Spi between Due and Uno

Projects Networking, Protocols, and Devices
1

Hy Guys,

I'm trying to execute a rutine to send a led state from Due to Uno and refresh it.

Here is a photo of the story:
https://scontent-b-mad.xx.fbcdn.net/hphotos-prn2/t1.0-9/10403583_10152475983838112_6757633011822563129_n.jpg

Here is the code for Due and Uno. It works great for first step, but no refresh is do it...

And the video:

So, my doubt is: The SS pin from Due is in 3.3v, but in Uno is i/o pin in 5v. So maybe It has problems to detect the high and low level from Uno?

So... help?

2

The SS pin from Due is in 3.3v, but in Uno is i/o pin in 5v. So maybe It has problems

Want to kill the Due?
That is a good way of doing it.
How is it wired? Schematic?

3

Hy Grumpy_Mike,

Yes it seems its a good way to kill Due :P,

But the SS pin is defined in Due like an out, and in Uno is defined like an in. If Due is Master and Uno is a Slave, the comunication is only in one way (from Due to Uno)

So I think maybe the problem is that the Uno can't recognices the "high" logic level because works in 5v.

And here is the point, Maybe if I use a mosfet to open a 5v circuit for Uno. Could be a way to work. Or maybe if I can define an analogical input to define what is "high" and "low" state...

For the wires conection:

digital in pin 9 with a push button in Due
digital out pin 8 with led in both Arduinos
Spi conextion between like in the photo.

Any idea?

4

Spi conextion between like in the photo.

In the photo I cannot see a SS connection but you have connected all the other ICSP pins as it looks like. That's a rather bad idea because at least on the UNO side the RESET and the Vcc line are at 5V. The reset line goes directly to he Due's reset input which may kill it while the connected 5V may produce power supply loops with also bad effects. The MISO pin is an output on the UNO (in your configuration) so there 5V kill the corresponding pin on the Due too.

You should invest into a bidirectional level converter: p.e. https://www.sparkfun.com/products/12009