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CC2591 + CC8531 issue with control signals (EN,PAEN)

adamhajduch
Prodigy 20 points
Other Parts Discussed in Thread: CC8531, CC2591, CC2590

Hello

I have a issue with control signals from CC8531. I make my own design of the board. Here is schematic. CC2591 and CC8531 is connect following the reference design. 

In PPW Configurator I set in radio range extender- CC2591 HMG. 
Than i measure logical states on EN and PAEN signals:

On master device in: standby mode: EN=0 , PAEN=0
                                 pairing mode:   EN=0 , PAEN=0

On slave device in: standby mode: EN=1 , PAEN=0
                               pairing mode:   EN=1 , PAEN=0

Of course the devices can not pair together.

When I set in range extender option- none, than the devices are paired together, but the connection is very weak and crashing down .

Why are the control signals incorrect ?

Thanks for answers.

  • 0
    TI__Mastermind 21125 points

    Hi Adam, 

    This is a tough one. The xLNAEN and xPAEN out of the CC85xx is hardware controlled and should toggle "rapidly" when range extender is set to something different than "none" in the configurator. 

    As a debug step, is it possible for you to remove the inductors on these two pins and look at the pins on the CC85xx side with a logic analyzer? 

    Setting the range extender to "none" will severely affect the link robustness as the CC2591 will act as a attenuator.

    On a different topic. I would not recommend going with the CC2591 as it is difficult to get a stable and good layout for this device:
    - The CC2591 is known to easily oscillate and making a robust design is difficult
    - The extra output power of the CC2591 vs. the pin-to-pin compatible CC2590 will add power pulling effects on the supply and ground planes. This can be picked up by analog circuitry (ADC/DACs) and become audible (and annoyingly so in the ~400 Hz range)
    - Only FCC (US regulations) allows for additional output power that only the CC2591 can deliver. For world wide usage the CC2590 is the right device
    - The CC85xx link is not only limited by the link budget, but also multi-path effects (more-so than other narrow band systems) and in practice the range should not differ that much between using CC2590 vs. the CC2591

    At least some food for thought, but the original problem needs to be resolved prior to taking the next step off course. 

    Regards, 
    Kjetil

  • 0 in reply to Kjetil
    Prodigy 20 points

    Thanks you so much Kjetil. It is works very good with CC2590. The control signals is now right.