RF64 Datasheet, PDF (51/76 Pages) List of Unclassifed Manufacturers – ADVANCED COMMUNICATIONS & SENSING

ADVANCED COMMUNICATIONS & SENSING
Optional DC free data coding
CRC checksum calculation
RF64
Preamble
1 to 4 bytes
Sync Word
1 to 4 bytes
Length
byte
Address
Message
byte
0 to (FIFO size - 1) bytes
CRC
2-bytes
Payload/FIFO
Fields added by the packet handler in Tx and processed and removed in Rx
Optional User provided fields which are part of the payload
Message part of the payload
Figure 44: Variable Length Packet Format
5.5.3. Tx Processing
In Tx mode the packet handler dynamically builds the packet by performing the following operations on the payload
available in the FIFO:
 Add a programmable number of preamble bytes
 Add a programmable Sync word
 Optionally calculating CRC over complete payload field (optional length byte + optional address byte +
message) and appending the 2 bytes checksum.
 Optional DC-free encoding of the data (Manchester or whitening).
Only the payload (including optional address and length fields) is to be provided by the user in the FIFO.
Assuming that the chip is already in Tx mode then, depending on IRQParam_Tx_start_irq_0 bit, packet
transmission (starting with programmed preamble) will start either after the first byte is written into the FIFO
(Tx_start_irq_0=1) or after the number of bytes written reaches the user defined threshold (Tx_start_irq_0=0). The
FIFO can also be fully or partially filled in Stby mode via PKTParam_Fifo_stby_access. In this case, the start
condition will only be checked when entering Tx mode.
At the end of the transmission (Tx_done = 1), the user must explicitly exit Tx mode if required. (e.g. back to Stby)
Note that while in Tx mode, before and after actual packet transmission (not enough bytes or Tx_done), additional
preamble bytes are automatically sent to the modulator. When the start condition is met, the current additional
preamble byte is completely sent before the transmission of the next packet (i.e. programmed preamble) is started.
5.5.4. Rx Processing
In Rx mode the packet handler extracts the user payload to the FIFO by performing the following operations:
 Receiving the preamble and stripping it off.
 Detecting the Sync word and stripping it off.
 Optional DC-free decoding of data.
 Optionally checking the address byte.
 Optionally checking CRC and reflecting the result on CRC_status bit and CRC_OK IRQ source.
Only the payload (including optional address and length fields) is made available in the FIFO.
Payload_ready and CRC_OK interrupts (the latter only if CRC is enabled) can be generated to indicate the end of
the packet reception.
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