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Radio
Description
Telos features the Chipcon CC2420 radio for wireless communications. The CC2420 is an
IEEE 802.15.4 compliant radio providing the PHY and some MAC functions. With sensitivity
exceeding the IEEE 802.15.4 specification and low power operation, the CC2420 provides
reliable wireless communication. The CC2420 is highly configurable for many applications with
the default radio settings providing IEEE 802.15.4 compliance. Features and usage of the
CC2420 is available in Chipcon's datasheet at http://www.chipcon.com
The CC2420 is controlled by the TI MSP430 microcontroller through the SPI port and a series of
digital I/O lines and interrupts (see the Schematics on page 7 for more information). The radio
may be shut off by the microcontroller for low power duty cycled operation.
The CC2420 has programmable output power. Common CC2420 register values and their
corresponding current consumption and output power are shown in Figure 7.
PA_LEVEL
31
27
23
19
15
11
7
3
The CC2420 provides a digital received signal strength indicator (RSSI) that may be read any
time. Additionally, on each packet reception, the CC2420 samples the first eight chips,
calculates the error rate, and produces a link quality indication (LQI) value with each received
packet. A mapping from RSSI to the RF level in dBm is shown in Figure 8.
Figure 8 : Received Signal Strength Indicator mapping to RF Power [dBm]
Moteiv Corporation
Output Power [dBm]
TXCTRL register
0xA0FF
0
0xA0FB
-1
0xA0F7
-3
0xA0F3
-5
0xA0EF
-7
0xA0EB
-10
0xA0E7
-15
0xA0E3
-25
Figure 7 : Output power configuration for the CC2420
Telos (Rev B) : PRELIMINARY Datasheet (12/5/2004)
Rev B (Low Power Wireless Sensor Module)
Current Consumption [mA]
17.4
16.5
15.2
13.9
12.5
11.2
9.9
8.5
Telos
Page 13 of 28
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