SPI discussion - anybody?

Since I got "why would you wanna do that " cold shoulder response to my original post I am reposting it here.
I would like to discuss these issues with somebody who is interested in solution. On forum or PM.

I need to implement SPI and currently have no physical access to Due SPI header pins.

So I am looking for alternative hardware connections.

It looks as SPI0 has some hardware access using general I/O pins, but I do not see MOSI for that.
Also SAM3x8E doc goes into "A and B " multiplexing which may also be a applicable.

Anyway, anybody REALLY interested to discuss SPI, not my projects?


Why you have "no physical access to Due SPI header pins" ?

I see nothing in the datasheet that suggests there are ANY options for changing the pins used for either SPI interface - they are hard-wired. If you don't have access to the SPI header, then your only option is using regular I/Os for a bit-banged software SPI interface.

Ray L.

Why you have "no physical access to Due SPI header pins" ?

good question -- just in case the answer is "some shield hides SPI pins" I posted a solution I did like but many others did not :wink:


Remove the header and re-install from the other side of the PCB… Or, solder wires to the header, to create an “SPI pig-tail”.

Ray L.

I use something like this


can't you make a small header so to use a flat ribbon cable

32.6.1 I/O Lines
The pins used for interfacing the compliant external dev
ices may be multiplexed with
PIO lines. The programmer
must first program the PIO controllers to assign
the SPI pins to their peripheral functions

Could this be what I am looking for?
Or is it still hardware multiplexing?
That is no clear.

I got rid of the proto shield, so I have standard access to SPI header.
Still like to see software solution.