Enumeration of virtual com port fails

christoph239955_stm1 · ‎2009-07-08

Posted on July 08, 2009 at 16:27

christoph239955_stm1 · ‎2011-05-17

Posted on May 17, 2011 at 13:16

I'm working with Codesourcery Lite and an Olimex board for the STM32F103RBT6 (article STM32-P103). The standard library works fine but I've got some trouble with the USB firmware library. Compiling the USB library and the virtual com port example works fine, but after flashing the chip, the enumeration of the USB device fails.

I used the original code from the latest version of the library, and added just a blinking led, changed the pin for controlling the 1K5 pull up resistor on the D+ line and switched the usart to USART2.

After the usb initialization, the led is blinking, and I can transmit data via the usart. But Windows shows just a message, that an unknown device was found. A trace of the USB port (attachement!) proofs that there is no response from the STM32.

I've no JTAG, but with the led, I can proof that the usb interrupt service routine is never called and the controller runs through the USB init routines.

Has anyone an idea, what is wrong? Or just any hints what I can do to find the bug?

christoph239955_stm1 · ‎2011-05-17

Posted on May 17, 2011 at 13:16

Sorry, I've attached the wrong trace (of the USB hub)...

As you can regarding the new trace, the response from the STM32F103 is always 0x0000. It seems as if the interrupt service routine is never executed - but why? Is there anything special about this routine? My other interrupts (USART, ADC, etc.) are executed...

christoph239955_stm1 · ‎2011-05-17

Posted on May 17, 2011 at 13:16

I got it, I used the wrong start up code, from version 1 of the STM32 standard library. It works fine now.