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Topic: Maximum Pin Usage on Due (any duplicate/dedicated pins?) (Read 1 time) previous topic - next topic

poodull

I would like to use the most pins possible on my Due.  I have read in a few places that some pins are duplicates?

I cannot read a pin schematic and make heads or tales of it.  It says that D10 = D77 and D4 = D87... are those duplicates in the CODE, or on the physical board?

anyway, I'm using Serial over USB.  

My question in the most clear way I can put it:
Looking at the board, which physical pins can I use as Digital IO and which ones are duplicates or unavailable because of Serial.  I think 0 and 1 are used for serial?

Followup:  What about if I (additionally) use the dedicated SPI pins in the middle (for SPI)?  What pins are those duplicates of?

Thanks and sorry if this is obvious to some of you.  I honestly can't read that schematic and I've been looking at it since November, way before I got the Due.

bobcousins


I would like to use the most pins possible on my Due.  I have read in a few places that some pins are duplicates?

I cannot read a pin schematic and make heads or tales of it.  It says that D10 = D77 and D4 = D87... are those duplicates in the CODE, or on the physical board?


They are physically shared signals on the board. I think they are the only two lines shared in this way. All the other lines are mapped 1:1 with pins on the the SAM3X.

Quote
Followup:  What about if I (additionally) use the dedicated SPI pins in the middle (for SPI)?  What pins are those duplicates of?


You can use MISO, MOSI and SCLK on that connector, and they are not physically shared with other pins.

That is how I read the schematic, I am sure if I am wrong someone will correct me :)
Please don't PM me asking for help. Ask questions in the forum.

poodull

Awesome, thanks for the reply.  I hope you're right.

About the dedicated SPI pins... is that SPI0, SPI1?  All of the example code uses the typical SPI static class and refers to 13 and 11 as MOSI and SCLK.

If I use the middle MOSI and SCLK (all I need for my w2801s), can I use 13 and 11 (or 9 and 50 for that matter) for DIO?

Thanks again for trying to help.

bobcousins

The dedicated SPI is just SPI, I think, there is only one SPI supported by the Due SPI library. The Due pins are numbered D74,D75 and D76 and these are the pins used by SPI lib.

I'm not sure about the SPI-CSx pins, are they used in Master or Slave mode? SPI-CS3 is not mapped anywhere (unconnected on SAM3X), so if you don't want SS/CS then specifying BOARD_SPI_SS3 will ensure the SPI does not interfere with other pins.
Please don't PM me asking for help. Ask questions in the forum.

poodull

BOARD_SPI_SS3 ?

That's interesting.  Do you have any sample code or documentation for that?  Google comes up blank.  Again, sorry if that's obvious but I can't find anything on it.

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