English Amiga Board - View Single Post - Cyclone 20 - idea for homemade USB-based floppy controller (Catweasel-ish)

RichAplin · 28 November 2008, 21:01

Hiya,

I'm gathering most of my guff in
http://docs.google.com/Doc?id=dgddtc7_102gbzr2mgr
which people are welcome to edit or whatever.

In short:

FDI file format
Yes, cool, looks totally competent and the low level bitstream thing looks fine. Either me or someone can write code to read and write that format for interchange with other programs if required. Same with IPF etc.

Connecting real drive to WinUAE as DF0 is either fairly easy or extremely complicated depending how accurately you want it emulated. Naturally the answer is "perfectly emulated please", which sounds a bit tricky off the top of my head. Essentially you're trying to connect an emulated machine running in pseudo-time (under a task-switching OS) via several pieces of software and hardware with variable latency to a piece of plastic spinning at 300RPM.
Hm. Inherently tricky, but probably not impossible. I think I'd let that one sit on the back burner for a while.

Joysticks are easy. The CPU has ridiculously programmable I/O pins and can do anything required to read a stick and send it back via USB along with disk data. You could repurpose a regular PC USB joystick controller chip if you like, really then it's a separate project to Cyclone.

Weak bits etc:
I had some thoughts about this (i.e. what they actually are), and I found some Atari ST hackers on a forum who seem to think much the same thing, so maybe we're both right. Basically I kinda think it's most likely to simply be PLL confusion on readback, and juuuust possibly deliberate generation of wonky fluxes by sending too many transitions too close together when writing. See doc.

What people can do to help
Make your own!
Well, I'm waiting on my ARM boards to arrive in the post from the Ukraine right now. I believe they're the right tool for the job but I can't guarantee it of course. If anyone wants to buy one so they can build a Cyclone20 at the same time as I do, please do, that'd be great. (ebay store link in the document) You could also wait a bit until I've had some tangible results probably in week or two; up to you.

I don't expect building it to require anything else that isn't available from your Radio Shack/Tandy/Whatever, but we'll see - maybe $5 of other bits and pieces depending what options you want. Programming the initial firmware into the ARM board may require a $15 "JTAG Wiggler" but I'll let you know on that. There shouldn't even be any unusually fiddly soldering.

If it turns out lots of people are interested we can ask the nice Ukraine person if he'll pre-flash boards with our firmware before he mails them out.
Once the initial ARM flash is done I think we can reprogram them via USB, so we can load different firmware into the device as required.

Helping with software
I'm totally up for people helping with either the PC or ARM software, all we really need to do is make sure we wire the same chip pins to the same disk drive pins so our hardware is compatible, and I guess I'll lead on that one.

So probably nothing to do for a week or two while I get the basics fired up, but once I have, I'll start a sourceforge project and we can all get stuck in.

Dig up old amiga disks
I actually (gasp) don't have an amiga, any amiga disks (I think) or anything much like it. I think I have a low density Mac floppy somewhere. Anyway, I have a couple of PC floppys and that'll do for now. It would definitely be useful if a couple of people with a decent stash of Amiga disks were to build/obtain a prototype Cyclone20. Perhaps when I get the basic circuit done we can hand-make two or three of them and mail them to those who refuse to pick up a soldering iron.

Making PCBs for a real product
Someone with appropriate skillz is welcome to do this and sell them when the time comes. Probably won't be me but I'll put a schematic and pics up and I imagine some other interested community members will make their own in parallel to me.
Other things: This is a homebrew project, hooking up a 1541 disk connector or a C64 cassette deck or (nod to Clive Sinclair) running a nuclear power station should all be straightforward.

Super hardcore version for recovering screwed up disks:
Looking at the floppy drive in my hand, I can frickin _see_ the head pickup read lines... ooh now if those babies had a 20MSPS low-noise ADC on them, you could really have a serious pop at reading bad disks. Would be good to have a drive with double-resolution head stepping too. Actually a floptical drive would probably kick ass at this... aaanyway..

