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Add license; finish README.
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David Given
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COPYING
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COPYING
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Copyright © 2007-2009 David Given
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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142
README.md
142
README.md
@@ -8,6 +8,45 @@ FluxEngine is a very cheap USB floppy disk interface capable of reading (and eve
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**Big warning.** Right now it is a hacked together prototype. It is not ready to use. Unless you eat and breathe embedded systems code and were born with a soldering iron in your mouth (hopefully, turned off) then this is not for you. If you were... please, give it a try!
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### Infrequently asked questions because nobody's got round to asking them yet
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**Q.** Why not just use a USB floppy drive? There are lots and they're cheap.
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**A.** Because USB floppy drives typically support a very limited set of
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formats --- typically only IBM 1440kB and 720kB. The FluxEngine should work
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on (almost) anything.
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**Q.** But aren't floppy disks obsolete?
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**A.** Absolutely they are. That doesn't mean they've gone away. Good luck
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with any old hardware, for example; a classic Mac won't boot without a
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classic Mac boot disk, and you can't make them on PCs (because they're
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weird). This is where the FluxEngine comes in.
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**Q.** But how can you read and write non-PC formats on a PC floppy drive?
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**A.** Because the FluxEngine hardware simply streams the raw magnetic flux
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pulsetrain from the drive to the PC, and then the analysis is done off-line
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in software. It doesn't rely on any floppy disk controller to interpret the
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pulsetrain, so we can be a lot cleverer. In fact, the disk doesn't even have
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to be spinning at the same speed.
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**Q.** That's awesome! What formats does it support?
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**A.** I'm glad you asked the question. Not a lot, currently.
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### Formats that it supports
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Currently, not a lot.
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- IBM MFM 1440kB and 720kB formats, a.k.a. standard PC floppy disks
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- Brother 240kB word processor disks
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...aaaand that's it. If you want more, please [get in
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touch](https://github.com/davidgiven/fluxengine/issues/new); I need samples
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of floppy disks to scan and play with.
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How?
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----
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@@ -81,9 +120,12 @@ Here's the physical stuff you need.
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bottom because there are components that stick out on the other side and
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the bottom needs to go flush against the drive.)
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3. **If you're using pins:** solder you 17-way pins to either side of the
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3. **If you're using pins:** solder your 17-way pins to either side of the
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board, from 0.2 to 3.0 inclusive.
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4. Optional: solder the ends of your floppy drive power supply cable to any
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convenient VDD and GND pins on the board. Remember to check the polarity.
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And you're done!
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### Building the firmware
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@@ -119,11 +161,65 @@ touch](https://github.com/davidgiven/fluxengine/issues/new).
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### Using it
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So you have client software, firmware, and hardware all ready. What next?
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So you have client software, programmed the firmware, and the hardware is all
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ready. What next?
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1. Attach the FluxEngine to your floppy disk drive. Pin
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1. Attach the FluxEngine to your floppy disk drive. Pin 0.2 is REDWC and
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connects to pin 2 on the floppy drive. Pin 3.0 is DSKCHG and connects to
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pin 34 on the floppy drive. All the other board pins connect in the
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obvious order. Odd pins on the floppy drive are left unconnected.
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The sampling system is dumb as rocks.
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2. **Important.** Make sure that a sacrificial disk is in the drive.
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(Because if your wiring is wrong, you'll probably corrupt the disk.)
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3. Connect the floppy drive to power. Nothing should happen. If anything
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does, disconnect it and check step 1.
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4. Connect the FluxEngine to your PC via USB --- using the little socket on
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the board, not the big programmer plug.
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5. Do `.obj/fe-rpm` from the shell. The motor should work and it'll tell you
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that the disk is spinning at about 300 rpm. If it doesn't, please [get
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in touch](https://github.com/davidgiven/fluxengine/issues/new).
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6. Insert a standard PC formatted floppy disk into the drive (probably a good
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idea to remove the old disk first). Then do `.obj/fe-readibm`. It should
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read the disk, emitting copious diagnostics, and spit out an `ibm.img`
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file containing the decoded disk image (either 1440kB or 720kB depending).
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7. Success!
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### The programs
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The FluxEngine client software is a largely undocumented set of small tools.
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You'll have to play with them. They all support `--help`. They're not
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installed anywhere and after building you'll find them in the `.obj`
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directory.
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- `fe-inspect`: dumps the raw pulsetrain / bitstream to stdout. Mainly useful
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for debugging.
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- `fe-readbrother`: reads 240kB Brother word processor disks. Emits a
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256-byte-sector FAT filesystem. (You can access this with mtools although
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you'll need to edit the media type bytes in the boot sector and change
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them from 0x58 to 0xf0.)
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- `fe-readibm`: reads 720kB or 1440kB IBM MFM disks. Emits a standard
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filesystem image.
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- `fe-rpm`: measures the RPM of the drive (requires a disk in the drive).
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Mainly useful for testing.
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- `fe-seek`: moves the head. Mainly useful for finding out whether your drive
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can seek to track 82. (Mine can't.)
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- `fe-testbulktransport`: measures your USB throughput. You need about 600kB/s
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for FluxEngine to work. You don't need a disk in the drive for this one.
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### How it works
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It's very very simple. The firmware measures the time between flux transition
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pulses, encodes them, and streams them over USB to the PC.
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There's an 8-bit counter attached to an 12MHz clock. This is used to measure
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the interval between pulses. If the timer overflows, we pretend it's a pulse
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@@ -139,15 +235,13 @@ rollover at 21us.
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data difficult to analyse, so 12 was chosen to be derivable from the
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ultra-accurate USB clock.)
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VERY IMPORTANT:
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Once at the PC, we do some dubious heuristics to determine the clock rate,
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which depends on what kind of encoding is being used, and that in turn lets
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us decode the pulsetrain into actual bits and derive the raw floppy disk
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records from there. Reassembling the image and doing stuff like CRC checking
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is straightforward.
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Some of the pins on the PSoC have integrated capacitors, which will play
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havoc with your data! These are C7, C9, C12 and C13. If you don't, your
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floppy drive will be almost unusable (the motor will run but you won't see
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any data). They're easy enough with some tweezers and a steady hand with a
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soldering iron.
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Some useful numbers:
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Some useful and/or interesting numbers:
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- nominal rotation speed is 300 rpm, or 5Hz. The period is 200ms.
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- a pulse is 150ns to 800ns long.
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@@ -164,6 +258,26 @@ Some useful numbers:
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Useful links:
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http://www.hermannseib.com/documents/floppy.pdf
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- [The floppy disk user's
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guide](http://www.hermannseib.com/documents/floppy.pdf): an incredibly
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useful compendium of somewhat old floppy disk information --- which is
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fine, because floppy disks are somewhat old.
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https://hxc2001.com/download/datasheet/floppy/thirdparty/Teac/TEAC%20FD-05HF-8830.pdf
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- [The TEAC FD-05HF-8830 data
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sheet](https://hxc2001.com/download/datasheet/floppy/thirdparty/Teac/TEAC%20FD-05HF-8830.pdf):
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the technical data sheet for a representative drive. Lots of useful
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timing numbers here.
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Who?
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----
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The FluxEngine was designed, built and written by me, David Given. You may
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contact me at dg@cowlark.com, or visit my website at http://www.cowlark.com.
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There may or may not be anything interesting there.
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License
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-------
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Everything here is licensed under the MIT open source license. Please see
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[COPYING](COPYING) for the full text. The tl;dr is: you can do what you like
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with it provided you don't claim you wrote it.
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