[Solved] USB device not enumerated

[tpphysik]

Posted on August 01, 2014 at 15:14

Hello,

I'm trying to get the USB Virtual COM port loopback example project work on STM32F102.

When the USB is connected, the PC says ''Unkown device connected'' with VID 0 PID 0 so obviously it's not enumerated.

On the MCU side, it detects that the USB was attached, but goes to suspend state after 2 seconds or so. The device state is ''ATTACHED'', doesn't ever get to CONFIGURED.

It should be software problem because the hardware looks ok. I have 33 ohm series resistors on DP and DM lines, 1,5k pullup on DP, and VBUS wired to PortA 9 through a 10k resistor.

The system and usb clock setup also look good.

What could cause the device not enumerate and the device entering suspend mode when connected (no communication)?

[tpphysik]

Posted on August 05, 2014 at 19:38

Anybody? I can elaborate if you ask.

And what voltage should I measure on DP and DM lines when the usb cable is connected?

[Tesla DeLorean]

Posted on August 05, 2014 at 21:20

Hard to say, what compiler/tool-chain are you using? GNU-GCC?

Are you absolutely sure the clocks and PLLs are set up correctly, and you have a 48 MHz clock internally. Check internal clocks with MCO pin (PA8)

Review schematic/electrical levels for assorted STM32-DISCO boards using an F103 part.

[schauer]

Posted on August 06, 2014 at 10:34

Vaclav,

are you absolutely sure, that the D+ and D- lanes are connected correctly (1:1)?

[tpphysik]

Posted on August 06, 2014 at 16:56

Thank you, the problem was really with the clock setup. The example codes and the SetSysClock functions expect an 8 MHz crystal but on my board it's 4 MHz.

Now it's working.