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I have a Arduino Nano clone working fine with the CH340 drivers. It has a CH340C on it.

I made a custom PCB. CH340 chips are hard to come by these days, so I opted for the CH340K, From the datasheet, seems like it should work similar to the CH340C and CH340G that are quite common.

My PCB has a footprint for both the CH340K and CH340C/CH340G (Yes, I'm aware I'm missing the load capacitors for the CH340G). CH340C/N/K/E and CH340B have built-in clocks without external crystal oscillator. So no need for a crystal.

After soldering on the CH340K and USB port, I plugged the device in, and I'm getting an error in Windows 10 Device Manager:

Unknown USB Device (Device Descriptor Request failed)

Windows has stopped this device because it has reported problems. (Code 43)

The USB set address request failed.

I've uninstalled and reinstalled the CH340 drivers several times. Tried to force the driver onto the device in device manager, and it didn't let me.

There's no short to ground or vcc.

Any help to get this recognized would be great! thanks!

CH340K Pinout

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PCB

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EdHayes3
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  • i think that i remember that the driver has `inf` and `ini` files associated with it ... they are text files ... some editing may be required ... google `CH340K inf` – jsotola Jul 16 '21 at 02:22
  • What is "the CH340 drivers"? When I google this, I get 967000 results. – Thomas Weller Jul 16 '21 at 05:04
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    Schematic? PCB design? Without those we can't help you – Majenko Jul 16 '21 at 08:39
  • A failure to read the device descriptor generally means that there is a hardware fault. It's not getting as far as even knowing that there is a real USB device attached, let alone working out which driver might fit the bill. You either have a fault in your design, a fault in your PCB layout or a fault in your soldering. – Majenko Jul 16 '21 at 09:46
  • Common problems include: * Accidentally swapping D+ and D-, * Shorting one of the data lines somewhere, * Incorrect crystal, * Incorrect crystal load capacitors, * Incorrect crystal layout (all three latter ones causing the wrong clock speed to be generated) – Majenko Jul 16 '21 at 09:48
  • Thanks all. I added some details to the post. Finding issues with CH340 K is impossible with all the other pages about the more ubiquitous C and G cluttering up search results. – EdHayes3 Jul 17 '21 at 05:11
  • That all looks ok to me except one thing: you have no decoupling capacitor on the V3 pin. The datasheet stipulates this as needing 100nF on it. – Majenko Jul 17 '21 at 08:57
  • Also, the DP trace is *very* close to the edge of your board. Have you confirmed continuity of that trace? You should leave at least 0.5mm gutter around the edge of your board to allow for tearing during routing or v-grooving. – Majenko Jul 17 '21 at 13:56
  • If I remember correctly, the official Windows driver does not support the latest revisions of the CH340. Can you tell us the error code that is shown in the device manager? – Sim Son Jul 20 '21 at 12:36
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    I checked the board, the traces are fine. Just updated post with the Windows error specifics. Maybe I should contact the manufacturer and see if there's an updated driver? I'm not expecting much support from them as the cheap manufacturer they are. – EdHayes3 Jul 21 '21 at 05:39
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    Majenko, was the 100nf capacitor for the win! Thought I didn't need it since I wasn't going to be using the LDO output for anything else on the board. Want to make the official answer? – EdHayes3 Jul 21 '21 at 16:21

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Needed a 100nf capacitor on the v3 pin, per Majenko's suggestion, and per datasheet.

I thought this was only needed if you were going to use the 3.3v output for other purposes. I was wrong!

Same requirement for the CH340C!

EdHayes3
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on you Pcb the Footprint is not correct! UD+ is on GND, UD- is on UD+ and GND is on UD- . The CH340K has a differnt Footprint.

H.S.
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