Communication between two nRF52840 boards through BLE

[BMG]

Hello,

I have 2 pieces of nRF52840 and I managed to connect each other. One is central, uploaded the code: 'nRF5_SDK_15.3.0_59ac345\examples\ble_central\ble_app_multilink_central' and the second is peripheral, with the code: 'nRF5_SDK_15.3.0_59ac345\examples\ble_peripheral\ble_app_blinky\'.

The problem is that I don't know how to communicate each other/ send a string from central to peripheral and when the peripheral receives that string, to do something.

Do you have an example code or how can I do this?

Thank you.

[Mttrinh]

Hi,

You should able to do this with the UART example from our SDK. Have look at these two examples: 

Nordic UART Service Client(Central), can be found in <InstallFolder>\examples\ble_central\ble_app_uart_c

UART/Serial Port Emulation over BLE(Peripheral), can be found in <InstallFolder>\examples\ble_peripheral\ble_app_uart

[Mttrinh]

You can use this function to send a string: ble_nus_c_string_send().

[BMG]

Thank you for the answer! But I have a problem with the  <InstallFolder>\examples\ble_central\ble_app_uart_c project, in function:

ret_code = sd_softdevice_enable(&clock_lf_cfg, app_error_fault_handler); 

called from  nrf_sdh_enable_request() in ble_stack_init() function:

I think it's a reset and I don't know how to solve it because the file containing the implementation of  sd_softdevice_enable() function is not compiled in the project. I think it's a separate library where its implementation can be found and I don't have access to this. That's why I can''t do debug.

How can I solve this?

[Mttrinh]

Hi,

That is a softdevice function which isn't open source, so like you said you won't have access to it.

Have you modified anything in the example? I suspect it might be just a problem with memory. Try setting the define "DEBUG" in your preprocessor and set a breakpoint at the function app_error_fault_handler(). Then try to debug the code, this will let you see which error code that is returned from the function.

[BMG]

Hi Mttrinh,

I checked the function app_error_fault_handler() and the program doesn't get there, so I am not able to see which error code returns the function.

I suppose that the problem is the softdevice and I have several questions:

1. How can I verify which version of softdevice it's on the board?

2. Do I have a softdevice on my board by default? I have sparkfun nrf52840 mini.

3. How to do an update to softdevice 7.0.1?

4. The examples from nRF5_SDK_15.3.0_59ac345 with which versions of softdevice are running? 

5. The example "nRF5_SDK_15.3.0_59ac345\examples\ble_peripheral\ble_app_blinky" doesn't have any problem with ble_stack_init() function and it works well. I don't know why only some examples work and others are stuck at ble_stack_init().

Thank you.

[Mttrinh]

Hi,

1. You can use the "Programmer" inside nRF Connect fro Desktop to verify which version of the softdevice you have running on your board. Run "Programmer" - > Select device on the top left corner. Then you will see the softdevice version in the log if it is detected.

2. It depends on which IDE you are using. If you are using Segger Embedded Studio(SES) then the softdevice will be flashed with the application automatically.

3. What do you mean by updating? via DFU? Or just flash it over to the board? Note that Softdevice s140v7.0.1 is supported in SDK16.0.0.

4. The SDK15.3.0 are using Softdevice s140v6.1.1.

5. Have you modified anything on the other examples? Did you run every examples you tried with unmodified?

[BMG]

Hello,

1. I tried to use nrf Connect for Desktop, but I get this error: 

I've also installed JLink v6.22g. I read that this tool is not available for pro nrf52840 mini.

2. I'm not using any IDE, only run in a linux emulator the commands to: compile, create the zip and upload the project on the board.

3. By update, it means that if on the board, it's s140v6.1.1, I want to update to s140v7.0.1.

5. I also tried with the original code, with no changes, and it's the same problem.

Thank you.