4.8.3 PLL Enable State Machine

The PLL enable state machine starts the PLL for RX or temperature measurement. Depending on the configuration of SSMTM in the SSMCR register, the LNA is additionally enabled (see the following table).

If SSMTM is set, this state machine enables the temperature mode in the RF front end.

As a plausibility check, the XRDY flag in the FESR is expected to be set to ‘1’ to ensure that the XTO is up and running. If this check is not successful, the sequencer state machine ends with the error flag set.

Usually, the PLL enable state machine is the first entry in a setup sequence to start RX. It can be followed by the VCO tuning or immediately followed by the PLL lock state machine if no tuning is required.