I'm working with an RF231 802.15.4 radio transceiver. I can manage reception and transmission, but I have a couple of doubts about the correspondence between the protocol states and the radio's ones.
I see that the three major states are
Reading from the RF231 datasheet (DOC8111),
TRX_OFF is an idle state in which the analog circuitry is turned off.
PLL_ON state correspond to TX_ON state of the protocol. When in this state, the freq. synthesizer is turned on and locks to the required carrier frequency (channels 11 to 26).
In order to receive or transmit the PLL must have locked BUT, we can enter RX_ON state (listen/rx state) from TRX_OFF directly (but we must wait for the PLL to lock).
On the contrary, to enter BUSY_TX state we must first be in PLL_ON state.
The datasheet specifies that any carrier sensing (CCA)/ energy detection (ED) operation required the transceiver to be in one RX state (RX_ON corresponding to "listen" or BUSY_RX corresponding to "receiving a frame").
This leads to my questions: how is carrier sense used? What do we do to transmit/receive a frame?
I mean: if I need to transmit a frame, do I need to first enter RX_ON, to perform carrier sense, then enter PLL_ON and finally BUSY_TX? This sounds rather odd..
Again: is there a way to postpone the RX_ON state to the moment in which some energy is really sensed on the channel from PLL_ON state?
Otherwise it looks like such state is no different from RX_ON and I don't see the reason for it to exist..
Thanks in advance