What happens if I write "0" into PREAMBLE_LEN register of ADF7023?


I have this question because I have to work on a receiver that is going to receive packets from the ADF7023 and the product I have to receive from is already finished and based on this chip.

The people I'm talking to to get support from this product say that there is no preamble being sent, that everything starts from the sync word. On the other hand I read in the datasheet:

The preamble is a mandatory part of the packet that is automatically
added by the communications processor when
transmitting a packet and removed after receiving a packet.
The preamble is a 0x55 sequence, with a programmable
length between 1 byte and 256 bytes

But I find that the register can be written from 0 to 0xFF since is a 8 bit register and the documentation says:

Length of preamble in bytes. Example: a value of decimal 3 results in a preamble of
24 bits.

So, following this logic that tells me that you can actually write a 0 in the register because there is no explicit place that says you can't, but I don't know what is going to happen. So if a value of 3 means 24 (8 x 3) and a value of 1 would be 8, then a value of 0 means what?

I get confused with this and the fact that this person is telling me that there is no preamble in the packet.

Is this possible? Or I will have a preamble of 8 bits if I write "0" and "1"?


  • 0
    •  Analog Employees 
    on May 1, 2017 8:35 PM

    It should read 1 to 255 bytes of preamble. A value of 0x01 will mean 1 byte of preamble is transmitted. I'm not sure what would happen if a value of 0 is used but you could check in on an RF scope or perhaps the whether the  transmission length differs in zero span mode on a spectrum analyzer. They could be using the part in SPORT mode rather than packet mode on the transmit side where they bypass the transmit packet handler to transmit zero preamble.

    On the transmit side the PA will ramp up during preamble but the main requirement to transmit preamble is to allow the receiver to settle (AFC, AGC, CDR) prior to payload.

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:40 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin