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CC1101 register values changing

Andy Potter
Prodigy 20 points

Hi

I have a pair of SMARTRF04EB dev boards with CC1011 434MHz EM modules.

I've used the SMARTRF Studio PC application to select a set of register values that match our requirements and selected the 'RF Device Commands' tab on the App so that I can manually control the device into various working States on the Rx end. We are ultimately trying to get it to work in WOR mode.

I am finding that if I press the Refresh button repeatedly (bottom right hand side of the App) I find that FOCCFG, FSCTRL1, IOCFG0 and FREQ1 registers change value from the initial setup for some reason - for example FREQ1 changes from 0xb1 to 0xb9. In this instance, the carrier frequency will change from 433.999MHz to 434.812MHz. We will not be able to work with this sort of shift in frequency and do not understand why its been forced to change. If I continue to press the Refresh button then the register values continue to change almost at random.

I also find that WOREVT1 and WOREVT0 change from 0x1830 to 0x1c38 - in this case, the fact we are using WOR mode, means this will cause it to fail.

I'd like to understand why this is happening please? We seem unable to get a stable environment to work with at the moment. 

Thanks, Andy

  • 0
    TI__Expert 4470 points

    Hi Andy,

    I would like to try reproduce the behaviour you are seeing. Could you please describe the exact steps to trigger this?

    I am trying to press 'Refresh' repeatedly, but i do not see the described behaviour in my setup. Are you doing any action between each register refresh?

    Just for info, pressing the 'refresh' button causes all register values in register view to be updated with the current values on the device (i.e. reads register values from the device, and updates the view)

    Bjørn

  • 0 in reply to Bjørn
    Prodigy 20 points

    Hi Bjørn

    Thanks for your reply.

    I think I've traced the cause of the problem.

    I had GDO1 set to be an output to toggle when a valid sync word was received (I had IOCFG1 set to 0x06). Looking at the schematic for the CC1101EM module, I can see that IOCFG1 doubles up as the SPI Data Out pin. So I suspect that this would cause a contention on that pin that would certainly cause comms errors to occur. Since changing my code to make that pin high impedance the problem described above has disappeared.

    I'll email again if it returns!

    Many thanks, Andy