Problem with power of Ble signal

[Julien]

Hi

I am currently experiencing an issue with my custom board related to poor BLE signal performance.

My devices are based on the NORA-B101 (nRF5340) combined with a SKY66408-11 front-end module. While some boards are performing as expected, others show significantly weaker RSSI.

Is there a way to verify whether the RF signal delivered by the NORA module itself is within specifications? I am trying to determine whether the root cause of the issue lies with the NORA module or the Skyworks FEM.

I also have another question: my custom board is powered at 1.8V, whereas the SWD signals (SWDIO, SWCLK) from my debug probe are at 3V. Could this mismatch cause any issues or impact performance?

I use ncs v2.6.1 on zephyr.

Best regards,

Julien

[Turbo J]

Powering pins to 3.3V with VDD at 1.8V could fry those pins. There is a diode from the pins to the VDD rail that is not intended for powering the chip. The raise in VDD level could also blow up other stuff on the PCB that is connected to this rail.

Most debuggers that I am aware of require a connection from target VDD to a voltage input that sets input/output levels for the debug connection.

No idea about your RF issues, I am not an HF expert.

[Bendik Heiskel]

Hi Julien,

The only way to verify the power is to measure the output power from the module using a spectrum analyzer.

To check if the radio is being configure correctly you can check  TXPOWER register in the radio to see what output power the radio is transmitting at. This can be done using a debugger:

nrfutil device read --address 0x4100850C --direct --core NETWORK

Best regards.

Bendik