Embedded / audio nut asking about Papilio


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Hi. My name is Steve. I am a mature(=old) audio systems student. I discovered embedded systems about 2 years ago starting with the ubiquitous Arduino. I am interested in FPGA as I have heard it is possible to do some very nice sound synthesis using these devices. I have some experience using Arduino and programming Microcontrollers in C and even less, Assembler.

I know FPGA is a completely different platform than MCUs and uses a language called VHDL or Verilog ( or schematic .) One thing that impresses me about FPGAs is the fact that an FPGA program is essentially whole. In other words, turn it on and it IS what you have made it do. At the moment I see an analogy with one of those pin matrixes where you push your hand on the bed of pins and the pins retain the shape of the hand. I like this analogy although I could be wrong...

I am thinking of getting a Papilio one board, I have looked at the options and I see there are two boards. One 250K and one 500K.

If I wanted to learn audio and synthesis programming and effects, maybe using MIDI or even Open Sound control and maybe touchscreen interfaces, would the Papilio One be suitable for this? Oh and what about wireless capability.?

My budget at the moment would allow me to buy a 250K board and the Logic Starter board which I would probably order from the gadget factory store as it is cheaper than SK Pang ( I live in London UK.)

Any help appreciated,

thanks peeps.


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Hi Steve,

There is a lot you can do on the 250k for Audio projects, but as it only has a small amount of RAM the scope for DSP-style effects (reverb etc) are limited. Compared to a microcontroller (e.g. Arduio) it has a huge scope for weird and wacky sound synthesis - as projects like the Retrocade and the chip-tunes demonstrate. MIDI in/out is pretty simple (it's just a serial protocol after all...), Plenty of scope for things like an ultrasounic distance sensor to MIDI interface.

One thing that Papilio can do that micro-controllers can't is generating high quality digital output. .(see http://hamsterworks.co.nz/mediawiki/index.php/SPDIF_out for an example).

In-line audio processing is possible too - for example you could build an all-digital active speaker crossover to split out high and low frequencies.

But a rule of thumb might be "Writing software is 10x quicker than designing equivalent hardware, so unless you want to chew through your time use a micro-controller (or an FPGA with a soft CPU like the ZPUnio or AVR8) if at all possible".

As for wireless, it should be possible to use any wireless modules that works with Arduino - just do a quick search for "Arduino WIreless" on http://dx.com for examples. Of course you may need to port the driver across too!

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Hello Steve,It sounds like what you really want is our newly released RetroCade Synth hardware. We've been doing a LOT of work with FPGA audio, this is the platform we are doing it on and we expect to do a lot more. We eventually want to make a lot of different FPGA synths work on the RetroCade Synth and the best part is that we use the ZPUino Soft Processor to implement most of the functionality. The ZPUino uses a modified version of the Arduino IDE so it makes the it much, much easier to get started with an FPGA and would be something you would be very comfortable with.

The Papilio Pro and the RetroCade MegaWing is the recommended hardware combination but if you don't mind losing SD card and MOD file capability then all the rest of the synth stuff will work with the Papilio One 500K and RetroCade MegaWing.

For wireless, I have a WIFI wing that is already designed and sitting on my desk waiting to be tested. The end goal is to use it with the RetroCade to make wireless dashboards for the Ipad and Android tablets.


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Hi guys and thanks for the head up. I do like the sound of the retrocade synth wing.

Couple of questions though..

1. I see there is a bit file to emulate the SID & Yamaha chips but supposing I wanted to start my own synthesis project from scratch not nessesarily using these chips... is there a good learning base for this? What would be the best way...

2. Also, with the Papilio I understand I can use an Arduino style environment but are there other IDEs I could use?

3. Cheekily, I am on a budget and to buy the 500K Papilio and a retrocade wing would cost me approximately $119 plus shipping to the UK...could I get any kind of reduction on that?

( I am a student!! (he says shyly..))

4. Have you seen Scott GravenHorst's site on FPGA synths and would the Papillio be able to be incorporated into his designs??

The webpage for Scott is here:


Thanks again peeple.xx

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Hey mubase,

I already have the GateMan Poly working on the Papilio, I'm working on getting it to work with the RetroCade hardware now.

We can work out a student discount if you are really serious about the RetroCade hardware. :) The only problem is that we have to wait until the next batch of boards is manufactured!


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Hi! Very nice paper from the Digilent contest. Thanks for all the info here guys.

I am interested. I have been having a look at xilinx boards on Ebay like this:


but I don't know if they would be good for a beginner to FPGA/CPLD and what kind of support they have. I do like the 4.3" TFT screen though.

Couple o questions...

By attaching the retrocade, does it mean that all papilio pins are taken & I can't expand beyond the shield..( i.e. what if I wanted to attach a 3.2" TFT..)?

secondly, when will they be back in stock?

and in the mean time, what would be the cost of a 500k board & a logicstart with shippin to the sunny old UK??

Thanks again. :)

brap brap.


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