stm32f411 PCB fail?

[RafaelJureg]

I made a stm32f411 simple test board and I am failing to do some things with it, now I am trying to send a string using the usb cdc, the code is uploaded but the device is not shown in usb list, I have a stm32f411 blackpill with 25mhz crystal hse(in my custom pcb the crystal is PTH instead of SMD) and the code works as expected, what i be doing wrong? here is the schematic please remember it's my first time making a custom board and I was aiming a very simple design:schematic

[AScha.3 · Accepted solution]

Wrong : no cap on VCAP pin. This is the core voltage....so it will not run correct.

See rm or circuit of a nucleo, what to have there.

on black pill:

[RafaelJureg]

***, is this really mandatory? what other tips would you give me to avoid making other mistakes?

[TDK]

Yes, VCAP is mandatory.

I'm guessing pin 2 of U2 should be the +3.3 V net. It's not marked on the schematic.

Those appear to be the only mistakes.

Consider reviewing the hardware design guide:

Getting started with STM32F4xxxx MCU hardware development - Application note

[Tesla DeLorean]

Yes, it's the bulk capacitance for the 1.25V internal LDO regulator.

Without the board will be very unstable beyond HSI frequency, likely to Hard Fault, and FLASH fail to program.

Single pin VCAP should be 4.7uF  (for two pins, 2.2uF each), please check data sheet