Hello!
I am developing the firmware for an STM32WLE5CCUx that I intend to use as an I2C slave device. The I2C interface works well, and the LoRa (de)modulation too.
I have decided to make some small changes in the firmware to use the chip as an FSK transceiver instead of a LoRa transceiver.
To achieve this, I initially just swapped the definitions of USE_MODEM_LORA and USE_MODEM_FSK (not in the .ioc file, but directly in subghz_phy_app.h) and added some #if #elif statements to configure the radio based on these definitions. Using the debugger in STM32CubeIDE, I verified that the relevant parts of the code, where the radio is configured, were executed.
However, by means of an SDR, I obtain the signal as shown in the picture; I used a slow FSK_DATARATE (set to 1000) to obtain a clearer view of the signal.
As you can see, the result is not the expected one. The frequency components of the signal should be only at the edges. It almost seems a mixed modulation of LoRa and FSK together.
Afterwards, I tried to configure FSK as the default modulation (within the .ioc), but the result is still the same.
Has anyone encountered this issue before?
What could be the possible cause?
Any clues if the cause could be a certain parameter of the communication?
Thank you for the help!
