More info:
TX_UNDERFLOW reg: 0x0
TX_ACTIVE reg: 0x0
XOSC16M_STABLE reg: 0x0
LOCK reg: 0x0
SFD_IS_1 reg: 0x0
CC2420_FMSTATE: 0x1
cc2420: Crystal oscillator enabled.
cc2420: MDMCTRL1 register value: 0x508
cc2420: DACTST register value: 0x1800
cc2420: centre frequency set: 2437
tx_power: 31
TX_UNDERFLOW reg: 0x0
TX_ACTIVE reg: 0x0
XOSC16M_STABLE reg: 0x0
LOCK reg: 0x0
SFD_IS_1 reg: 0x0
CC2420_FMSTATE: 0x3f