nRF52840 USB Interface Circuit

RE: nRF52840 USB Interface Circuit

Search — Tue, 23 Jul 2024 12:35:57 GMT

Good news. The system is working！I'll consult you later if I have any questions.
Thanks a lot~

-Search

RE: nRF52840 USB Interface Circuit

Priyanka — Mon, 22 Jul 2024 13:26:37 GMT

Hi,

Could you specify as to what troubles you face with the nRF21540?

-Priyanka

RE: nRF52840 USB Interface Circuit

Search — Sat, 20 Jul 2024 07:04:58 GMT

Hi Priuamka

I think I have found the problem. In the first PCB, there may be a welding quality problem. In the second PCB, it was confirmed by X-ray that the welding was reliable. After modifying the code, it was found that the external 32.768Khz crystal oscillator did not work well. Later I welded a PCB again to verify this conjecture.

At the same time, it is regrettable to find that my nRF21540 cannot work normally, I wonder if you can provide technical support for this?

- Search

RE: nRF52840 USB Interface Circuit

Priyanka — Fri, 19 Jul 2024 11:47:31 GMT

Hi,

How much is the USB supply? If you supply 5V USB power, then you should be able to see 3V at the DECUSB.

Did you check the board for any hardware damages like shorts, soldering problems etc?

-Priyanka

RE: nRF52840 USB Interface Circuit

Search — Thu, 18 Jul 2024 11:26:56 GMT

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.

RE: nRF52840 USB Interface Circuit

Priyanka — Thu, 18 Jul 2024 11:22:56 GMT

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

-Priyanka

RE: nRF52840 USB Interface Circuit

Search — Thu, 18 Jul 2024 09:57:53 GMT

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!

RE: nRF52840 USB Interface Circuit

Priyanka — Thu, 18 Jul 2024 09:45:51 GMT

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