Larry McGovern Posted May 6, 2016 Report Share Posted May 6, 2016 What an outstanding board! Thank you Jack & Co.! My single goal in purchasing the Papilio Duo and Logic Start Shield was to learn about FPGAs and VHDL, and I would call this experience an unqualified success. I methodically went through Mike Field's PDF "Introducing the Spartan 3E FPGA and VHDL" and found it to be a very fast way to learn VHDL and the Xilinx tool sets. Mike Fields, if you are out there, thank you for that great guide! Your final chapter requests a postcard, and one shall be coming to you from California. Although the guide was written for the Papilio One development board, it works quite well with the Papilio Duo. The only chapters I did not do were Ch. 22 (A high speed external interface) designed for the Digilent Basys2, and Ch. 24 (Using an ADC) which uses the ADC chip on the Papilio One Logic Start wing. I probably could have interfaced with the AVR on the Duo with SPI, and might end up doing that anyway just for the learning experience. One thing to note: although Mike states that Ch 25 (Tri-State Logic) cannot be done with the Papilio One Logic Start Wing, it can be done on the Duo using the GPIO pins (which I didn't see referenced in the Logic Start Shield Hardware Guide, but are clearly on the board and schematic). Anyway, I highly suggest this guide to anyone else starting out who has either the One or the Duo. I'm figuring the next step is to learn how to use DesignLab, now that I'm a VHDL expert (ha ha) thanks to Mike. I'm no stranger to programming AVR microcontrollers, and the Arduino-like IDE is sure familiar, so it is now time to see what I can do with the two working together. A few general questions for the community: Are there any essential projects out there well suited for continuing my FPGA self-study? At this stage of my education, I'm more interested in the journey than the destination, but it would be nice to find a more involved project. I am fascinated by the ZPUino soft processor, but confess at this point I don't see the big picture here. Why would I want to recreate a processor on an FPGA, with so many cheap microcontrollers out there that do the same thing? Is it the novelty? Is the purpose to ease the transition to programming FPGAs for those who are more comfortable with software? Or is there some other larger purpose I'm missing? It looks compelling, but given that there is already an AVR chip on the Duo board, I think I might be inclined to use that instead, and interface the AVR with the FPGA over SPI. Speaking of interfacing with the AVR, I notice that the recommended way to interface is by setting it up as a Wishbone peripheral using the ZPU processor. Suppose I wish to do this without using the ZPU... Is there a recommended way to do this, without writing my own SPI interface from scratch? I know this must be an ignorant question, but I am still very much a beginner in the world of FPGAs. That's all for now. Looking forward to using this board in many future projects! Quote Link to comment Share on other sites More sharing options...
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