I've been trying to get a UART made with an FTDI chip - this one to be specific: https://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT230X.pdf

I've wired it up to be USB bus powered, as per section 6.1 of the manual above. However, when I plug into Linux I get this:

[20552.129143] usb 2-7: new full-speed USB device number 11 using xhci_hcd
[20552.129267] usb 2-7: Device not responding to setup address.
[20552.341260] usb 2-7: Device not responding to setup address.
[20552.549140] usb 2-7: device not accepting address 11, error -71
[20552.549178] usb usb2-port7: unable to enumerate USB device

I'm not sure where I've gone wrong. Here is how I've setup the FTDI chip:

enter image description here

And here is the USB end:

enter image description here

Does anyone have any ideas at all please? I'm wondering if the reset pin might be the cause, or possibly something with the 5 and 3.3V going on, but as far as I can see, this matches the datasheet exactly. Cheers! Ben

  • 2
    \$\begingroup\$ C29 is in the wrong place \$\endgroup\$
    – jsotola
    Commented Jun 15, 2021 at 16:11
  • \$\begingroup\$ Good spot! Thanks! \$\endgroup\$
    – Oni
    Commented Jun 15, 2021 at 16:42

1 Answer 1


Try removing C28 and C29. I could only get mine working properly without those values.

  • 1
    \$\begingroup\$ Fantastic! Thanks! This seems to have worked so far. I get a USB serial COM port in Windows (have not yet tested with Linux). This seems to be an error in the datasheet then? Surely that can't be the case? Still - it does work grand! Thanks! \$\endgroup\$
    – Oni
    Commented Jun 15, 2021 at 16:33
  • \$\begingroup\$ How sure you are you had 47 pF capacitors? \$\endgroup\$
    – Justme
    Commented Jun 15, 2021 at 19:05
  • \$\begingroup\$ Now you've said it, I'd better check though I'm pretty sure they were correct. As pointed out above, one is slightly wrong in the schematic though I'm not sure it affects things too much \$\endgroup\$
    – Oni
    Commented Jun 15, 2021 at 20:17

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