Quick question for DE0-Nano owners

jac_goudsmit

I'm working on designing a PCB that can be plugged into the DE0-Nano, DE2-115, BeMicroCV and BeMicroCV-A9. I only own the BeMicro's so I want to confirm: is the distance (center-to-center) between the two extension headers on the DE0-Nano equal to 1.6 inches (just like on the BeMicro's)?

Thanks!

===Jac

ozpropdev

Jac
Sadly the spacing is not the same.
IIRC the difference is 0.1 inch.
Tubular had a post/thread on this forum about this very subject with pictures too.
Can't seem to find it though.
My nano is buried in some other hardware at the moment so I can't check it against the Bemicro boards.

Ariba

No it's 1.7 inches on the Nano.
Is the pinout compatible at all, mainly the power pin locations?

Andy

Tubular

Yeah, different spacing by 0.1".

One of the bemicro headers is de0-nano compatible. The other one (that has sparse lvds) is really not.

With care its possible to have a 3 row header that can be attached to either DE0 or BeMicro, with some GPIO pins of the 3rd row attached to pins in the 1st row (the 2nd row always connects regardless). Hope that makes sense

jac_goudsmit

I took some measurements from a high-resolution picture and it looks like you guys are right: 1.7 inch. I also had to do a double-take to notice that J2 on the DE-0 is mounted ANTI-parallel to J1: pin 1 is on left on one header, on the right of the other header.

As for compatibility between headers: I gave up on that pretty much right away. Too many incompatibilities, especially if you take the secondary headers into account. The BeMicroCV-A9 has barely enough functional pins on the first header to implement all 32 pins of the standard Propeller, plus the reset line. Somewhat ironically, the DE0-Nano has the most usable pins on the header (enough for 32 pins port A, 32 pins port B and an additional 7 pins -- I say ironic because it's the only hardware that doesn't fit the entire Propeller - you have to disable the font ROM). The BeMicro is somewhere in between.

So the board has 6 headers for now, on the bottom side, which can be aligned in 3 ways. Headers 1 and 4 are for the DE0-Nano, headers 2 and 5 are for the BeMicroCV-A9 and headers 3 and 6 are for the BeMicro and DE2-115. The DE2-115 only has one header but it's laid out the same way as J1 of the BeMicroCV, and it looks like it will be possible to just put my board on the DE2-115 (if the acrylic cover is removed) leaving the other connector disconnected.

The following screenshot shows what I mean:


The picture shows two EEPROMS in between the headers but there might not be enough space for all the traces if I do that. It looks like I already have to use a 4 layer board to get all the traces on there.

Outside the picture, there's a QuickStart header, a header that has the same pinout as the DIP40 propeller (for in-circuit debugging) and a Prop plug header (I'm considering adding an FTDI chip straight onto the board but this is not likely to happen). There are also three patch headers that make it possible to connect the bottom side headers to the top side headers in pretty much any way conceivable. But because I have those patch headers anyway, I may just decide to do away with most of the bottom side headers. This is all up in the air at this time.

As soon as I finish the layout, this will be added to my Github repo.

Thanks for your help, guys!

===Jac

Tubular

The other thing to throw out there, is that the headers on the 1-2-3 boards match the exact spacing (but not exact pinout) of the DE0-nano.

On the 1-2-3's there's a block of 4 power pins at each end of each 40 pin header, all the pins in between are gpio. So, there's plenty of gpio overlap

jac_goudsmit

Tubular wrote: »

The other thing to throw out there, is that the headers on the 1-2-3 boards match the exact spacing (but not exact pinout) of the DE0-nano.

I forgot the 1-2-3 had two double headers too! I'll try and work those into the design. I might even make the top side identical to the 1-2-3 layout (with two headers and space for a breadboard in the middle) so it will be possible to use future plugin boards for the 1-2-3 with my board too.

I got some really good ideas floating around in my head now. I'll probably abandon the idea of using the six headers on the bottom side and I'll extend the idea of the patch headers. This will leave more space to do things and will allow me to do a 2 layer board. I think I'll turn the "bed of nails" idea that I had before for the patch headers, into a "pincushion" idea: the headers will be female so you can plug wires into it if you want, but I will also design some "patch hats" (one for each supported board) which will be PCBs with pin headers to plug into the patch pincushion to connect the 1-2-3 headers, the QuickStart header and the 40-pin Propeller header to whatever FPGA board you have, in a useful way.

Thanks for all the good ideas, guys!

===Jac