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Sorry about the bad pun...I am taking a computer networking class this term and the teacher has said token ring about 20+ times in 9 class periods. So, I got to thinking about how to implement such a design with logic. I spent today reading Introduction to Digital Design and messing around with the new Aldec Active HDL I had to download (due to the student version expired 1-1-14). I got a token ring simulation working on the PapPro and logic start wing. Each switch represent a network connected to the ring. If the switch is up the network wants to transmit. When the led above the switch is on the network has the token and is transmitting. If the switch is down the token is passed quicker. The token is placed in the ring by the up joystick and pressing the joystick like a button resets the whole ring(without a token). I spent about 8 hours messing with this. It just looks like a glorified Larson scanner though (if all switches are up). Oh well.

One interesting thing I learned from it is that if you time it right and put 2 or more tokens into the ring (by pressing up again) and all the switches are not up, one token can catch the other one and it gets destroyed or less often both tokens get destroyed. I don't know if this is how it would work in a real token network since they only have one token, maybe it is just a flaw in my design.

I used lots of D flip flops, some pulse extenders and clippers, a clock divider with fast and slow output, and a lot of or and and gates.

Check it out if you have the papilio pro, logic shield and papilio loader handy and want to see some flashing leds respond to switches.




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I am not sure if this is the problem, but I left out the part about the loader. Put the file in the Taget .bit file box and where it says Write to: select FPGA from the drop-down menu.


I don't know how to make a bit file that can use the spi flash. I didn't think anyone would want to use this bit file that way. I figured it was kind-of a "one and done" thing. After all, how many times can it be entertaining. One will probably do it.


I would love to learn how to save the bit file to the board and have it work. Is there a tutorial on how to enable the spi flash programming? I use VHDL and the schematic drawings mostly. Is the spi flash only for the Zap code users? I will look around on the forum, someone must have posted something. :)


Anyway, I hope the bit file will work for you now. If not just post again and I'll send you the project or something. Thanks for checking it out. 

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