Need help with determining pinout of STMod+ ext. board on STM32H750B-DK board

[bully]

Hello,

I'd kindly ask for some help on determining exactly which MCU pin is connected to STMod+ extension board.

Which pins exactly are connected to STMod+ pins 2 and 3 ?

It seems like two choices for both pins, but I'm not sure how to check/modify which comes to STMod+ connector?

I guess from schematic that PI2 amd PB15 are connected to pins 2 NS 3, but that would mean that I don't have 

USART device on STMod+ connector ?

Thanks in advance,

regards.

[SofLit]

Hello,

 

->By default: SB is soldered

-> By default: SB not soldered

So here you can deduct which pin is connected and which is not. 

By default: PB15 is connected to P1/2 and PI2 is connected to P1/3

[bully]

Hello,

thanks for response... But that means that no U(S)ART interface is present on STMod+ by default

and we have to change with soldering of  SBs ?

Is there any special reason that PI2 and PB15 are present by defaiult instead of USART2 pins ?

Thanks.

[SofLit · Accepted solution]

Hello,

According to the STM32H750 datasheet:

USART1_RX is available on PB15 (by default).

On PI2 there is no UART/USART available.

Alternative by using USART2 on the following GPIOs:

PD5: USART2_TX 

PD6: USART2_RX

Achieved by removing SB13 (PB15) and soldering SB16 (PD5) and by removing SB11 (PI2) and soldering SB12 (PD6).

Hope it does answer your question.

[bully]

Hi, thanks for response...

I see now, it's a pity, that UART is not present by default.

That also means that ESP (CN4) and Groove-NFC interfaces are not functional,

since they base on UART device. 

It would be more usable, at least for our students...

We have few hundreds of these boards and it's not convenient to solder all of them..

Thanks, regards.

[bully]

Hello,

maybe I'm wrong, but it seems that we can get USART1 TX and RX instead of SPI2 interface.

I'm attaching my sketches.

Regards.

[SofLit]

Hello,

According to the connector sketch you shared only USART1_RX is available on PB15. USART1_Tx is not available.

You need toc check the avalable alternate fuction in the datasheet: Table 7. STM32H750xB pin/ball definition

So you need to modify the board as I described above to use USART2

[Tesla DeLorean]

These boards tend to be the result of lots of compromises and kitchen-sinking, where a lot of peripherals fight for escape and usage.

LCD + SDRAM tend to eat a lot of pins.

You might have more joy getting interfaces out the Arduino shield connection, perhaps making a simple interface shield for Grove I2C or UART.  

Not saying this is wired helpfully, but one could JLCPCB or OSHPARK something

https://www.mikroe.com/arduino-uno-click-shield

>>.. it's not convenient to solder all of them..

Or an opportunity to teach SMT soldering skills?

[bully]

Hello,

I meant PB14...So if you don't need SPI2 MISO, then you get USART rx, tx interface... But I guess clickboards with UART will have uart pins on RX,TX... So partial solution, but it is...

Regards.

[SofLit]

Yes but does it fit with the module connections (already hardwired to CN10/2&3)? That's the question.. unless you will introduce a modification on the module which you avoid to do it (as you said before). 

Unless I'm missing something...