JN516X Datasheet, PDF (28/94 Pages) NXP Semiconductors – IEEE802.15.4 Wireless Microcontroller

Additionally antenna diversity can be enabled whilst in receive mode waiting for a packet. The JN516x measures the
received energy in the relevant radio channel every 40μs and the measured energy level is compared with a pre-set
energy threshold, which can be set by the application program. The JN516x device will automatically switch the
antennae if the measurement is below this threshold, except if waiting for an acknowledgement from a previous
transmission or if the process of receiving a packet, when it will wait until this has finished. Also, it will not switch if a
preamble symbol having a signal quality above a minimum specified threshold has not been detected in the last 40μs
Both modes can be used at once and use the same ADO and ADE outputs to control the switch.
The JN516x provides an output (ADO) on DIO12 that is asserted on odd numbered retries and optionally its
complement (ADE) on DIO13, that can be used to control an antenna switch; this enables antenna diversity to be
implemented easily (see Figure 15 and Figure 16).
Antenna A
Antenna B
A
ADO (DIO[12])
SEL
ADE (DIO[13])
SELB
B
RF Switch: Single-Pole, Double-Throw (SPDT)
COM
Device RF Port
Figure 15: Simple Antenna Diversity Implementation using External RF Switch
ADE (DIO[13])
ADO (DIO[12])
TX Active
RX Active
1st TX-RX Cycle
2nd TX-RX Cycle (1st Retry)
Figure 16: Antenna Diversity ADO Signal for TX with Acknowledgement
If two DIO pins cannot be spared, DIO13 can be configured to be a normal DIO pin, and the inverse of ADO
generated with an inverter on the PCB.
28
JN-DS-JN516x v1.1 Production
© NXP Laboratories UK 2013