nRF52840 USB Interface Circuit

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In my design, I choose to use the circuit suggested in Config no.5, but the USB interface is not effectively identified in the actual test. Through the test, the power supply of 5.0V can be measured on the VBUS pin (referred to as the USB interface), but there is no voltage measured on the DECUSB pin. Through the block diagram provided in the datasheet, I have eliminated the SMT quality problem by X-RAY, is there any problem that I did not consider during the debugging process or is there a problem with my schematic diagram?

PS：

1.At present, the board can burn the program normally, and the peripherals can also be controlled.

2.USB Demo selected the official course, the routine can run normally on the DK board .

Nordic Config no.5 Circuit

My design

Chip X-RAY

[Priyanka]

Hi,

Your schematic seems to follow the reference design. The crystal capacitor values are different, but as long as you have verified this with your crystal frequencies, it should be fine.

 General PCB design guidelines for nRF52 series 

-Priyanka 

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Hi Priyanka
Crystal Capactior value is different  from the actual value, in my design Crystal CL is 6pF Ccap = 2*6pF - 3pF =9pF Is this calculation correct？ This board other peripherals are working normally， Only USB interface not work.

Although it is working at present, I still want to confirm whether my calculation is correct.

Thanks!

[Priyanka]

Could you tell me what you measure at the VBUS pin?

-Priyanka

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 In Nordic nRF52840 VBUS pin's capacitor measure value is 5.0V，is same as nRF52840DK, But in DECUSB pin valeu is 0V, in DK board this pin‘s value is 3.1V.