USB issue with STM32F411

[marcmign]

This has nothing to do with EEPROM devices, but that was the only "labeI" that would work. I built a custom board using an STM32F411RET6. It has a 12MHz external clock. I'm trying to use a VCP USB interface. The USB code enumerates fine on a 'F407 DISCO board (STM3240G-EVAL), of course with the 25MHz crystal instead of my 12MHz oscillator. But I get the attached USB connection error with my custom board. This interface won't allow me to attach a .zip of my code, and only 3 attachments are allowed, but I can send the CubeMX file I am using, and the actual code.

[TDK]

Your clock setup and schematic look fine. I would expect it to be a code issue.

Debug your code, ensure all the USB functions are passing correctly.

[marcmign · Accepted solution]

It turned out that the LDO I was using to generate 3.3V from the USB VBUS was only outputing 2V. I changed the feedback resistors on the LDO to give 3.3V, and it started working.