Texas Instruments CC2500 User Manual

CC2500
S
WRS040
C
Page
70
of
89
0x16: MCSM2
–
Main Radio Control State Machine
C
onfigura
tion
Bit
Field Name
Reset
R/W
Description
7:5
Reserved
R0
Reserved
4
RX_TIME_RSSI
0
R/W
Direct RX termination based on RSSI measurement (carrier
sense).
3
RX_TIME_QUAL
0
R/W
When the RX_TIME timer expires the chip stays in RX mode if
sync word is foun
d when
RX_TIME_QUAL
=0
, or either sync
word is found or PQT is set when
RX_TIME_QUAL
=1
.
2:0
RX_TIME[2:0]
7 (111)
R/W
Timeout for sync word search in RX
for both WOR mode and
normal RX operation
. The timeout is relative to the
programmed EVENT0 timeout
.
T
he RX timeout
in
µ
s is given by EVENT0·
C(
RX_TIME, WOR_RES)
·26/X
, where C is given by the table below
and
X is the crystal oscillator frequency in MHz:
RX_TIME[2:0]
WOR_RES = 0
WOR_RES = 1
WOR_RES = 2
WOR_RES = 3
0 (000)
3.6058
18.0288
32.4519
46.8750
1
(001)
1.8029
9.0144
16.2260
23.4375
2 (010)
0.9014
4.5072
8.1130
11.7188
3 (011)
0.4507
2.2536
4.0565
5.8594
4 (100)
0.2254
1.1268
2.0282
2.9297
5 (101)
0.1127
0.5634
1.0141
1.4648
6 (110)
0.0563
0.2817
0.5071
0.7324
7 (111)
Until end of packet
As
a
n example,
EVENT0=
34666
,
WOR_RES
=0
and
RX_TIME
=6
corresponds to 1.9
5
ms RX timeout
, 1 s polling
interval and 0.195% duty cycle
.
Note that WOR_RES should be 0 or 1 when using WOR because using
WOR_RES
> 1 will give a very low duty cycle.
In applications wh
ere WOR is not used all settings of
WOR_RES
can be used
.
The duty cycle
using WOR
is approximated by:
RX_TIME[2:0]
WOR_RES = 0
WOR_RES = 1
0 (000)
12.50%
1.
95%
1 (001)
6.250%
9765
ppm
2 (010)
3.125%
4883
ppm
3 (011)
1.563%
2441
ppm
4 (100)
0.781%
NA
5 (101)
0.391%
NA
6 (110)
0.195%
NA
7 (111)
NA
Note that the RC oscillator must be enabled in order to use setting 0
-
6, because the timeout counts RC oscillator
periods.
WOR mode does not need to be enabled.
The timeout counter resolution is limited: Wi
th RX_TIME
=0
, the timeout count is given by the 13 MSBs of EVENT0,
decreasing to the 7 MSBs of EVENT0 with RX_TIME
=6
.

Texas Instruments CC2500 Specifications

General

Brand	Texas Instruments
Model	CC2500
Category	Transceiver
Language	English