Increase Supported Links to Peripherals on a Central Device

[Mark J]

Hi

From this article, It appears that up to 20 connections are possible when using S140 SDK 15.3.0 SDK on an nRF52840:

https://devzone.nordicsemi.com/f/nordic-q-a/33095/how-many-concurrent-connections-is-possible-to-support-with-s140_nrf52_6-0-0/126977#126977

I am unsure what has to be setup to ensure that I can get beyond the 3 connections that I am able to make now using sd_ble_gap_connect(). After I have made 3 connections and I am trying to make a 4th, sd_ble_gap_connect() returns NRF_ERROR_CONN_COUNT.

I have made changes to sdk_config.h as follows:

// <o> NRF_SDH_BLE_PERIPHERAL_LINK_COUNT - Maximum number of peripheral links. 
#ifndef NRF_SDH_BLE_PERIPHERAL_LINK_COUNT
#define NRF_SDH_BLE_PERIPHERAL_LINK_COUNT 1
#endif

// <o> NRF_SDH_BLE_CENTRAL_LINK_COUNT - Maximum number of central links. 
#ifndef NRF_SDH_BLE_CENTRAL_LINK_COUNT
#define NRF_SDH_BLE_CENTRAL_LINK_COUNT 20
#endif

// <o> NRF_SDH_BLE_TOTAL_LINK_COUNT - Total link count. 
// <i> Maximum number of total concurrent connections using the default configuration.

#ifndef NRF_SDH_BLE_TOTAL_LINK_COUNT
#define NRF_SDH_BLE_TOTAL_LINK_COUNT 20
#endif

... thinking that it would give me the requried 20 links to peripherals as a central device.

Did I setup sdk_config.h incorrectly or is there an additional entry or api call that is required to increase the number of links to peripherals from my central device?

Thanks,

Mark J

[Mttrinh]

Hi,

Yes, the S140 should support up to 20 connections. Could you try setting NRF_SDH_BLE_PERIPHERAL_LINK_COUNT to 0?

Have you modified anything else other than the connection count?

We do have a central multilink example. The example can have a maximum of 8 concurrent connections to peripheral devices, but you should get an idea of how it can be done.

[Mark J]

Hi Mttrinh,

In the end, I recreated my project using the central multilink example that you suggest. I also took the opportunity to get rid of many unused project components to get my RAM usage way down.

I do not seem to have a connection limit issue anymore. I will verify your suggestion as the answer.

Thanks,

Mark J