3.9.13 Shut Down State Machine

The shut down state machine initially waits for the end of an ongoing transmission by waiting for a PA output off signal coming from the flag FSCR.PAON. Then, it switches off all blocks previously enabled by another state machine. This includes the DSP blocks as the demodulator, channel filter, Gauss filter, preemphasis filter or ASK-shaping filter as well as the analog blocks in the RF front end such as PA, LNA, IF amplifier, PLL and ADC. Only the XTO is kept on to allow the system to go back to IDLEMode(XTO).

If configured in SETRPA/B, the transparent outputs get disabled, too.

It is strongly recommended to start the shut down state machine after a software-induced state machine stop via the SSMRR.SSMST signal to revert to most of the changes made previously by the sequencer state machine. In this case, the FSEN.ANTT bit needs to be reset before starting the shut down state machine, as it has the potential to block the shutdown process. Neither the changes to setting registers as EOTC and SOTC nor changes of tuning registers as FEVCT or FEAT are undone.