CC2500RGPR Datasheet, PDF (70/99 Pages) Texas Instruments – Low-Cost Low-Power 2.4 GHz RF Transceiver

CC2500
0x16: MCSM2 – Main Radio Control State Machine Configuration
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 found 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.
The RX timeout in µs 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 an example, EVENT0=34666, WOR_RES=0 and RX_TIME=6 corresponds to 1.95 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 where 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: With 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.
SWRS040C
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