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CC2520+CC2591 On a single board

Mike3625
Prodigy 50 points
Other Parts Discussed in Thread: CC2591, MSP430F2618, CC2520, CC2430

I am developing a board that uses the MSP430F2618, the CC2520, and the CC2591. I am using Zstack 2.1.0 and have been copying the connection of the MSP430 to the CC2520 from the CC2520DK.

From some comments in Zstack(mac_dualchip.c) , I see the following connections from the CC2520 to the CC2591:

   * PA/LNA register configurations. Note that the settings for GPIOCTRL4 and
   * GPIOCTRL5 are not documented in the datasheet.
   *
   * GPIOCTRL3    = 0x7F (HGM per macRxGain)
   * GPIOCTRL4    = 0x46 (EN set to lna_pd[1] inverted)
   * GPIOCTRL5    = 0x47 (PAEN set to pa_pd inverted)
   * GPIOPOLARITY = 0x0F (invert GPIO4 and GPIO5)

Are GPIO3,4,5 still left connected to the MSP430?

 

I plan to put an RF switch in the circuit to allow bypassing of the CC2591. This means that the differential output of the CC2520 will get converted to a 50 ohm single ended signal. It will then go through an RF switch. One output will go to a balun (the one in the reference design for the CC2591) at the input of the CC2591 and one end will go to an SMA connector.

The reference designs for the CC2520 and the CC2591 both contain trace inductors and are done on boards with two different layer thicknesses (signal to ground). The datasheets for the two parts recommend using the reference designs but this is not possible due to the two different board thicknesses. I have calculated the trace inductor values on the CC2520 board to be values that are avaiable in discrete packages (1.7, 2.2, 2.4nH). Very high-Q versions are avaiable from Coilcraft. The trace inductors on the CC2591 have a very low value and are not available in discrete packages. Should I follow the reference design from the CC2591 (using the trace inductors) and use the discrete inductors for the CC2520?

 

If I do not put the bypass switch for the CC2591 in the circuit, the CC2520 will be directly connected to the CC2591. Page 11 of the CC2591 datasheet shows the connection of the two parts. Components C1, C21, C41,L21, L41 are listed in the design and attahced to RF_N and RF_P. I can not find the values for these components in any publicly available documentation. What are they?

 

 

  • 0
    TI__Prodigy 140 points

    I know we have some people working on a CC2520+CC2591 reference design as we speak. That will probably answer most of your questions (my guess is the reason the component values for C1, C21 etc aren't listed anywhere is because the CC2520+CC2591 reference design simply isn't finished yet).

    With regards to the which reference design you should follow: I suggest you use the CC2591 PCB thickness and follow that reference design (it's probably the most sensitive of the two parts). Keep in mind that when you change the RF layout of the CC2520 (which you would have to do), you will also change the performance. The most likely change you will see is a worsening in signal quality (increased spurious emissions, spectral regrowth etc), which will get worse at lower temperatures. You will have to pay close attention to signal quality and spurious emissions depending on what regulations you have to pass. If you're looking for 802.15.4/ZigBee compliance, keep in mind that there is an absolute EVM requirement (a measure of signal quality), and that this requires specialized instruments to measure. I suggest you contact our support department for more information about how to create a custom CC2520+CC2591 board.

  • 0 in reply to arne3009
    Prodigy 50 points

    Thanks arne. How do I get in touch with the support department. I used the online form for tech support last week and did not get a response.

     

    Any idea what to do with GPIO3,4,5? 

  • 0 in reply to Mike3625
    TI__Mastermind 19575 points

    Hi Mike, 

    I think it is great you use the forum to post questions. With this approach everyone who are interested in the same topic can benefit from your questions and 
    ideas.

    Take a look at the follwoing thread for some hints on the GPIO pins connection.

    https://community.ti.com/forums/t/289.aspx

    LPWRocks 

  • 0 in reply to arne3009
    Prodigy 110 points

    Hi,

    I am working on a near identical design - using an MSP430F54xx + CC2520 + CC2591. I would like to use an RF switch to be able to use SW to switch between a trace inverted-F antenna and an external connector - for performance testing purposes. But first, I'm trying to layout the basic CC2520 + CC2591 schematic and PCB layout.

    Has the CC2520 + CC2591 reference design been released, yet? So far I'm trying to piece together an appropriate schematic from the two separate products' datasheets and ApNotes. I see there is a new CC2520+CC2591EMK Evaulation Module Kit (http://focus.ti.com/docs/toolsw/folders/print/cc2520-cc2591emk.html) available. But, I did not see any easily available documentation on the schematic or reference design for this product. Does anybody have a link to the reference design for this board?

    Also: Mike, would you be willing to share your schematic for how you are designing the RF switch to effectively enable/disable the CC2591?

     

    thanks

    Michael

  • 0 in reply to mgcorr
    Prodigy 135 points

    Hi,

    I am also interested in trying the CC2520+CC2591EMK Evaluation Module Kit, however the order button on the product information page doesn't work yet.
    When will that kit be available to order?

    Thanks,
    (another) Michael

     

  • 0 in reply to michi
    TI__Mastermind 19575 points

     

    michi,

    Check out the new released application notes:

    • AN066: TI-MAC modifications for using CC2591 PA/LNA with MSP430F2618+CC2520 (swra230.htm, 8 KB)
      15 Sep 2008 Abstract
    • AN065: Using CC2591 RF Front End with CC2520 (swra229.htm, 8 KB)
      12 Sep 2008 Abstract

    LPRF Rocks the World

  • 0 in reply to michi
    Prodigy 135 points

    To answer my own question: I just called the product information center and apparently you can order the CC2520+CC2591EMK Evaluation Module Kit now and it is expected to ship on October 20.

     

  • 0 in reply to michi
    TI__Mastermind 19575 points

    Yes, that is right.

    Here is the reference design.

    http://focus.ti.com/docs/toolsw/folders/print/cc2520-cc2591em_rd.html

    LPRF Rocks the World

  • 0 in reply to Morten Braathen
    Intellectual 740 points

    Does TI have any plans to transition these development kits into OEM parts (pre-FCC Certified)?   Is any 3rd party doing so?  Given that the reference designs are so stingent and many people are essential recreating the same chip combinations and seperately certifying, it would be very advantageous for developers to have OEM boards to eliminate these tasks.

  • 0 in reply to RFCE
    TI__Mastermind 18780 points

    Hi,

    TI makes reference designs that are tested for compliance, but no precertified modules. But we totally agree that it is advantageous with such modules, so we do use 3rd parties. I know Radiocraft (http://www.radiocrafts.com) is currently working on a precertified module with CC2430 and CC2591, so I suggest that you contact them.

    Charlie