nRF52840 start sending data after bonding

[Dani]

Good morning,

We have developed a prototype based on the nRF52840. We have also developed an Android application.

When smartphone has device already bonded the application is perfectly working.

Nevertheless, we have found a problem at the beginning, when smartphone wants to bond the device the first time: when device is bonded the first time, after entering the PIN code, smartphone is connected with the device and smartphone is able to receive data from device. Nevertheless, if smartphone tries to send data to device, this data is not received in the device side. At this moment, if smartphone is disconnected from device and the it connects again, then communications are perfectly working in both directions. So, do you know which can be the reason of this behaviour?? I have tried with different smartphones, and result is the same in all of them.

All the best,

Dani.

[Dani]

Hi Amanda,

  I will test what you have suggested.

  I'm using s140 v6.1.0

Dani.

[Dani]

Hi,

Using the nRF Connect I'm observing the same behaviour:

Once my device is bonded, I send some values through one service. When these data is received in my device, it starts sending all its parameters to the smartphone (one sending every 62.5ms). Through nRF-Connect I have observed that not all data is received first time after device bonding.

Nevertheless, if device is already bonded, when a smartphone connects to device, all these parameters are correctly received and there are not data losses.

Which can be the reason of this?

Dani.

[Amanda Hsieh]

Hi Dani, 

What is the value of the min/max connection interval and the GAP event length?

Could you provide the sniffer trace log?

-Amanda H.

[Dani]

Hi Amanda:

NRF_SDH_BLE_GAP_EVENT_LENGTH 251

gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
gap_conn_params.slave_latency = SLAVE_LATENCY;
gap_conn_params.conn_sup_timeout = CONN_SUP_TIMEOUT;

, where:

#define MIN_CONN_INTERVAL MSEC_TO_UNITS(500, UNIT_1_25_MS) /**< Minimum acceptable connection interval (0.5 seconds). */
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(1000, UNIT_1_25_MS) /**< Maximum acceptable connection interval (1 second). */
#define SLAVE_LATENCY 0 /**< Slave latency. */
#define CONN_SUP_TIMEOUT MSEC_TO_UNITS(4000, UNIT_10_MS) /**< Connection supervisory timeout (4 seconds). */

I will try to also have a sniffer trace.

Dani

[Dani]

I have also tried to set MIN_CONN_INTERVAL to 10ms, but result is the same: problems to receive all data just after bonding process.

When disconnecting and connecting back again (device already bonded), all data is always correctly received.

[Dani]

Finally, I have set both MIN_CONN_INTERVAL and MAX_CONN_INTERVAL to 10ms, and now it's working fine.