Modem Modes of Operation
MC1321x Reference Manual, Rev. 1.6
Freescale Semiconductor
7-17
Figure 7-7. ED and LQI Reported Power vs. Input Power
Status bit cca is unaffected by energy detect. Once the energy detect operation is complete, cca_irq is
asserted.
The following is a typical sequence for ED operation (not using a timer-based start):
NOTE
The control bit use_strm_mode, Control_B Register 07, Bit 5 should be set
to “0”.
1. The RX frequency must be programmed.
2. If not already low, the MCU sets RXTXEN low.
3. cca_mask, Control_A Register 06, Bit 10 is programmed to “1” to enable an interrupt request when
the CCA operation is complete.
4. cca_type[1:0], Control_A Register 06, Bits 5 - 4, is programmed to “10” to select the ED algorithm.
5. Transceiver sequence is programmed to xcvr_seq[1:0] = 0x1 for CCA Mode.
6. RXTXEN must be asserted and held high.
7. When the measurement is complete, the following are reported:
a) cca_final[7:0], RX_Pkt_Latch Register 2D, Bits 15 - 8 - reports the average power level
b) cca_irq, IRQ_Status Register 24, Bit 5, is set to “1” to indicate complete status. Also, an
interrupt is generated due to the valid status.
8. In response of the interrupt request from the MC1321x, the microcontroller can determine the
power level by reading cca_final[7:0].
9. Negate RXTXEN to low.
-85
-75
-65
-55
-45
-35
-25
-15
-85
-75
-65
-55
-45
-35
-25
-15
Input Power Level (dBm)
R
epor
ted Pow
e
r
Lev
el (
d
B
m
)
802.15.4 Accuracy
and Range Requirements
Содержание freescale semiconductor MC13211
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