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>=2Mbps GFSK Transceiver with prop. packet format

John Malsbury
Prodigy 70 points
Other Parts Discussed in Thread: CC2640

I am looking for a solution that will me to implement a custom packet format that will include a block code instead of a CRC.  Are there any chips that support the following:

  1. Buffering/output of received frames even if they fail CRC?
  2. Output of clock/data from demodulator so I can do framesync detect and frame processor in my MCU>

etc.


I like the CC2640, but it doesn't seem possible to bypass the frame processing in the chip.  Any input here would be appreciated. 

For comparison, I'm looking for something like the SPORT mode of ADF7242.

  • 0
    TI__Genius 9705 points
    Hello John,

    2mbps data rate using 2GFSK modulation is supported on CC26xx and CC254x families of devices. On CC2640, it is possible to disable CRC check and receive all packets for post-processing on CM3. However, routing of clock and data from demodulator at 2mbps is not supported currently. Is there a reason you are planning to do this on an external MCU vs using CC26xx processor?

    Regards,
  • 0 in reply to SVS
    Prodigy 70 points

    We have an interest in implementing  FEC and some interleaving to protect the payload.

    How does the CC2640 know how many bytes to read in the packet?  Can you set it to always buffer X number of packets after seeing a sync word, or will it rely on  the possibly corrupted/unprotected length field? 

  • 0 in reply to John Malsbury
    Prodigy 70 points
    there was a type:

    an you set it to always buffer X number of packets => an you set it to always buffer X number of ***BYTES***
  • 0 in reply to John Malsbury
    Prodigy 70 points
    Also, one clarification... If we use the CC2640, we *would* use in the internal M3. We just need more control over the packet format, that's all.
  • 0 in reply to John Malsbury
    TI__Genius 9705 points

    Hello John, 

    There is some flexibility available with packet format, some with the command options and more with overrides. If you can tell us what changes you are looking at from the default format, we can confirm if it is possible to do. 

    With regards to packet length, there are couple of options at 2mbps data rate:

    1. Using variable length packet option where the length byte is appended before the payload and receiver knows to look for this information.

    2. Fixed packet length option where the packet length is not appended in the transmitted packet. Receiver expects packet length to be as specified in maxPktLen field in the receive command. 

    If you are not using the HS mode (for data rate less than 500kbps GFSK), there is also an option to set up unlimited length packet and implement partial receive. All these options are explained in the technical reference manual. If you disable CRC, packets received can be retrieved from RX Queue and FEC can be added on the application code. 

    Hope this helps. 

    Regards,