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Registers
CCACTRL0 (0x6196)
–
CCA Threshold
Bit
Name
Reset
R/W
Description
No.
7:0
CCA_THR[7:0]
0xE0
R/W
Clear-channel-assessment threshold value, signed 2s-complement
number for comparison with the RSSI.
The unit is 1 dB, offset is about 76 dBm. The CCA signal goes high
when the received signal is below this value. The CCA signal is
available on the CCA pin and in the
FSMSTAT1
register.
Note that the value should never be set lower than
CCA_HYST
–
128 in
order to avoid erroneous behavior of the CCA signal.
NOTE: The reset value translates to an input level of approximately
–
32
–
76 =
–
108 dBm, which is well below the sensitivity limit. That
means the CCA signal never indicates a clear channel.
This register should be updated to 0xF8, which translates to an input
level of about
–
8
–
76 =
–
84 dBm.
CCACTRL1 (0x6197)
–
Other CCA Options
Bit
Name
Reset
R/W
Description
No.
7:5
–
000
R0
Read as zero
4:3
CCA_MODE[1:0]
11
R/W
00:
CCA always set to 1
01:
CCA = 1 when
RSSI
<
CCA_THR –
CCA_HYST
; CCA =
0 when
RSSI
≥
CCA_THR
10:
CCA = 1 when not receiving a frame, else CCA = 0
11:
CCA = 1 when
RSSI
<
CCA_THR –
CCA_HYST
and not
receiving a frame; CCA = 0 when
RSSI
≥
CCA_THR
or when
receiving a frame
2:0
CCA_HYST[2:0]
010
R/W
Sets the level of CCA hysteresis. Unsigned values given in dB
RSSI (0x6198)
–
RSSI Status Register
Bit
Name
Reset
R/W
Description
No.
7:0
RSSI_VAL[7:0]
0x80
R
RSSI estimate on a logarithmic scale, signed number in 2s complement
Unit is 1 dB. The offset to use in order to convert the register value into
the real RSSI value can be found in the device
'
s data sheet
). The RSSI value is averaged over 8 symbol periods. The
RSSI_VALID
status bit should be checked before reading
RSSI_VAL
the first time.
The reset value of
–
128 also indicates that the RSSI value is invalid.
RSSISTAT (0x6199)
–
RSSI Valid Status Register
Bit
Name
Reset
R/W
Description
No.
7:1
–
0000 000
R0
Read as zero
0
RSSI_VALID
0
R
RSSI value is valid. Occurs eight symbol periods after entering RX
RXFIRST (0x619A)
–
First Byte in RXFIFO
Bit
Name
Reset
R/W
Description
No.
7:0
DATA[7:0]
0x00
R
First byte of the RXFIFO.
Note: Reading this register does not modify the contents of the FIFO.
RXFIFOCNT (0x619B)
–
Number of Bytes in RXFIFO
Bit
Name
Reset
R/W
Description
No.
7:0
RXFIFOCNT[7:0]
0x00
R
Number of bytes in the RXFIFO. Unsigned integer.
275
SWRU191C
–
April 2009
–
Revised January 2012
CC253x Radio
Copyright
©
2009
–
2012, Texas Instruments Incorporated