Will Nucleo-WL55JC2 modules work on gateways configured for US915?

[JGree.16]

We accidentally bought a few Nucleo-WL55JC2 modules whereas we really wanted Nucleo-WL55JC1 modules. My understanding is that the JC2s are intended for AS433 applications.  I would have expected the join to be unseccessful, though. However, we successfully got the JC2s to join our US915 configured gateways.

Is this expected behavior?

[Pat_ST · Accepted solution]

Hello,

Effectively, the NUCLEO-WL55JC1 are designed for 865 to 928 MHz frequency bands, and the NUCLEO-WL55JC2 are designed for 433 to 510 MHz frequency bands.

The differences between both versions are the external discrete front-end matching between the transceiver and the antenna port. The transceiver remain exactly the same. So the JC2 is able to transmit in 865 to 928 MHz but as its JC2 front end is centered between 433 and 510 MHz, then the output power at the antenna will be strongly attenuated (in a range of 20 dB or more). So what you observed is consistent but only functional for smaller distances. Because of the front-end attenuation, the power range is really reduced.

If the gateways are not so far, you can successfully join, I think this is your configuration. If the gateways are too far, you will have trouble to join.

Best regards,

[JGree.16]

Makes a lot of sense, @Pat_ST​ . Thanks for the speedy, thorough reply. I really appreciate it.

Best,

John