nrf52 ble-app-uart-c-multilink Connection issue

[masterLee]

Hi,

I have three nRF52840 DKs

I am trying to connect two of them as peripheral devices( that implement the ble_app_uart example)

to the third  nRF52840 central device (that implements the ble_app_uart_c multilink example)

The multilink example can be found here.

Initially I tried to connect the two nRF52840 peripheral devices to the central NRF52840 device.

The peripherals were connected without issues to the central device. I verified that by checking

the debugger messages of the Central device in SES debugger as depicted in the following image

The next step was to send a "Hello_World" string c from each peripheral device to the central device every 500mse and see if the strings are transmitted ok.

But when I connected the first peripheral device to the central device the following warning came up from the central device debugger window every time the string was transmitted from the peripheral device

To verify that I send the string from the peripheral to the central without issues I connected

the peripheral device to a BLE uart app in my smartphone and the string was passed as expected.

So that leads me to conclude that it has something to do with central device DK.

So far I haven't found a solution to this or an explanation of why this happens.

Any ideas what I am doing wrong?

Thank you for your time

[Amanda Hsieh]

Hi, 

Please modify NRF_SDH_BLE_PERIPHERAL_LINK_COUNT and NRF_SDH_BLE_CENTRAL_LINK_COUNT number in sdk_config.h of nrf52-ble-app-uart-c-multilink. 

// <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 2
#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 2
#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 4
#endif

Modify the RAM_START to 0x200056C0 and RAM_SIZE to 0x3A940 via right click on the porject_name -> option -> Common -> Linker -> Section Placement Macros as the following figure. 

-Amanda H.

[masterLee]

I will make the changes and I will inform you. Thank you

[masterLee]

It worked! Thank you very much Amanda and thank you for your time!

One last question why do we have to modify the RAM ?

[NTT]

hi, Amanda, you're well. But i have problem, I run this example on SDK17 and also got this error (that MasterLee has described), I did your guide but it still not work: "00> <warning> ble_nus_c: Connection handle invalid"

If i change:  #define ECHOBACK_BLE_UART_DATA  1   to  0 (in main.c) --> it work. But i think it is not great solution, please help me.

Thank you so much!