User Manual

92
8111A–AVR–05/08
AT86RF231
8.4.3 Data Interpretation
The PHY_ED_LEVEL is an 8-bit register. The ED value of the AT86RF231 has a valid range
from 0x00 to 0x54 with a resolution of 1 dB. All other values do not occur; a value of 0xFF indi-
cates the reset value. A value of PHY_ED_LEVEL = 0 indicates that the measured energy is
less than -90 dBm (see parameter 12.7.16 RSSI_BASE_VAL, Section 12.7 “Receiver Charac-
teristics” on page 160). Due to environmental conditions (temperature, voltage, semiconductor
parameters, etc.) the calculated ED value has a maximum tolerance of ±5 dB, this is to be con-
sidered as constant offset over the measurement range.
An ED value of 0 indicates an RF input power of P
RF
≤ -90 dBm. For an ED value in the range of
0 to 84, the RF input power can be calculated as follows:
P
RF
= -90 + ED [dBm]
Figure 8-5. Mapping between Received Input Power and ED Value
8.4.4 Interrupt Handling
Interrupt IRQ_4 (CCA_ED_READY) is issued at the end of a manually initiated ED
measurement.
Note that an ED request should only be initiated in receive states. Otherwise the radio trans-
ceiver generates an IRQ_4 (CCA_ED_READY); however no ED measurement was performed.
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
0 102030405060708090
PHY_ED_LEVEL (register 0x07)
Receiver Input Power P
RF
[dBm]
Measured
Ideal