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nrf52832 ble problem

Navdeep

I have designed nrf52832 customized board with tace antenna antenna and every pin of the controller is connected to the male headers present on both side of the boards. I havent used lpkf , so I changed the sdkconfig.h file to use internal RC but it wasnt working. By mistake , the P0.07 pin gets connected to Vcc and the led start blinking i.e. the bluetooth is advertising. Now ble is working fine but everytime I have to connect this P0.07 with 3.3v or also with little variation on that pin (like when I Just touch that pin with my fingers). I want to kmow that P0.07 is just an I/o pin , so why this behaviour? DOes it mean there is problem in my layout design.

There is no problem in the code as I'm using the standard code of ble of nrf52 dk by changing the sdkconfig.h as we dont have lpkf

  • 0

    Ohk I will post you the schematic and layout soon. But a quick question,as you have said, the capacitor size matters!!.

     I have used various 0201 capacitors instead of 0402 and 0603 but with the same specs given in nrf datasheet. Does that honna make any difference?

  • 0 in reply to Navdeep

    I should have said “capacitance value”. For the logic portion of the chip, the physical size is not too important. But since the SRF ( series (or self) resonant frequency ) is strongly correlated with the value, it is best to use a combination of large and small value caps as they do in the reference design. 

    On the RF the physical size of the cap influences the size of the pads and microstrips that should be used. This is more a method of controlling parasitic reactances on RF.

    Our own designs make use of 0201 parts for much of the logic and all of the RF. Only bulk storage capacitance is made up of 0402 and 0805s. We utilize 0805s since our main product is a coin cell powered device. Thus we need a lot of local capacitance.

    happy to review your design and provide feedback.

  • 0 in reply to AmbystomaLabs

    Hi, Please find the below attachment. I would really appreciate if you can sort out the issue.

    In conclusion, we have to short any pin( P0.07 to P0.10) with 3.3v , and then nrf start advertising ,not without that. SO please check the attachments and let me know where we are doing wrong.

    Also, as you have mentioned that your product is cell based, and for that you are using 0805 package. In our case, we are also going to give power through button cell ( but now, we are just powering it through constant 3v supply from another board), so please explain me properly the significance of 0805 in this case.

    I would really appreciate.

  • 0 in reply to Navdeep

    Please post the ground plane layer too.

    On your question regarding the 0805 caps, coin cell batteries have very poor current sourcing capabilities. In my lab, I simulate them by putting 200ohms in series with the bench supply.

    I talk about it a lot on this site.  You should read the Texas Instruments white paper on the subject and also look at a coin cell spec.

    Using a coin cell and no external current consuming circuitry, the best you can expect is about 2% duty cycle assuming you put about 22uF of MLC caps on the board. Thus why I use 0805 parts.  Our design actually has an external PA uses much more power.  So we place about 100uF of MLC caps. 2x 47uF 0805 and 2x 2.2uF 0402.

    Here are some recent devzone comments on it: https://devzone.nordicsemi.com/search?q=ambystomalabs%20ti%20coin%20cell

  • 0 in reply to AmbystomaLabs

    Thanku so much, I will go through the above link. and please find the following attachments-

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