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CC1110-CC1111: How to decode data with only 9 bits of sync header

Part Number: CC1110-CC1111
Other Parts Discussed in Thread: CC1101

Hi Team,

 

My customer wants to decode data with only 9 bits of sync header in RX.

Frequecy: 315MHz, Baudrate 10K   FSK mode

In DMA RX mode ,there are only two options for synchronization:16bit and 32bit.

Now there is a TX with only 9 bits in the sync header,there is no way to continue to use DMA to receive,.

Can it use only 9 bits synchronization, how to configure?

Could you help to check it?

Regards,

Kevin

 

  • hi Kevin

    CC1110 support a 16 bits sync word (which can be repeated to be a 32 bits sync word). This has nothing to with the DMA.

    If the packet you want to receive with the CC1110 only transit a 9 bits long sync word, you will need to use part of the preamble sent by the transmitter as sync:

    Example:

    Preamble: 0x55555555 (4 bytes)

    Sync: xxxxxxxxxb (9 bits)

    Sync used by CC1110 in receive: 1010101xxxxxxxxxb (16 bits)

    BR

    Siri

  • Hi

    I think that's the question I asked.
    Let me add some details: in fact, the data format we want to receive is not defined by us and cannot be modified.


    The incoming data format is:

    0b0000 0011 1111 001  + 66bits data + 0b10

    I hope you can understand what I mean. After all, we are not good at communicating in English

  • I am not understanding your last e-mail. I have already answered that the CC1110 needs minimum 16 bits sync word word, and if you do not have 16 bits sync, you need to add the preamble.

    You said there was 9 bits sync, but you are showing 15 bits:

    0b0000 0011 1111 001  + 66bits data + 0b10

    If there are only 15 bits before the data is coming, you will not be able to use the packet features of the CC1110, since it cannot look for sync word less than 16 bits (and it also needs several bytes of preamble BEFORE the sync word).

    The only option you have is to see if you can receive the data in transparent mode:

    Siri

  • Hi Siri,

    When the customer uses FSK modulation signal reception, configure IOCFG1 = 0x0D.

    and the transmitter does not send data, but at this time the waveform of the P1.6 is as follow:

    Codes setting:

    He thinks TX does not send, there should not be so much data on the pin P1.6 .

    If he wants the waveform output on P1.6 only when the transmitter is sending data

    How to do ?

    Regards,

    Kevin

  • There is always noise on the air that you will pick up so what you see is normal.

    BR

    Siri

  • Well , Besides using 'MDMCFG4.CHANBW_E'&'MDMCFG4.CHANBW_M' to change channel filter bandwidths, is there any other way to reduce noise? We really need more advice.

  • You will not be able to "remove" the noise that is on the air. What you need to check is that you are able to see the data you actually are transmitting.

    The radio is not designed to do transparent mode and you have not much preamble/sync for the radio to settle on/sync on before your data, so not sure how good the results will be.

    I do not have a CC1101 to test with, but I did a test with CC1101 (same radio)  in transparent mode.

    My transmitter is set up to send 0xAA, 0xAA, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0xAA

    As you can see between the cursors, you will find the transmitted data even if you pick up noise before and after the packet. In transparent mode, you need to make an algorithm in SW that will look for you data, the radio will not do it for you (it will only provide the raw data from the air).

    Siri

  • Dear Siri

    Thank you very much, we now figure out where the problem is.

    According to the experience of "OOK", we expect to see either a straight line or data with an oscilloscope.

    When we see the noise that has always existed, we think something must be wrong, and we have been trying to reduce the noise to make it a straight line.

    Later, we will try to let the software find data in the noise, which should not be difficult.

    Please allow us to express our sincere thanks again!

    Frederc  Wang

  • Glad to hear you are making progress :-)

    BR

    Siri