NXP Semiconductors MKW01Z128, Reference Manual, Page: 102 / 884

Transceiver Digital Control and Communications
MKW01xxRM Reference Manual, Rev. 3, 04/2016
Freescale Semiconductor, Inc. 7-15
If the address filtering is expected then AddressFiltering must be enabled on the transmitter side as well
to prevent address byte to be encrypted.
Crc check being performed on encrypted data, CrcOk interrupt will occur "decryption time" before
PayloadReady interrupt.
7.5.6 Handling Large Packets
When Payload length exceeds FIFO size (66 bytes) whether in fixed, variable or unlimited length packet
format, in addition to
PacketSent in TX and PayloadReady or CrcOk in RX, the FIFO interrupts/flags can
be used as described below:
• For TX:
— FIFO can be prefilled in Sleep/Standby but must be refilled "on-the-fly" during TX with the
rest of the payload.
1. Prefill FIFO (in Sleep/Standby first or directly in TX mode) until FifoThreshold or FifoFull is set
2. In TX, wait for FifoThreshold or FifoNotEmpty to be cleared (i.e. FIFO is nearly empty)
3. Write bytes into the FIFO until FifoThreshold or FifoFull is set.
4. Continue to step 2 until the entire message has been written to the FIFO ( PacketSent will fire when
the last bit of the packet has been sent).
• For RX:
— FIFO must be unfilled "on-the-fly" during RX to prevent FIFO overrun.
1. Start reading bytes from the FIFO when FifoNotEmpty or FifoThreshold becomes set.
2. Suspend reading from the FIFO if FifoNotEmpty clears before all bytes of the message have been
read.
3. Continue to step 1 until PayloadReady fires.
4. Read all remaining bytes from the FIFO either in RX or Sleep/Standby mode.
NOTE
AES encryption is not feasible on large packets, since all Payload bytes need
to be in the FIFO at the same time to perform encryption.
7.5.7 Packet Filtering
MKW01Z128's packet handler offers several mechanisms for packet filtering, ensuring that only useful
packets are made available to the MCU, reducing significantly system power consumption and software
complexity.
7.5.7.1 Sync Word Based
Sync word filtering/recognition is used for identifying the start of the payload and also for network
identification. As previously described, the Sync word recognition block is configured (size, error
tolerance, value) in
RegSyncValue registers. This information is used, both for appending Sync word in
TX, and filtering packets in RX.