STM32F405RGT6 custom board connection issue with stm32cubeprogramer and stm32cubeIDE

[rayboum]

Hello everyone.

I have recently made my own STM32 board based on the STM32F405. After soldering all the components and testing all pads and connections, finding them to be wired correctly and checking that the 3.3V is being supplied to all the correct pins, I tried to upload some code but to my shock the STM32F405 isn't establishing a connection via the ST-Link V2 nor the USB cable. After trying multiple fixes, I suspect the issue might be the STM32F405 chip that I got off AliExpress itself. 

So before I took any further steps to replace it, I decided to post my schematics on here for review in case the problem was in my PCB design. If you have any remarks on what might have caused this problem, please share them.

NOTE: The -B label is referring to ground, and P is the VCC.

schematics:

 

 

[TDK]

Schematic looks okay.

Is VCAP around 1.2 V?

Is the chip oriented correctly? Show a picture of the board.

 

[rayboum]

VCAP at 1.2V? Do you mean the voltage across it? If so, I can't check it anymore since I just removed those caps to use them in a PCB that I need urgently done. As for the orientation, it's oriented correctly; I triple-checked. Here is a picture: 

[Chris21]

I suspect Pin 1 is at the lower right corner in this picture, not the lower left like it needs to be.

Which way is the text on the MCU oriented?

 

[rayboum]

Oh no, I clicked on "accepted as solution" instead of "reply." How do I undo this?

The PCB is oriented correctly; the text is just flipped 180 degrees since it's intended to be read from that orientation:

[mƎALLEm]

Look at this post.

[rayboum]

Ok, so from what I understand, this pinout diagram I followed is faulty, as pin 1 (VBAT in the STM32F405 case) is shown at the very top of the row next to the pin 1 indicator and not directly next to it. Is this correct?

 

[Chris21]

If the MCU labeling (text printed on the chip) is not right side up in your photo, pin1 is not at the lower left corner.

[rayboum]

I followed this pinout diagram. Is it wrong?

VBAT is pin 1.

 

[TDK]

> VCAP at 1.2V? Do you mean the voltage across it? If so, I can't check it anymore since I just removed those caps to use them in a PCB that I need urgently done.

Yes.

> As for the orientation, it's oriented correctly; I triple-checked.

How exactly did you check?

The part is oriented wrong, *and* it is now missing VCAP capacitors. Both of these are showstoppers. You will have to fix both of those. It is possible there are other issues. The soldering does not inspire confidence, but the picture is too blurry to spot any particular issues.

[rayboum]

Yeah, the VCAP will have to wait until I buy more since I urgently need them, and I only had those 2. But when they were still on this board (4 hours ago), the problem mentioned was still persisting.

For the orientation, I followed this schematic I found: 

Over here we can see that pin 1 is VBAT:

Following this schematic, pin 1 is directly above the smaller identifier:

According to my PCB layout, pin 1 is to the bottom right of the stm32F405 lable:

And that means it's the bottom left first pin in this picture since it's turned on its right side, and we can see the smaller identifier is under that row of pins, so I think it's oriented correctly unless the first schematic is wrong:

[Chris21]

VBAT is pin 1.  But where is pin 1 on the package?

Read my previous post.

[rayboum]

Yeah, I have read it seems that the pinout diagram i followed was wrong, as pin 1 VBAT is shown to be at the very top of the row that's next to the PIN indicator instead of next to it and i found this other diagram that seems to confirm my suspicions:

-the faulty one I used:

- the one from the Utmel website and the STM32CubeMX interface:

 

[Chris21]

See new post from TDK: https://community.st.com/t5/stm32cubemx-mcus/the-chip-text-orientation-in-stm32cubemx-mx2-does-not-match/td-p/891584

 

[Chris21]

Personally, I don't think that datasheet is very clear.  TN1433 (Reference device marking schematics for STM32 microcontrollers) is better:

Especially as the datasheet also has this:  

which could be misinterpreted.