EM2420 ETC [List of Unclassifed Manufacturers], EM2420 Datasheet - Page 50

• Manufacturer Part Number: EM2420
• Description: 2.4 GHz IEEE 802.15.4 / ZigBee RF Transceiver
• Manufacturer: ETC [List of Unclassifed Manufacturers]

Clear Channel Assessment
The clear channel assessment signal is
based on the measured RSSI value and a
programmable
channel assessment function is used to
implement the CSMA-CA functionality
specified in [1]. CCA is valid when the
receiver has been enabled for at least 8
symbol periods.
Carrier
programmed by RSSI.CCA_THR. The
threshold value can be programmed in
steps of 1 dB. A CCA hysteresis can also
be
MDMCTRL0.CCA_HYST control bits.
All 3 CCA modes specified by [1] are
implemented in the EM2420. They are set
in MDMCTRL0.CCA_MODE, as can be seen
in the register description. The different
modes are:
Ember Part Number: 120-0049-000C
programmed
sense
threshold.
threshold
in
The
level
clear
EM2420 Datasheet
the
is
0
1
2
3
Clear channel assessment is available on
the CCA output pin. CCA is active high, but
the polarity may be changed by setting the
IOCFG0.CCA_POLARITY control bit.
Implementing CSMA-CA may easiest be
done by using the STXONCCA command
strobe, as described in the Radio control
state machine section on page 42.
Transmission will then only start if the
channel is clear. The TX_ACTIVE status
bit (see Table 5) may be used to detect
the result of the CCA.
Reserved
Clear channel when received energy is below
threshold.
Clear channel when not receiving valid IEEE
802.15.4 data.
Clear channel when energy is below threshold
and not receiving valid IEEE 802.15.4 data
EM2420
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