Using a stand-alone STM32

[Lars Beiderbecke]

Posted on February 05, 2018 at 21:46

I want to move from a Nucleo board to a PCB with a 'stand-alone' STM32F7.

The STM32 Hardware Development Guide had great information, but I'm still a bit unclear about some issues:

1. The guide emphasizes that the voltage of  VDD_USB and others must stay below VDD during startup. Is there something I have to do, or is this already handled internally?

2. When I attach a backup battery, can I just keep it connected even when running with VDD? The Guide suggests no, but a ST presentations says yes.

3. Is there a reason for disabling the voltage regulator with PDR_ON, or can I just connect it to VDD?

4. For the SDMMC, it is advised to 'reference the plane using GND or PWR' - come again?

[T J]

Posted on February 05, 2018 at 22:06

Hi,

I would strongly recommend that you use Kicad.

I have a F767Zi on a board.

I found a reset chip works 100% of the time.

[Lars Beiderbecke]

Posted on February 06, 2018 at 17:27

While I do use Kicad, this doesn't answer any of my questions.

[Vasile Guta_Ciucur]

Posted on February 06, 2018 at 18:13

TJ, that is the minimum required to have a functional board? What if I need USB connectivity?

[T J]

Posted on February 06, 2018 at 21:55

The reference plane mentioned above is talking about 4/6 layer boards with large power planes.

These are used for current density and heat removal.

in your case with almost no power consumption, you would probably be able to make a 2 layer board.

the SDMMC however will require extra bypass caps if you use a 2 layer board.

VddUSB not sure,mine is attached to 3V3. Check the STLink programmer board, Check the Disco eval boards.

When you ask about battery backup, are you talking about the RAM inside the processor ? or the whole board ?

My F767 board is 2 layer.

Guta_Ciucur.Vasile

the minimal functionality USB solution is exactly the same circuit as the F103 STlink programmer.

[T J]

Posted on February 06, 2018 at 22:08

Which processor are you looking at ?

do you have Kicad ?

generally you don't need any crystals, so there is not much on the board...

[Lars Beiderbecke]

Posted on February 06, 2018 at 22:10

Thank you for your answers, this is helpful. I also plan to use a 2-layer board.

The question about VDDUSB was about the requirement that VDDUSB must not exceed VDD during power-on (according to the Hardware Guide). I assume this is enforced internally by the voltage regulator, but I wasn't sure.

BTW, if I'm not using USB at all, do I still need to supply VDDUSB, and, more importantly, the capacitors for VDDUSB?

The battery backup is for the backup RAM, i.e., attached to VBAT. The ST Reference Design shows a switch there, but I'm not sure if it is actually required.

[T J]

Posted on February 06, 2018 at 22:16

[Vasile Guta_Ciucur]

Posted on February 07, 2018 at 05:09

Actually, I tried to break the ice... right now, the Nucleo I have is enough but good to know, thank you! Yes, I have KiCAD,

[Joerg Wagner]

Posted on May 01, 2018 at 22:41

Which part number of MIC803 exactly concerning nominal Vth and tRESET?