Hello guys,
I'm very new to STM32s so please bear with me. Any help would be greatly appreciated. I am currently making a scratch-built STM32 board. I soldered on an STM32F407VET6 onto a QFP100 breakout board and I'm wiring together a minimal system on a through-hole protoboard. I used this schematic of a cheap STM32 board I bought as a reference design and also constantly referred to ST's official design guidelines. I believe I made a proper "minimal setup" required for my STM32 to run properly. However, when I plug it into my computer, nothing is detected. I know I have the proper USB drivers installed because my STM32 discovery board works fine. Here is what I've done so far:
- check my STM32 soldering job for any shorts. I don't see any.
- I took a multimeter and probed through my circuit, checking all signal lines such as USB, the 8MHz and 32KHz crystals, power supply, etc.
- I added 2.2uf caps to each of the two VCAP pins, connecting the other legs to ground. Also added 22Ohm resistors to the USB signals. 22pf caps to the 8MHz crystal, 12pf caps for the 32KHz crystal.
- added switches for BOOT0, BOOT1 and a reset button, and they all work as they should according to my multimeter. I also checked multiple times to make sure the boot config jumpers were in the right position.
- checked if all my resistors have the proper values. They do.
Here's what I didn't do so far:
- I don't have an oscilloscope or signal probe, so I can't actually check for a pulse of any kind. The only visual feedback I get is the LED from my power supply, which works fine.
- I didn't add a JTAG/SWD header. I figured I wouldn't need it since for now, I just want to see if my laptop detects the STM32's USB DFU mode when it's plugged in.
- I didn't add all the decoupling caps to each of the VDD/VSS pins on my chip. I figured it's not absolutely necessary for function, since I've gone without them in AVR chips many times without issues.
After many hours of head-scratching and frustration, I'm gassed out. I can't possibly think of anything else I might've missed. Maybe my chip is defective/fried, but I didn't do anything to it that could've fried it. So please, help a brother out! Again, I am pretty new to STM32s, so thank you for staying with me and any help is welcome!
Thanks!
P.S. I figured photos wouldn't be much help at all since my wiring job is absolutely atrocious and it wouldn't give any useful info. But if y'all want it, I can certainly post it here. Oh also, in case you're curious, I'm making this custom board to prototype my design for a custom PCB using the same chip.
