STM32 PCB documents/guide

Thread Starter

kalemaxon89

Joined Oct 12, 2022
61
Is there an official ST guide/document explaining how to make the PCB when using an stm?
For example I found these documents (which I attach).
Do they suit me? Is there any other interesting document I missed?

There are thousands of very interesting tutorials on the internet (like Phil's Lab), but I was looking for something official from ST.

Another question, is there much distinction between the 'rules' to be followed when making a pcb using a board (like stm32f407) vs. using MCU/MPU (like stm32f103ct6)?

If however you know of any very useful and well done documents/tutorials/videos that are not from ST .. attach them to me anyway. I currently have to make a pcb using the stm32f103ct6 and have never done it.

Thanks to everyone!
 

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MrChips

Joined Oct 2, 2009
27,686
There are no rules or guidelines to laying out a PCB that are specific to STM32 MCUs.
The same rules and guidelines apply to almost any MCU.

Generally, you need to consider whether you need to lay out a single sided, double sided, or multilayer board.
Since most components today use SMD parts, it is possible to create just a single sided PCB. However, there are many advantages to going to double sided PCB. It is difficult to DIY a fine line PCB and you are more likely to use a PCB shop to manufacture the board. Unless it is a very complex layout most circuits can be laid out on a double sided PCB.

The important rules to follow would be to pay attention to power rails, supply and ground, and make provision for 100nF ceramic chip capacitors. Do not omit any power and ground pins. Make sure that they are all connected to low impedance paths. You will benefit by using floods and ground planes. Put a power or ground flood plane underneath the MCU chip.

STM32 MCUs have specific requirements on power supply decoupling capacitors. Read the datasheets for both STM32F1xx and STm32F4xx for PCB compatibility issues. Moreover, there are two VCAP pins that must be used as per datasheets. If these are not done correctly the MCU will not run.

If this is a mixed signal application, i.e., analog signals are involved, definitely use separate ground planes, one for analog and one for digital. Connect the two at one junction at the power supply entry point in order to prevent ground loops. Again, ground planes are very helpful. It is more convenient to place the ground plane on the bottom side of the board.

The usual PCB rules apply. Keep traces short and wide enough of the current required. Keep 100nF power supply decoupling capacitors close to supply pins. Connect the ground side to the ground plane. Have at least one 10-100μF power filter electrolytic capacitor on the board at the power supply entry point.

If you have unused pins on the MCU, it would be useful to bring them out to a SMD pad if space allows. You never know when you have to add some other feature to the board. Have at least one GPIO pin connected to a test header pin for debugging purposes. Also provide a solid connection to the ground plane that can accommodate a wire loop for attaching the ground clip of your oscilloscope. If you need to make current and power consumption measurements, add a 2-pin header in series with the input supply rail. If you are still at the debugging stage, having a RESET button could come in handy but not essential.

Hope this is helpful.
 
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