STM32F405RGT6 custom board not working

[frotaitalos]

Hi guys, this is my first post here on the forum. I'm starting my learning in STM and I created a custom board with a STM32F405RGT6, I followed a basic MCU operation schematic that I found in a video on Youtube, but the MCU is not starting. I did several tests to check if the USB connection was correct, if the voltages also worked well and everything is ok. However, I saw that I really don't get a clock from the crystal, the crystal I'm using is already known to me from other projects. So I'm leaving here a print of the connection schematic and if anyone can give me some light on where to look for the problem that causes the MCU to not start, I would be very grateful.:grinning_face:

 

[liaifat85]

I think it's wise to check your PCB and troubleshoot if needed. 

[frotaitalos]

Hi guy, thanks for your reply. I have already done all the checking on my PCB and the schematic is being fully respected, I am a guitar pedal manufacturer and have a lot of experience with custom boards from other MCUs (Atmel and ESP). Can you see a connection error or a pin that should have a connection and is floating in the image I attached?

[TDK]

Did you fix the VCAP errors? Going to be hard if you didn't put any traces/pads on those pins. Is the voltage on VCAP ~1.2V?

 

Once it's set up right, you should be able to open STM32CubeProgrammer and hit connect to connect to the device.

[mƎALLEm]

Hello,

You need to refer to the STM32F4 hardware getting started AN4488 and refer to the schematics.

From your schematics at least VCAPx capacitors are missing:

 

[TDK]

Can STM32CubeProgrammer connect to it? Looks like VCAP is the only issue, but it wouldn't respond at all if that were the case. The crystal won't put out a signal until you run a program that activates it.

 

Design guide:

https://www.st.com/resource/en/application_note/an4488-getting-started-with-stm32f4xxxx-mcu-hardware-development-stmicroelectronics.pdf

 

[mƎALLEm]

Forget about the crystal for now and try to run with HSI as clock source for system clock:

Do you face the same issue?

[frotaitalos]

My attitude must be very noob, but I was just hoping to connect the MCU via USB and some device would appear on the computer, apparently this isn't the initial step, right?

Is the connection header I created (J1) or is there a pin missing from it? I have a ST LINK-V3 MINI DEBUGGER, should I use it to do this initial MCU configuration?

I really apologize for questions that should be very simple for those who are already used to MTS, but my knowledge of these devices is really minimal.

[frotaitalos]

Does the St-link V2 Mini also serve to communicate with the STM32F405RGT6?

[mƎALLEm]

"Does the St-link V2 Mini also serve to communicate with the STM32F405RGT6?"

--> Yes

[frotaitalos]

Excellent, I haven't found the ST V3 in my laboratory, so I'm going to buy this V2.

[mƎALLEm]

Also, I didn't notice this at first glance:

You're connecting OSC_IN and OSC_OUT to PC4 and PC5 while it should be connected to PH0 and PH1 like provided in the datasheet:

I'm wondering what kind of Youtube link you're referring to!

 

[frotaitalos]

Hi Guys, I managed to communicate with the STM via USB and record a hello word on it.

I didn't have access to st link v2 and v3. However, I managed to correct the layout errors on my custom PCB. The crystal oscillator was actually on the wrong pins and the lack of VCAPs prevented the STM from starting. I managed to solder these components to the STM pins and everything worked.

Thank you for your support, I will be more attentive when following youtubers schematic :grinning_face_with_sweat: