Which pins are usable on the F429 Discovery (DISC1) board?

[Lars Beiderbecke]

Posted on December 31, 2017 at 10:32

I'm using the STM32F429 Discovery Board. Comparing to the Nucleos, most pins seem to be used by peripherals.

I disabled those peripherals I don't need (e.g., LCD, USART, ...) to free some pins, but I found some pins (e.g., PB13) are still used by some peripheral (i.e., they interfere with my logic), although they show as free in CubeMX.

Is there a list of pins that are reserved for the board itself even when all peripherals are disabled?  I know about LEDs and button, but what about ST Link and others?

There is some official diagram of both pin headers which categorizes all pins into 'without conflict' and 'connected to other components' (

https://os.mbed.com/platforms/ST-Discovery-F429ZI/

 ). I don't understand this list. Is this the answer to my question, or are they talking about conflicts between two or more peripherals (of which some are not shown in the diagram)?#pins

[Tesla DeLorean]

Posted on December 31, 2017 at 13:59

Relatively few, there is a table in the User Manual list pins including Free ones.

[Lars Beiderbecke]

Posted on December 31, 2017 at 14:09

No, I mean if you disable all peripherals, which ones are still not usable?

If you create a new project in CubeMX, the program will show some pins in green, not orange. I assume that the green pins are the ones that are used permanently, even if they belong to disabled peripherals?

[Bogdan Golab]

Posted on December 31, 2017 at 14:45

Yes, if it comes to this board SDRAM and LCD consume huge number of pins. CubeMX marks these pins for the particular purpose so let's talk about the particular issue Lars is facing. So, what kind of functionality / pins is needed? The electrical issues require the ability to read the schematic...I prefer this way when going to assess if something conflicts with my stuff.

[Bogdan Golab]

Posted on December 31, 2017 at 14:31

Look into the schematic to understand what is going on at the circuit level - 'pin connected to other component' may conflict with your hardware (also connected to the same pin)

[Tesla DeLorean]

Posted on December 31, 2017 at 14:32

Not sure how CubeMX manages things at a board level. A significant number of pins on the STM32F429I-DISCx boards are attached to external components (SDRAM, LCD, etc) which are going to physically interfere with other use cases.

Start as if you were just using the STM32F429ZIT6 part, it should provide ungated access.

[Tesla DeLorean]

Posted on December 31, 2017 at 14:54

As I've observed over many years the STM32F429I-DISCO has very limited expansion/experimentation options. The current pin usage makes ETHERNET or SDIO attachment impractical.

The NUCLEO-F429ZI would make for a much better breakout board, it has ETHERNET but lacks LCD/SDRAM

[Lars Beiderbecke]

Posted on December 31, 2017 at 15:03

I've looked at the schematics, but it didn't help me. Yes, things are connected to things, but this I can see in CubeMX as well. What I don't know is if some of these pins are connected to some active components that cannot be deactivated at all, or to some components that interfere with the signal even when the peripheral is not in use.

So, can I use all of the LCD pins for other purposes if I'm not using the LCD at all? Can I use the USB_OTG_HS pins if I'm not using USB at all?

[Lars Beiderbecke]

Posted on December 31, 2017 at 15:04

Clive, I've come specifically for the SDRAM.  

[Bogdan Golab]

Posted on December 31, 2017 at 15:21

The ILI9341 is connected to the LTDC:

https://cdn-shop.adafruit.com/datasheets/ILI9341.pdf