Slow rate from central to peripheral

[Nabil]

Hello,

I'm working on nrF52832 with two different Android device : Samsung Galaxy note 3 neo and HTC ONE M8.

My test :

• Central side ( smartphone ) : each 200 ms I send 20 Bytes during 20s -> 100 * 20 Bytes
• Peripheral side : I measure the time between the first packet and the last one.

The result :

• HTC ONE M8 : 20.2 s to receive data
• SAMSUNG = 43 s to receive data

We are trying to improve the data transmission because the rate is too slow on some smartphone ( ex : samsung note 3 neo ).

I think that the connection interval on ble_evt_connected return 39 -> 48,5ms ( for both smartphone )

#define MIN_CONN_INTERVAL                MSEC_TO_UNITS(10, UNIT_1_25_MS)           /**< Minimum acceptable connection interval (0.1 seconds). */
#define MAX_CONN_INTERVAL                MSEC_TO_UNITS(200, UNIT_1_25_MS)           /**< Maximum acceptable connection interval (0.2 second). 200*/
#define SLAVE_LATENCY                    0                                          /**< Slave latency. */
#define CONN_SUP_TIMEOUT                 MSEC_TO_UNITS(4000, UNIT_10_MS)            /**< Connection supervisory timeout (4 seconds). */

How can I increase the speed ?

Thank you very much.

Nabil

[Nabil]

Hello,

Thank you for your answer.

I just have changed :

#define MIN_CONN_INTERVAL                MSEC_TO_UNITS(10, UNIT_1_25_MS)           /**< Minimum acceptable connection interval (0.1 seconds). */
#define MAX_CONN_INTERVAL                MSEC_TO_UNITS(200, UNIT_1_25_MS)           /**< Maximum acceptable connection interval (0.2 second). 200*/
#define SLAVE_LATENCY                    0                                          /**< Slave latency. */
#define CONN_SUP_TIMEOUT                 MSEC_TO_UNITS(4000, UNIT_10_MS)            /**< Connection supervisory timeout (4 seconds). */

to :

#define MIN_CONN_INTERVAL                MSEC_TO_UNITS(7.5, UNIT_1_25_MS)           /**< Minimum acceptable connection interval (0.1 seconds). */
#define MAX_CONN_INTERVAL                MSEC_TO_UNITS(200, UNIT_1_25_MS)           /**< Maximum acceptable connection interval (0.2 second). 200*/
#define SLAVE_LATENCY                    0                                          /**< Slave latency. */
#define CONN_SUP_TIMEOUT                 MSEC_TO_UNITS(4000, UNIT_10_MS)            /**< Connection supervisory timeout (4 seconds). */

and it seems to work correctly. Is it normal ? The chosen connection interval seems to be 39 ..