NUCLEO-F756ZG SPI1 issue

[AHape.1]

Dear ST,

I try to use SPI1 in full-duplex slave mode with hardware NSS and interrupts.

Interrupts work fine, the only problem is that data is all 0

After connecting the logic analyzer I noticed that the CS and SCK signals are ok but the MOSI and MISO are low.

I generate the SPI data using MCP2210 breakout board, it works fine if I connect only the logic analyzer to the MCP2210 all signals are fine. when adding the nucleo in the circuit MISO and MOSI are pulled low!!! 

I use CubeMX for configuration

pins are:

PA5 - SPI1_SCK

PA6 - SPI1_MISO

PA7 - SPI1_MOSI

PA4 - SPI1_NSS

Has anyone ever seen anything similar.. where to look for the issue ?

Thank you

[TDK · Accepted solution]

PA7 is used by the ethernet. If you want to use it as SPI, you'll need to remove JP6.

Use the schematic to determine what pins are actually available. Consider defining them as GPIO output and toggling and monitoring with a logic analyzer or multimeter to ensure the pin is making it to the header you're connected to.

https://www.st.com/en/evaluation-tools/nucleo-f756zg.html#cad-resources

[AHape.1]

Thank you TDK,

In the link you send me, in the MB1137 PDF - "nucleo-144 for everything" the text on the schematic around the arduino connector is misleading x(

I changed the pins allocations and now it works fine!

where do I find the schematic for nucleo-f756ZG ???

[TDK]

> In the link you send me, in the MB1137 PDF - "nucleo-144 for everything" the text on the schematic around the arduino connector is misleading x(

What is misleading about it? I see you have posted a screenshot with a red rectangle, but I see no issue with what's in the rectangle.

> where do I find the schematic for nucleo-f756ZG ???

I posted the link in my last response.

[Tesla DeLorean]

>>where do I find the schematic for nucleo-f756ZG ???

I don't think there is one specifically, the MB1137 is the primary reference, the BoM for the F756ZG specifically might call out fitted/not-fitted component and jumper level differences.

ST has fairly consistent pin usage across the 144-pin models

[AHape.1]

Hi All,

First,  thank you for all the help.

I try to get used to ST tools... It will take me a while to get used to them.

Another small question: where do i find a document that contains a table of all alternative functions for the pins , for f756 ??

I had to go pin by pin with the mouse in cubeMX ... it wasn't fun

Thank you very much

Andy

[TDK]

The datasheet lists all pins and their AFs. Google "stm32f756 datasheet" to find it easily.

You can also enable the peripheral and it will find an appropriate pin for it, which you can find alternatives for with ctrl+click/hold.

[AHape.1]

Bless you TDK,

I completely forgot that ST has separe Datasheet from Reference Manual