AT86RF215: Create premade configurations

For easier use of the tranceiver, multiple configurations should be added. Those could be:

DEFAULT: Assigns the default register values. Other configurations can be built from this one, by changing only the required settings.

BASEBAND_UHF_FSK: Sets the tranceiver to baseband mode (to send data directly from the MCU). The FSK baseband core is utilized, and the RF frontend is set to out UHF frequency.

IQ_RADIO_EEC_ON_SBAND: Turn off both baseband cores and sub GHz radio. Only 2.4 GHz radio is enabled. Transmission and reception is performed with the I/Q interface. Data transmission is initiated automatically, by detecting the transmit signa (I_DATA[0] = 1). Data reception starts/stop with proper commands from the MCU.

IQ_RADIO_ECC_ON_UHF: Same as above, but the sub GHz radio is activated instead.

IQ_RADIO_ECC_ON_LOOPBACK: This mode works like the 2 previous ones, but the transmitted data goes through the radio(s) and is then looped back. @iliaska should it be looped back on both bands (aka in both RXDP24/RXDN24 and RXDP09/RXDN09)? We can also create 2 seperate modes just like above if you need.

SLEEP_MODE: Set the tranceiver to a state were almost no energy in consumed

Questions about IQ_RADIO transmission (based on figure 6-4 of the datasheet):

• IQ_DATA[0] must be set to high "ttx_start_delay" time before sending actual data, so the PA has enough time to ramp up. Is this performed from the FPGA? The delay is 4us

  and cannot be modified.

• While the PA ramps down ("tpa_ramp" time), it is advised that padding is sent. If I remember correctly there were always zero words between actual words, so we should be

  covered? tpa_ramp can take values of 4,8,16,32 us.

and one question about reception, do we want skew on the returning data (figure 4-10)?