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STM32F103VET6 and CH340G

gazy98

New Member
I have a problem with my PCB. I recieved it a few days ago and it is
already completly presoldered. If i connect it via USB-TYPE B to my pc
it is showing me nothing in device menager.... The CH340G should be
visible to be able to programm it via usb....
If i connect an ARDUINO MEGA with ch340 it is visible so there shouldnt be an driver issue. But i still made updates to the drivers a few times just to be safe.....

If i connect it via micro-usb unknown device is popping up. But that
does not help me :).

I have added the schematic. Hope someone can help me.
 

Attachments

Visitor

Active Member
If memory serves, I have made the the same mistake. I believe the CH340 V3 pin needs a cap to ground. I think I use 100nF.
 

gazy98

New Member
I made connection with 100nf Cap but it still does not show up in device menager.... can there be a problem with the X2? i dont no much about it .... i just added a 12Mhz because it was written in the Datasheet...

Thanks for the Drawing. It is now exactly like yours connected but still nothing...
 

Visitor

Active Member
Do you have a crystal or an oscillator? Your schematic shows 4 leads, so it looks like an oscillator. I don't think an oscillator needs loading caps, and it does need power and ground connections.
 

Pommie

Well-Known Member
Most Helpful Member
According to the datasheet, V3 needs to be VCC. I trust sparkfun to get things right.

Mike.
Edit, check the schematic on page 5.
Edit2, I assume you're using 3.3V.
 

Visitor

Active Member
...if you are using 3.3v....

This schematic I posted is a proven, well tested design for a 5 volt system. And uses the capacitor to ground as shown in the data sheet. Read the descriptive text.
 

Pommie

Well-Known Member
Most Helpful Member
...if you are using 3.3v....

This schematic I posted is a proven, well tested design for a 5 volt system. And uses the capacitor to ground as shown in the data sheet. Read the descriptive text.
Isn't the STM max voltage 3.6V hence my edit above.

Mike.
 

Visitor

Active Member
The OP's schematic isn't using 3.3v from the CH340 – there's a separate 3.3v linear regulator. I don't know how much current the CH340G can supply.

I left off the V3.3 cap in my first design using the CH340G with a 5v micro, so I recognized the problem immediately.
 

Pommie

Well-Known Member
Most Helpful Member
The OP's schematic isn't using 3.3v from the CH340 – there's a separate 3.3v linear regulator. I don't know how much current the CH340G can supply.

I left off the V3.3 cap in my first design using the CH340G with a 5v micro, so I recognized the problem immediately.
Ahh, hadn't noticed that. I wonder how the STM likes it's pins being driven at 5V?

Mike.
 

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