Texas Instruments 3138 155 232931 - Manual (Page 64)

CC2420
SWRS041B Page 64 of 89
MDMCTRL0 (0x11) - Modem Control Register 0
Bit Field Name Reset R/W Description
15:14 - 0 W0 Reserved, write as 0
13 RESERVED_FRAME_MODE 0 R/W Mode for accepting reserved IEE 802.15.4 frame types when
address recognition is enabled (
MDMCTRL0.ADR_DECODE = 1 ).
0 : Reserved frame types (100, 101, 110, 111) are rejected by
address recognition.
1 : Reserved frame types (100, 101, 110, 111) are always
accepted by address recognition. No further address decoding is
done.
When address recognition is disabled ( MDMCTRL0.ADR_DECODE =
0 ), all frames are received and RESERVED_FRAME_MODE is don’t
care.
12 PAN_COORDINATOR 0 R/W Should be set high when the device is a PAN Coordinator. Used
for filtering packets with no destination address, as specified in
section 7.5.6.2 in 802.15.4, D18
11 ADR_DECODE 1 R/W Hardware Address decode enable.
0 : Address decoding is disabled
1 : Address decoding is enabled
10:8 CCA_HYST[2:0] 2 R/W CCA Hysteresis in dB, values 0 through 7 dB
7:6 CCA_MODE[1:0] 3 R/W 0 : Reserved
1 : CCA=1 when RSSI_VAL < CCA_THR - CCA_HYST
CCA=0 when RSSI_VAL ≥ CCA_THR
2 : CCA=1 when not receiving valid IEEE 802.15.4 data,
CCA=0 otherwise
3 : CCA=1 when RSSI_VAL < CCA_THR - CCA_HYST and not
receiving valid IEEE 802.15.4 data.
CCA=0 when RSSI_VAL ≥ CCA_THR or receiving a packet
5 AUTOCRC 1 R/W In packet mode a CRC-16 (ITU-T) is calculated and is
transmitted after the last data byte in TX. In RX CRC is
calculated and checked for validity.
4 AUTOACK 0 R/W If AUTOACK is set, all packets accepted by address recognition
with the acknowledge request flag set and a valid CRC are
acknowledged 12 symbol periods after being received.
3:0 PREAMBLE_LENGTH
[3:0]
2 R/W The number of preamble bytes (2 zero-symbols) to be sent in TX
mode prior to the SYNCWORD, encoded in steps of 2. The reset
value of 2 is compliant with IEEE 802.15.4, since the 4
th zero
byte is included in the SYNCWORD.
0 : 1 leading zero bytes (not recommended)
1 : 2 leading zero bytes (not recommended)
2 : 3 leading zero bytes (IEEE 802.15.4 compliant)
3 : 4 leading zero bytes
…
15 : 16 leading zero bytes