nRF52 DK + NUS (BLE UART) app + Python

RE: nRF52 DK + NUS (BLE UART) app + Python

Hung Bui — Thu, 02 Mar 2023 08:56:20 GMT

Hi Bret,
All BLE server would support service discovery procedure. If you can use a phone and connect to the device and can get the services& characteristic that mean the service discovery has been performed.
I would suggest to use nRF Sniffer to track what happen over the air.

RE: nRF52 DK + NUS (BLE UART) app + Python

Bret Foreman — Thu, 02 Mar 2023 02:05:07 GMT

After I connect, I see the DK connect light turn on, so I know I'm connecting. But the Bleak Client services list is empty. Is it possible that the NUS demo does not have services discovery enabled?
I'll try the same code with the HRS demo and see if any services are discovered.

RE: nRF52 DK + NUS (BLE UART) app + Python

Hung Bui — Wed, 01 Mar 2023 09:06:43 GMT

Hi Bret,
I'm not very familiar with the PythonBleak library but as with any BLE central, you would need to perform a service discover to be able to get the handle ID of the characteristic.
In other words you can not directly write to a characteristic with just the UUID. You need to discover the attribute table to get the handle ID of the characteristic that matches the UUID you are looking for.
Please double check if the UUID of the characteristic you are planning to write to match with what on the peripheral.

I would suggest to get familiar with the library by testing with some standard BLE service before you move to NUS, for example heart rate service.