL						MSEC_TO_UNITS(100, UNIT_1_25_MS)	// Maximum connection interval. */
#define SLAVE_LATENCY							10											// 5, Slave latency
#define CONN_SUP_TIMEOUT						MSEC_TO_UNITS(5000, UNIT_10_MS)	// 3,000, Connection supervisory timeout. */

#define FIRST_CONN_PARAMS_UPDATE_DELAY		APP_TIMER_TICKS(100)					// 200, Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY		APP_TIMER_TICKS(5000)				// 3000, Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAM_UPDATE_COUNT			3											/**< Number of attempts before giving up the connection parameter negotiation. */



// *** after connect with APP(phone) *** //
00> BLE_GAP_EVT_CONN_PARAM_UPDATE - conn_interval min:6, conn_interval max:6		// from APP(phone), I don't update comm_params.
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:13815
00> BLE_GAP_EVT_CONN_PARAM_UPDATE - conn_interval min:12, conn_interval max:12	// from APP(phone), I don't update comm_params.
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:13845
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:13905
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:13965
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:13995
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14175
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14535
00> tx log (58, 0-1), time:14566							// I transmit my 1 log packet every 30mS.
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14595		// I receive BLE_GATTS_EVT_HVN_TX_COMPLETE event every 30mS.
00> tx log (58, 0-2), time:14596
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14625
00> tx log (57, 1-1), time:14626
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14655
00> tx log (57, 1-2), time:14656
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14685
00> tx log (56, 2),   time:14686
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14715
00> tx log (55, 3),   time:14716
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14745
00> tx log (54, 4),   time:14746
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14775
00> tx log (53, 5),   time:14776
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14805
00> tx log (52, 6),   time:14806
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14835
00> tx log (51, 7),   time:14836
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14865
00> tx log (50, 8),   time:14866
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14895
00> tx log (49, 9),   time:14896
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14925
00> tx log (48, 10),   time:14926
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14955
00> tx log (47, 11),   time:14956
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:14985
00> tx log (46, 12-1), time:14986
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15015
00> tx log (46, 12-2), time:15016
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15045
00> tx log (45, 13),   time:15046
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15075
00> tx log (44, 14-1), time:15076
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15105
00> tx log (44, 14-2), time:15106							// I transmit my 1 log packet every 15mS.
00> tx log (43, 15),   time:15122
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15135			// I receive BLE_GATTS_EVT_HVN_TX_COMPLETE event every 15mS.
00> tx log (42, 16-1), time:15136
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15150
00> tx log (42, 16-2), time:15151
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15166
00> tx log (41, 17-1), time:15166
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15181
00> tx log (41, 17-2), time:15181
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15196
00> tx log (40, 18-1), time:15196
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15211
00> tx log (40, 18-2), time:15211
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15226
00> tx log (39, 19),   time:15226
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15241
00> tx log (38, 20-1), time:15241
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15255
00> tx log (38, 20-2), time:15256
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15271
00> tx log (37, 21-1), time:15271
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15285
00> tx log (37, 21-2), time:15286
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15301
00> tx log (36, 22-1), time:15301
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15315
00> tx log (36, 22-2), time:15316
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15330
00> tx log (35, 23),   time:15331
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15346
00> tx log (34, 24-1), time:15346
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15361
00> tx log (34, 24-2), time:15361
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15376
00> tx log (33, 25),   time:15376
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15390
00> tx log (32, 26),   time:15391
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15405
00> tx log (31, 27),   time:15406
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15420
00> tx log (30, 28),   time:15421
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15436
00> tx log (29, 29),   time:15436
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15450
00> tx log (28, 30),   time:15451
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15466
00> tx log (27, 31),   time:15466
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15481
00> tx log (26, 32),   time:15481
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15495
00> tx log (25, 33),   time:15496
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15510
00> tx log (24, 34),   time:15511
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15526
00> tx log (23, 35-1), time:15526
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15540
00> tx log (23, 35-2), time:15541
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15555
00> tx log (22, 36),   time:15556
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15570
00> tx log (21, 37-1), time:15571
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15585
00> tx log (21, 37-2), time:15586
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15600
00> tx log (20, 38-1), time:15601
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15615
00> tx log (20, 38-2), time:15616
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15630
00> tx log (19, 39),   time:15631
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15646
00> tx log (18, 40-1), time:15646
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15661
00> tx log (18, 40-2), time:15661
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15676
00> tx log (17, 41-1), time:15676
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15690
00> tx log (17, 41-2), time:15691
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15706
00> tx log (16, 42-1), time:15706
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15720
00> tx log (16, 42-2), time:15721
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15736
00> tx log (15, 43),   time:15736
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15750
00> tx log (14, 44-1), time:15751
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15766
00> tx log (14, 44-2), time:15766
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15781
00> tx log (13, 45),   time:15782
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15795
00> tx log (12, 46-1), time:15796
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15810
00> tx log (12, 46-2), time:15811
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15825
00> tx log (11, 47),   time:15826
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15841
00> tx log (10, 48-1), time:15842
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15856
00> tx log (10, 48-2), time:15856
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15871
00> tx log (9, 49-1), time:15872
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15885
00> tx log (9, 49-2), time:15886
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15900
00> tx log (8, 50-1), time:15901
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15915
00> tx log (8, 50-2), time:15916
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15931
00> tx log (7, 51),   time:15932
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15945
00> tx log (6, 52-1), time:15946
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15961
00> tx log (6, 52-2), time:15962
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15975
00> tx log (5, 53),   time:15976
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:15991
00> tx log (4, 54-1), time:15992
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16006
00> tx log (4, 54-2), time:16007
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16021
00> tx log (3, 55-1), time:16022
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16036
00> tx log (3, 55-2), time:16037
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16051
00> tx log (2, 56-1), time:16052
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16066
00> tx log (2, 56-2), time:16067
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16081
00> tx log (1, 57),   time:16082
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16095
00> LOG TX DONE 1														// all tx done
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16111
00> BLE_GATTS_EVT_HVN_TX_COMPLETE - time:16141

[air]

My phone condition is as below picture and I use custom APP.

If I cannot adjust the connection interval

1. I wonder if multi notification is possible in one connection interval.

            If this is possible, which part should I refer to?

2. If 1. is not possible, there seems to be a way to combine several packets into one packet and send them.

Please comment on this.

 

 thanks.

[Einar Thorsrud]

Hi,

I have not found the minimum connection interval for the LG V35 ThinQ, but it is not unusual for a phone to limit it to minimum 15 ms.

air said:

I wonder if multi notification is possible in one connection interval.

Yes, that is possible. That depends on the event length. From the nRF side, you should set a long event length (up to as long as the connection interval). You do this by adjusting NRF_SDH_BLE_GAP_EVENT_LENGTH in sdk_config.h. If the phone and nRF agrees on the long event length, then you can send multiple packet during that event. You simply queue more notifications using sd_ble_gatts_hvx() and if there is more data and still time in the evnet, the next packet is sent, and so on.