I have 3 Nucleo-WL55JC and 2 B-WL5M-SUBG1 systems all running same code and located within a 1 foot of each other. Additionally I have custom sensors based on the STM32WL5MOC located 4 to 8 feet away. The Nucleo-WL55JC modules report rssi values between -50 and -60 dBm. The B-WL5M-SUBG1 modules report rssi values between -100 and -110 dBm.
Physical range test suggest these reads are real. As I move the sensors away the B-WL5M-SUBG1 lose the ability to receive the packets much sooner than the Nucleo-WL55JC.
Note the reads above are based on unmodified modules.
There is a footprint on the B-WL5M-SUBG1 modules for a pi filter in the antenna line. The factory configuration is a single serial 0 ohm resistors which is not performing very well.
The datasheet for the for the STM32WL5MOC states that for 915MHz operation:
"Max output power 21 dBm is obtained for Z load = 63 + j×22".
I have tried adjusting the impedance seen by the STM32WL5MOC on the B-WL5M-SUBG1 using the pi filter and have been unable to significantly improve the performance - I can't get anywhere near matching the Nucleo-WL55JC rssi.
Can the B-WL5M-SUBG1 be configured to work as well as the Nucleo-WL55JC? If so any suggestions on how to make that happen would be very helpful.
