STM32F103VET6 and CH340G

[gazy98]

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.

 

[Visitor]

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.

 

[Visitor]

Here's the CH340G circuit that works for me. You need the cap from V3 to ground.

 

[gazy98]

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]

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.

 

[gazy98]

i used this one : https://lcsc.com/product-detail/SMD-Crystal-Resonators_Seiko-Epson-Q22FA23V0041800_C91749.html

as i see it is a passive crystal.

 

[Pommie]

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]

...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]

...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]

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]

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.

 

[gclarkii]

Ahh, hadn't noticed that. I wonder how the STM likes it's pins being driven at 5V?

Depends on the pin in question. All most all of a STM32's pins will be 5V tolerant(F0, F1 & F3 at least), except those that are used for analog functions.
In this case, PA9 and PA10 are 5V tolerant, so it won't care if you drive them at 5V...