ble_app_uart TX Characteristic doesn´t work

[simon1516]

Hi,

I flashed and run "ble_app_uart" example on nrf52833 DK. With an UART tool, I can recieve data from smartphone (rx characteristic) but I can´t send data from UART tool to smartphone. I pushed the "download arrow" in tx characteristic on smartphone. I sent just a character from UART tool. I didn´t do any modifications to the example.

Do I have to do something other?

Thanks in advance

Simon

[Kenneth]

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v16.0.0/ble_sdk_app_nus_eval.html#project_uart_nus_eval_test

Typically you need to type up to 20 characters or press Enter to send the characters. Have you tried that?

Best regards,
Kenneth

[simon1516]

Yes, I tried that. I performed the steps exactly as described in your linked guide. Step 8 works well, but Step 9 doesn´t work. If I sent a text, for example "Hello" from COM listener, I didn´t recieve anything in nrf connect app. Do I just have to push the "download" arrow in the app? Or how does it works? 

[Kenneth]

See documentation: 
https://github.com/NordicSemiconductor/Android-nRF-Connect/tree/master/documentation

May I ask if you have tried typing >20 characters?

[simon1516]

No. I just typed less then 20 characters. I tried for example "48 65 6C 6C 6F", as described in the example guide step 9. Do I have to enable or diable notifications and indications in nRF connect app?

[Kenneth]

You have to enable notifications yes. However data is not sent from the peripheral until buffer is full (20bytes) or there is a new line character. It should be fairly easy to type >20 characters, can you try it?

Edit: Looking at the code I can see that the buffer size if dynamically updated (m_ble_nus_max_data_len) in gatt_evt_handler(). So it may be more than 20bytes. If you want you can change implementation in gatt_evt_handler() so that you can set it fixed to for instance 20bytes or less for testing.

In any case you can check in uart_event_handle() that data will be sent either when received UART data equal m_ble_nus_max_data_len or that a new line character have been received (typically by pressing Enter on keyboard).

Best regards,
Kenneth

[simon1516]

Hi,

thanks for reply.

It works now :-) I can now send data from UART to nrf Connect App. My fault was the variable "m_ble_nus_max_data_len", which includes a buffer with more than 100 characters...I just tried to send a few characters.

It is our aim, to sent data from a sensor to nrf connect app. So I have to store the sensor value in the buffer which is transmitted via BLE. So we don´t need the hole UART code. Can you tell me, which variable should including the sensor data instead of uart data?

Another question: There is a simple example for BLE advertising, services and characteristics (https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy/posts/ble-characteristics-a-beginners-tutorial). This example unfortunaly is only for nrf52840 and S132. This example is very simple and includes not much code. Can I use this? What changes I have to do, because I use nrf52833 and S113/S140? Is there much to do?

Our application is very simple, but there are not much examples for nrf52833 SoC :-/

Thanks in advance for your help!

[simon1516]

There are informations how to make examples of PCA10056 (nrf52840) working on nrf52833.

https://devzone.nordicsemi.com/f/nordic-q-a/56083/nordic-sdk-examples-making-them-work-for-nrf52833-development-kit

Can you explain, how to:

1) Change the board config to PCA10100.

2) Change the board definition in preprocessor definitions.

3) Adjust FLASH and RAM sizes.

In which files can I change these setting in Segger Embedded Studio?

[Kenneth]

I assume the guide will be updated for the nRF52833 for the next nRF5 SDK release, though it will be similar to using PCA10056 when developing for the nRF52811:
https://infocenter.nordicsemi.com/topic/sdk_nrf5_v16.0.0/nrf52811_user_guide.html