28 November 2008, 21:01	#30
RichAplin Registered User Join Date: Oct 2008 Location: san francisco/usa Posts: 176	Hiya, I'm gathering most of my guff in http://docs.google.com/Doc?id=dgddtc7_102gbzr2mgr which people are welcome to edit or whatever. In short: FDI file format Yes, cool, looks totally competent and the low level bitstream thing looks fine. Either me or someone can write code to read and write that format for interchange with other programs if required. Same with IPF etc. Connecting real drive to WinUAE as DF0 is either fairly easy or extremely complicated depending how accurately you want it emulated. Naturally the answer is "perfectly emulated please", which sounds a bit tricky off the top of my head. Essentially you're trying to connect an emulated machine running in pseudo-time (under a task-switching OS) via several pieces of software and hardware with variable latency to a piece of plastic spinning at 300RPM. Hm. Inherently tricky, but probably not impossible. I think I'd let that one sit on the back burner for a while. Joysticks are easy. The CPU has ridiculously programmable I/O pins and can do anything required to read a stick and send it back via USB along with disk data. You could repurpose a regular PC USB joystick controller chip if you like, really then it's a separate project to Cyclone. Weak bits etc: I had some thoughts about this (i.e. what they actually are), and I found some Atari ST hackers on a forum who seem to think much the same thing, so maybe we're both right. Basically I kinda think it's most likely to simply be PLL confusion on readback, and juuuust possibly deliberate generation of wonky fluxes by sending too many transitions too close together when writing. See doc. What people can do to help Make your own! Well, I'm waiting on my ARM boards to arrive in the post from the Ukraine right now. I believe they're the right tool for the job but I can't guarantee it of course. If anyone wants to buy one so they can build a Cyclone20 at the same time as I do, please do, that'd be great. (ebay store link in the document) You could also wait a bit until I've had some tangible results probably in week or two; up to you. I don't expect building it to require anything else that isn't available from your Radio Shack/Tandy/Whatever, but we'll see - maybe $5 of other bits and pieces depending what options you want. Programming the initial firmware into the ARM board may require a $15 "JTAG Wiggler" but I'll let you know on that. There shouldn't even be any unusually fiddly soldering. If it turns out lots of people are interested we can ask the nice Ukraine person if he'll pre-flash boards with our firmware before he mails them out. Once the initial ARM flash is done I think we can reprogram them via USB, so we can load different firmware into the device as required. Helping with software I'm totally up for people helping with either the PC or ARM software, all we really need to do is make sure we wire the same chip pins to the same disk drive pins so our hardware is compatible, and I guess I'll lead on that one. So probably nothing to do for a week or two while I get the basics fired up, but once I have, I'll start a sourceforge project and we can all get stuck in. Dig up old amiga disks I actually (gasp) don't have an amiga, any amiga disks (I think) or anything much like it. I think I have a low density Mac floppy somewhere. Anyway, I have a couple of PC floppys and that'll do for now. It would definitely be useful if a couple of people with a decent stash of Amiga disks were to build/obtain a prototype Cyclone20. Perhaps when I get the basic circuit done we can hand-make two or three of them and mail them to those who refuse to pick up a soldering iron. Making PCBs for a real product Someone with appropriate skillz is welcome to do this and sell them when the time comes. Probably won't be me but I'll put a schematic and pics up and I imagine some other interested community members will make their own in parallel to me. Other things: This is a homebrew project, hooking up a 1541 disk connector or a C64 cassette deck or (nod to Clive Sinclair) running a nuclear power station should all be straightforward. Super hardcore version for recovering screwed up disks: Looking at the floppy drive in my hand, I can frickin _see_ the head pickup read lines... ooh now if those babies had a 20MSPS low-noise ADC on them, you could really have a serious pop at reading bad disks. Would be good to have a drive with double-resolution head stepping too. Actually a floptical drive would probably kick ass at this... aaanyway..