STBY_XOSC after CAD

[christianh104]

When executing a CAD operation, the SX1262 returns to STBY_RC, even if the RX/TX fallback mode is set to RADIOLIB_SX126X_RX_TX_FALLBACK_MODE_STDBY_XOSC and standbyXOSC is true. This introduces about a 5ms delay to the CAD operation. I can confirm the standby mode is incorrect because if I execute radio.standby(); delay(5); before starting the CAD operation, I can get the operation itself down to 275 µs. In addition, if I set the CAD exitMode to RADIOLIB_SX126X_CAD_GOTO_RX, and a packet is received, the next CAD operation executes without the delay, so the behavior of the CAD operation is inconsistent. I did try issuing SPI commands manually to ensure this library was not introducing the delay - it is not.

Does anyone know if it is possible to ensure the SX1262 enters STBY_XOSC after a CAD operation? Alternatively, does anyone know how I would contact Semtech to report this? I have looked for support on their website but it seems difficult to get in touch with them outside of sales. I figured this was the best place to find people who have tinkered with these chips and know their quirks.

I should also get ahead of this: Yes, the documentation does state that after SetCAD completes, the device returns to STBY_RC mode. It also says that for SetRx and SetTx, but that is demonstrably false, and in contradiction with the existence of SetTxRxFallbackMode. Also, as noted above, if a packet is received as part of the operation, it does enter STBY_XOSC.

[jgromes]

I don't have experience with this specific issue, and unfortunately no way to contact Semtech either. Not for a lack of trying as I've been trying to reach them to report a different issue with SX1262.

Maybe we can start some sort of a "community errata" in here - it won't fix our woes, but might save others's some time :)