NRF_SDH_BLE_TOTAL_LINK_COUNT vs PERIPHERAL_LINK_COUNT and CENTRAL_LINK_COUNT

[jmag999]

In my project, I typically have 20 central connections to the Nordic device.  Occasionally, I need to allow a phone to connect to the device using a peripheral link.  When this occurs, I do not need the other 20 central connections to be maintained.  So I set the following in sdk_config:

#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 - 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

However, when I call sd_ble_cfg_set(BLE_GAP_CFG_ROLE_COUNT, &ble_cfg, *p_ram_start);, I get the NRF_ERROR_CONN_COUNT error.

I am not asking for more than 20 simultaneous connections, just the ability to choose what types are used at any given time.  I am using SDK14.  Is this a bug or done on purpose?

[bjorn-spockeli]

Hi JOn, 

This is the intended behaviour, as you have stated the S132 SoftDevice only supports 20 concurrent connections. Hence, NRF_SDH_BLE_CENTRAL_LINK_COUNT + NRF_SDH_BLE_PERIPHERAL_LINK_COUNT <= NRF_SDH_BLE_TOTAL_LINK_COUNT. So the maximum number of central link you will be able to configure with one peripheral link is 19. 

You can set the central link count to 20 and the peripheral link count to 0 and then modify the central and peripheral link counts at run-time when you need to connect to the device with a phone, but this will require you to reinitialize the SoftDevice. 

Best regards

Bjørn 

[Martin H.]

Is this still valid today and with s140-7.0.1 ?