Texas Instruments 3138 155 232931 - Manual (Page 61)

CC2420
SWRS041B Page 61 of 89
37 Configuration Registers
The configuration of CC2420 is done by
programming the 16-bit configuration
registers. Complete descriptions of the
registers are given in the following tables.
After chip reset (from the RESETn pin or
programmable through the MAIN.RESETn
configuration bit), all the registers have
default values as shown in the tables.
Note that the MAIN register is only reset
by using the pin reset RESETn. When
writing to this register, all bits will get the
value written, not the default value. This
also means that the MAIN.RESETn bit
must be written both low and then high to
perform a chip reset through the serial
interface.
15 registers are Strobe Command
Registers, listed first in Table 11 below.
Accessing these registers will initiate the
change of an internal state or mode. There
are 33 normal 16-bits registers, also listed
in Table 11. Many of these registers are
for test purposes only, and need not be
accessed for normal operation of
CC2420 .
The FIFOs are accessed through two 8-bit
registers, TXFIFO and RXFIFO. The
TXFIFO
register is write only. Data may
still be read out of the TXFIFO through
regular RAM access (see section RAM
access section on page 29), but data is
then not removed from the FIFO. Note that
the crystal oscillator must be active for all
FIFO and RAM access.
During address transfer, and while data is
being written to the TXFIFO, a status byte
is returned on the serial data output pin
SO
. This status byte is described in Table
5 on page 29.
All configuration and status registers are
described in the tables following Table 11.
Address Register Register type Description
0x00 SNOP S No Operation (has no other effect than reading out status-bits)
0x01 SXOSCON S Turn on the crystal oscillator (set XOSC16M_PD = 0 and
BIAS_PD = 0)
0x02 STXCAL S Enable and calibrate frequency synthesizer for TX;
Go from RX / TX to a wait state where only the synthesizer is
running.
0x03 SRXON S Enable RX
0x04 STXON S Enable TX after calibration (if not already performed)
Start TX in-line encryption if SPI_SEC_MODE
≠ 0
0x05 STXONCCA S If CCA indicates a clear channel:
Enable calibration, then TX.
Start in-line encryption if SPI_SEC_MODE
≠ 0
else
do nothing
0x06 SRFOFF S Disable RX/TX and frequency synthesizer
0x07 SXOSCOFF S Turn off the crystal oscillator and RF
0x08 SFLUSHRX S Flush the RX FIFO buffer and reset the demodulator. Always
read at least one byte from the RXFIFO before issuing the
SFLUSHRX
command strobe
0x09 SFLUSHTX S Flush the TX FIFO buffer
0x0A SACK S Send acknowledge frame, with pending field cleared.
0x0B SACKPEND S Send acknowledge frame, with pending field set.
0x0C SRXDEC S Start RXFIFO in-line decryption / authentication (as set by
SPI_SEC_MODE)
0x0D STXENC S Start TXFIFO in-line encryption / authentication (as set by
SPI_SEC_MODE), without starting TX.