Software SPI

[Nico3]

Hello friends, 

I need to connect thirdparty accelerometer SENSOR to STM32F4 series MCU via SPI. 

The Sensor Data sheet says:

1) Designed to support any MCU  that used software implemented SPI. It is not designed to support any particular hardware implemented SPI.

2) MISO: data bits are shifted out on falling edge of SCK

3) MOSI: each bit is sampled on the rising edge of SCK. 

4) Sensor supports full duplex communication

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Please suggest how to implement. Can I use SPI peripheral of MCU? If yes, I am not sure about what should be CPHA for CPOL = 0. 

I need full duplex communication.

[######]

Hello,

What is the part number / datasheet link for the sensor?

Thanks

[Andrew Neil]

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@Nico3 wrote:

thirdparty accelerometer 

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Why so secretive? Tell us the manufacturer and part number!

How to write your question to maximize your chances to find a solution

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@Nico3 wrote:

The Sensor Data sheet says:

1) Designed to support any MCU  that used software implemented SPI..

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That's an odd thing to say!

Please post a link to the datasheet - so that we can see exactly what they said, in context.

Have you tried an internet search for "STM32 + <sensor part number>" ?

[Nico3]

Murata is mfg. Please find the detailed data sheet attached. On page 20, it mentions about SPI.   I planned to use P/N SCA3100-D04.  

[Nico3]

STM32+ SCA3100-D04 internet search already tried. Couldn't find anything. All information about sensor posted in below post.

thanks

[Andrew Neil]

Thanks.

Indeed, there it is:

You'll have to contact Murata to ask them what they actually mean by that.

But the Murata SPI frame is shown here:

And the STM32's is here:

https://www.st.com/resource/en/reference_manual/rm0368-stm32f401xbc-and-stm32f401xde-advanced-armbased-32bit-mcus-stmicroelectronics.pdf#page=565

via: https://www.st.com/en/microcontrollers-microprocessors/stm32f401rd.html#documentation

So see which one matches.

There's only 4 modes to choose from ...

https://en.wikipedia.org/wiki/Serial_Peripheral_Interface#Mode_numbers

[Andrew Neil]

Note that the "automatic" NSS operation in the STM32F4 is probably not what you expect - or want:

So you'll probably want to do it "manually" in your software.

[Nico3]

I think this is what they meant when they are saying Hardware and software. i have to use CS pin manually.    Other than this,   I am yet  to find out CHPA polarity.

I think the lanugage written in manual is confusing ..looks like auto converted from Chinese/Japanese to English...

[Andrew Neil]

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@Nico3 wrote:

I think this is what they meant when they are saying Hardware and software. i have to use CS pin manually

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I very much doubt it - that's a specific STM32 gotcha!

Yes, it does look like something got lost in translation.

Please feed back to Murata!

[TDK · Accepted solution]

CPOL = 0 and CPHA = 0 clearly from the SPI diagram.

The chip doesn't know if you're using software or hardware SPI. It'll work fine with hardware SPI.