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problem with cc1101 initialization - EMC certification

michele mazzacchi
Prodigy 100 points
Other Parts Discussed in Thread: CC1101

I have an emission EMC problem with the cc1101. I have an hardware problem and a fw problem. Now i would to solve the fw problem: in certification i have to transmitt a 40msec of packet information every 200msec. With the cc1101 there are a lot of possibility to make this: i choose to start from an idle state and transmitt the packet with autocalibration and FSTXON every wake up. The problem is that i see various spourios before the 868MHZ (600Mhz-865Mhz of 10dBm). With the smart RF demo coupled with the TI radio or with my hw radio i don't see those spourious.

I tried to use the autocalibration every 4th wakeup from idle, or didn't use the idle state but the problem remains (every 4th the problem is minor, but the frquency was changed )

1) What is the sequence used from SMARTRF in the packet trasmitt? Is there available a source code?

2) Is it possibile that during the autocalibration or during FSTXON the cc1101 emitt this unwanted "spourious". The spourious are not an armonic of the 26MHZ.


Best regards
Michele Mazzacchi

  • 0
    TI__Guru**** 317180 points

    Could you please specify which item in which standard you have an issue with?

  • 0 in reply to TER
    Prodigy 100 points

    Thanks, we use the EN300 220-2 v.2.3.1 and we have a problem with the spurious in the frequency below.

    I have to solve the initialization of the cc1101, because i have to transmit in packet modality and i have to understand the flow to initialize correctly the chip cc1101.

    thi is the report of the spurious:

    Frequency  MaxPeak Height Polarization Azimuth Margin Limit (dBm)

    494.023750 -54.9 100.0 V 269.0 0.90 -54.00
    511.378750 -57.4 252.0 V 269.0 3.40 -54.00
    528.685000 -51.7 198.0 V 269.0 -2.30 -54.00
    546.040000 -52.7 147.0 V 269.0 -1.30 -54.00
    580.701250 -55.9 150.0 V 2.0 1.90 -54.00
    598.056250 -55.9 202.0 V 180.0 1.90 -54.00
    615.313750 -54.8 150.0 V 180.0 0.80 -54.00
    632.668750 -49.6 100.0 V 269.0 -4.40 -54.00
    667.330000 -48.8 147.0 V 269.0 -5.20 -54.00
    719.346250 -54.1 100.0 V 2.0 0.00 -54.00
    860.575000 -50.4 252.0 V 269.0 -3.60 -54.00
    868.375000 -1.2 252.0 V 269.0 -34.80 -36.00

    best regards Michele Mazzacchi

  • 0 in reply to michele mazzacchi
    TI__Guru**** 317180 points

    EN300 220-2 v.2.3.1 does not require the test setup to send packets. For all TX tests cont. TX can be used except for transient power which is very easy to pass due to step2 (described in section 7.5.2 in the standard)

  • 0 in reply to TER
    Prodigy 100 points

    In my application i have to use the packet modality every 15minutes, The certificator asked me to reply the real application but transmit frequently (every 200msec.) I can't change the modality in continuos mode.

    So i have to solve the CC1101 the initialization problem and understand if the autocalibration (in wake up from idle) or ON frequency syntesizer can create spurios and how to avoid those.

    Best regards

    Michele Mazzacchi

  • 0 in reply to michele mazzacchi
    TI__Guru**** 317180 points

    Note that the certifying test houses from time to time say wrong things. I'm trying to make it easier for you to pass in the end and also doing the test as stated in the standard. Which section of EN300 220-2 v.2.3.1 does the certificator tell you that you need to reply real application?  

  • 0 in reply to TER
    Prodigy 100 points

    Ok thanks,  but outside certification i would understand the advent of those spurious with my hw packet transmit, because those spurious there aren't with the TI packet application.

    Could you help me if you know or if you could tell me the TI SMART RF source?

    Your sincerely

    Michele Mazzacchi

  • 0 in reply to michele mazzacchi
    TI__Guru**** 317180 points

    We don't share the code for SmartRF Studio. Do you get the same with one of the code examples online?

    Please check that the PA ramping (PATable7-0) is set correctly since this will influence the spurious when sending packets.

  • 0 in reply to TER
    Prodigy 100 points

    Thanks,

    i write 0x50 on the PATABLE as the SMART RF.

    I'm sorry for the SMART RF code source, could you suggest me a link for the packet from the IDLE STATE transmit?

    your sincerely

    Michele Mazzacchi

  • 0 in reply to michele mazzacchi
    TI__Guru**** 317180 points

    Have you tried to turn the PA ramping on?

    In SmartRF Studio I think we only fill up the FIFO and then issue STX.

  • 0 in reply to TER
    Prodigy 100 points

    I see the light, but i'm asking your support for any last questions, i hope. I trasmit every 200msec and i try to make the aucalibration and FSTXON only every 1 minutes; every 200msec i wake up from idle with STX and trasmitt the packet with the autocalib disable. The spurios is minor as value. Could you suggest other?    

    The PA is disable, how to enable?

    your sincerely

    Michele Mazzacchi

  • 0 in reply to michele mazzacchi
    TI__Guru**** 317180 points

    Not sure if I understand the first part of the question.

    For PA ramping, see the vales suggested by SmartRF Studio for PAtable7-0. In Studio it is possible to turn on/ off the PA ramping with a tick box in the control panel. See chapter 25, page 60 in the UserGuide for more information.

  • 0 in reply to TER
    Prodigy 100 points

    Sorry for my english, about the first first part of question i would to tell you that i have to transmit a packet without the autocalibration, and i would ask you if my idea is correctly. I have to send every 200msec. so i wakeup from idle state with STX command, in this case i disable the autocalibration and i 'll return in the idle state after the packet transmitted.  Every 1 minutes i wakeup with the autocalibration and the strobe SFTXON and then i return in the idle state. Without autocalibration and the SFTXON the spurious is minor as value, is it possibile ?

    Could you suggest other tecnhiques to improve the spurious?

    Could you give me an example to enable PA RAMPING?

    your sincerely

    Michele Mazzacchi