8 concurrent connections fail on 51822

[alex kim]

Hi, Nordic Team

My development environment is PCA10028, SoftDevice 130, SDK12.3.0

I use a s130_nrf51_2.0.1_softdevice.hex.

It is based on ble_app_multilink_central and experimental_ble_app_blinky.

See also devzone.nordicsemi.com/.../can-the-nrf51822-be-used-as-a-twi-slave

#define CENTRAL_LINK_COUNT 7 //8 /**< Number of central links used by the application. When changing this number remember to adjust the RAM settings*/
#define PERIPHERAL_LINK_COUNT 1 //0

Up to six peripherals can be reliably connected to the Central as shown in the attached video.

However, when the peripheral devices become seven, they are repeatedly connected and disconnected at the moment.

In the video blue is a connection Yellow is disconnection

Best regards,

Alex

[alex kim]

[Bjørn Kvaale]

Hi Alex,

Sorry for the delayed response. I have tested the same with 6,7 & 8 nRF51 dongles connected to a nRF51 dev kit. The dongles are running the ble_peripheral blinky example & the dev kit is running the multilink central example from sdk 12.3. When I looked at the log when 7 or 8 peripheral devices were connected, I noticed a disconnect reason 8. This is the BLE_HCI_CONNECTION_TIMEOUT shown in ble_hci.h of the multilink central example.

According to this case, it could be due to a supervision timeout. I am unsure why this works fine for 6 boards, but then does not work for 7 or 8 boards.

It could be something with the customer board's clock accuracy. Are you able to change the accuracy or PPM of the crystal? What kind of nRF51 module are you using?

You do not by any chance have 9 nrf51 dev kits to test with? My guess is everything works out of the box with 9 dev kits.

Kind Regards,

Bjørn