gap_params_init and connection parameter issue

[HaiderRPM]

Hello,

I'm working on a firmware for a device that is created using ble proximity example. It is power constrain device and required a connection interval of 30 sec between a master (Android phone only) and slave nRF52810.

I’m using the following version and device.

1. SDK v17.0.2
2. 2. s112_nrf52_7.2.0_softdevice
3. Basically I’m using Android phones as my central or master device and nRF52810 as peripheral or slave.

Basic feature of the firmware

                The architecture is based on Application Timer Event callbacks.

                The firmware was prepared using the BLE Peripheral Proximity example.

In order to minimize power consumption the device runs a minimum of active GATT services listed below:

1. TX Power
2. Instant Alert Service (IAS)
3. Instant Alert Service Client (IAS-C)
4. Connection is BLE_PERIPHERAL

To get the desire interval I'm changing the following parameters. I have used different values for these parameters without violating the following two constrain but seem I'm not able to go beyond 15 sec interval ( 30 sec is desired). Is there anything I'm not doing correct. 

                   //constrains

1. 1. conn_sup_timeout * 4 > (1 + slave_latency) * max_conn_interval
   2. (1 + Conn_Latency) * Conn_Interval_Max * 2 < conn_sup_timeout

                   // Parameters

1. 1. MIN_CONN_INTERVAL               MSEC_TO_UNITS(800, UNIT_1_25_MS)
   2. MAX_CONN_INTERVAL               MSEC_TO_UNITS(830, UNIT_1_25_MS)
   3. SLAVE_LATENCY                   18
   4. CONN_SUP_TIMEOUT                MSEC_TO_UNITS(32000, UNIT_10_MS)

I'm getting the following error whenever I try to increase slave latency.

• gap_params_init();
  • APP_ERROR_CHECK(err_code);
    • I think It might help you “void app_error_handler_bare(ret_code_t error_code)” here error_code = 0x00000007.

[HaiderRPM]

Thank you for your reply, 

I agree with your statement. 

You can't have 30ms connection interval. You can have maximum 4 seconds (you can find the limits in ble_gap.h. Search for BLE_GAP_CP_LIMITS).

But my connection interval is 830 ms and I'm taking advantage of slave latency to achieve effective connection interval 30 sec.

But I think (1 + connSlaveLatency) * connInterval * 2 constrain don't allow to go beyond 15 sec. Or do we have any other way to get the better result. 

Do we have a way to disconnection and reconnect the peripheral with the 30 sec interval and transfer packets. but it is important to slave to sleep during that period of time.

Thanks

[Edvin]

HaiderRPM said:

But I think (1 + connSlaveLatency) * connInterval * 2 constrain don't allow to go beyond 15 sec.

 I agree.

 

HaiderRPM said:

Do we have a way to disconnection and reconnect the peripheral with the 30 sec interval and transfer packets. but it is important to slave to sleep during that period of time.

 Yes, it is possible, but I don't know whether it actually saves you any power. Setting up a connection requires more packets back and forth than just maintaining the "15 second connection interval".

Why do you have this strict requirement of 30ms? Is it to save power? If so, then using 15sec should be fine. You aren't saving much on going from 15 to 30 seconds. Besides, 30 seconds is against the specification. 

So why do you have this strict requirement of 30 seconds connection interval?