[RESOLVED] VCP on ST-LINK v3 mini

[Pavel A.]

I cannot get the VCP function of ST-LINK v3 mini working.

Windows sees the com port and can open it

Connected TX output of UART to pin 14 of ST-LINK 3 mini, but nothing is received on the PC side.

Connected some other serial TTL-USB adapter (set to 3.3V), and it works properly.

However, the serial TTL-USB adapter has a ground connection and ST-LINK's VCP has common ground with other functions.

The debugger function works properly.

Is the TX level of VCP 3.3 or 5 V? Does the VCP function work for anyone?

Thanks,

-- pa

[Tesla DeLorean · Accepted solution]

Should be 3.3V

Make sure the RX/TX sense is not reversed. Stick a scope on the pins and send stream of data from PC​

[Paul1]

a) We use the STLINK com port all the time, very convenient with the 14pin MIPI connector.

b) Personally I wouldn't call that VCP as it can be easily confused with STM32 VCP support.

• STLINK provides a USB COM port that can connect to UART pins on the STM32
• STM32 VCP is a method of simulating UART through the STM's USB using only the D+/D- pins, and loading appropriate code in the STM32. We've been using this with USB-C connectors on our boards and it provides a nice robust non-orientation restricting connection which is real nice when the boards are in hard to reach places using easily available cables.

Paul

[Pavel A.]

It was a bad soldering. Some software folks are terrible solders (yes it's me). Thanks.

[Tesla DeLorean]

I'm an electronics guy, but my soldering skills aren't particularly good, but I have technicians with better skills/technique, better eyesight, and better equipment.. and a lot more practice.

Using high power irons (70-80W), with the right bits, right temperature, and right solder do improve the odds significantly.

I also don't like breadboards, and dupont wires, I much prefer wire-wrap and schmartboard jumper wires, type of thing with good metallic bonds, and can survive a trip around a conference table..