Gotek floppy drive emulator - Replacement firmware for better operation!

[TERRA Operative]

I have a good collection of TDS500/600/700 series scopes, and on a few of the nicer ones I installed the slim Gotek floppy emulators.
This is the specific model Gotek emulator in question:
https://gotekemulator.com/product/SFR1M44-DU26-Gotek-Floppy-Drive-to-USB-Emulator.html

I was never happy with their performance or reliability, so I decided to rewrite the firmware to make them work 'right'.
This firmware should work for any device the Gotek is able to be plugged into (with some caveats as to disk format stuff, coming updates will expand compatibility), not just the Tek TDS scopes.

It's really easy to convert your Gotek to the new firmware, all you need is a USB A to A cable and a jumper wire, and then after that firmware updates are a only USB stick away.

Check out my repository, it has a full step-by-step user manual with diagrams and all the info needed.
https://github.com/JaredCabot/tds-floppy-emulator


Let me know how you go with your USB sticks and scopes! Also feature requests and bug reports are welcome.

[TERRA Operative]

Updated to v1.1.0.

Added 720KB DD disk support.

https://github.com/JaredCabot/tds-floppy-emulator

[TERRA Operative]

Version 1.2.0 has just been released!

Changes:

Added:
- Status report. Holding both buttons writes EMUSTAT.TXT: firmware version and build ID, the unit's unique serial number and clock source, the internal disk's density and contents, health counters, the flash drive's file system, and the last transfer.

Changed:
- Faster transfers. A full 1.44 MB DATA IN takes about 15 s instead of 19 s; DATA OUT about a third less time (1 MB written and read back in 6.2-6.9 s instead of 10.6 s).
- Faster track loads.
- Smaller firmware: built with link-time optimisation.
- With no UPDATE.UPD, both buttons no longer give 2 quick blinks: they write the status report.
- Interface inputs no longer use the MCU's internal pull-ups.
- Crystal fallback: if the 8 MHz crystal fails to start, the emulator now runs from the internal oscillator instead of stopping, and the status report says so.

Fixed:
- Reads and writes beyond the end of the disk (sector 1440 on a 720 KB disk, 2880 on a 1.44 MB disk) are now ignored instead of reaching other parts of the internal flash.

Removed:
- The unused debug serial output.

Documentation:
- New general user manual, TFE-0002-00, for any equipment with a 26-pin slim floppy drive, with a technical reference (interface, timing, disk and update file formats).
- TDS manual revised.
- Hardware notes (docs/01): measured on a TDS 794D, the host drives SEL, STEP and DIR high enough to lift the board's 3.3 V rail to 3.8 V through the MCU's protection diodes; the fix is a series resistor on each line. Any firmware is affected, including the original as this is a hardware design fault.


https://github.com/JaredCabot/tds-floppy-emulator

[TerrySt]

Hi Terra,

Thanks for this project.  I have always struggled with the Gotek emulator.  It always took me a few tries to get a hardcopy saved onto a USB stick so that I could move it to my computer.  I have a TDS-524A that has had the Gotek emulator in it for a few years.  It works, but is clunky to use, so I am happy to see you are working on improving it.
But I am having trouble with the new firmware.  I got the base firmware loaded after a bit of trouble with USB cables, but after buying a USB-A to USB-A cable, I finally got through the procedure and it appears to be running with the base firmware.  I get a green LED when the scope boots up and the power on self tests all report passed.  But I cannot get it to save a file to the USB stick or read a file from it.  When I format the stick in the scope, it looks like it formats without errors, but it does not format it.  Files on the stick are still there (when I check it on my computer) after the format completes.  Trying to update the firmware fails also.
If I save the update file to the stick and try to load it, I get the solid red after three seconds, but then I get two rapid red flashes.  This is after having formatted the stick in the TDS-524.
If I place a small text file on the stick using my computer, and then try to read the stick with the emulator, I get six (I think) rapid flashes.  The file does not appear in the scope.
If I create a hardcopy on the scope, and try to save it to the stick, I see one red flash.  But nothing gets saved to the stick.
I have also tried formatting the stick on my computer (Win 10) as exFAT with Allocation Unit Size set to 512 bytes.

In short, I think I have the base firmware loaded, but the drive does not appear to read or write the memory stick.  Any suggestions would be appreciated.

EDIT:  I tried another stick (I have tried several) but now I was able to write a hardcopy file to the stick, but still can't read a file or format or update.  The difference is this is a smaller stick (16M) and I formatted it on my computer as FAT (which I think must mean FAT16).
On the stick is now a file I don't recognize:  INFOBR~1.OPM
This is what it looks like in notepad:
<?xml version="1.0" encoding="UTF-8"?>
<opml version="1.0">
  <head title="Info Browser">
    <expansionState></expansionState>
  </head>
  <body>
  </body>
</opml>


Thanks,
Terry

[TERRA Operative]

Hi,

The USB stick must be pre-formatted in a PC as FAT32 or exFAT (leave allocation unit size as default), formatting from the scope only formats the internal memory in the Gotek, it doesn't touch the USB stick.

To use the Gotek, perform whatever operations you need to on the scope (such as taking a screenshot saved to disk). This will put the file into the Gotek memory.

Then, insert your formatted USB stick (or you can put the USB stick in before the scope file operations, it doesn't matter) and press the button furthest from the USB port. This will copy the contents of the Gotek out to the USB stick and blank the internal memory ready for more data from the scope.
This essentially simulates you pulling a floppy disk out of the original drive and putting a new blank disk in.

To put files into the scope, insert the USB stick with files loaded into the Gotek and press the button closest to the USB port. This will load files into the Gotek memory, 1.44Mb at a time for each press, simulating you putting a new disk into the Gotek with each button press.

As a test  can you insert a formatted blank USB stick into the Gotek and press both buttons at the same time for 3-4 seconds until the LED flashes red?
This will put a text file with your Gotek's info on the USB stick, proving if it can work with that USB stick.
Post that file here for me to check.

If you see any red flashes at all without pressing a button, or anything but quarter second flashes for USB operations, let me know. You can compare to the error codes in the manual.


If you are still stuck, I can look into giving you some test firmware to nail down any USB timing issues (I only tested with the two Goteks and the USB sticks I have on hand).

[TerrySt]

Thanks.
There is some confusion on the buttons.  The manual you wrote says that the top button is the one that writes to the flash drive:
"Upper button (DATA OUT) Press and release: save every file on the internal disk to the
flash drive, verify them, then erase the internal disk."

and the lower button reads from the flash:
"Lower button (DATA IN) Press and release: replace the internal disk with the next
group of files from the flash drive."

with the buttons below the USB connector:
"a. Orient the emulator: Position the emulator in the bracket with its USB
port above the two buttons, as seen from the front of the instrument."

This is the same as how the Gotek firmware assigned the buttons.  But your response above reverses the button assignment.

Using the corrected button assignment you suggest, then I can get a file written to the flash. 

I was confused about the format operation.  I thought I could format the flash in the scope.  Thanks for clearing that up.  That was probably the main reason I wasn't able to get it to work.  (along with the button confusion).

I placed a blank, formatted flash into the scope and pressed both buttons for three seconds.  I am attaching the generated text file.  It says the FW version is 1.2.0, so maybe I was able to do the update. 

I will check some more tomorrow, but it looks like it it is working properly when I use a flash formatted properly on my computer.  I'll let you know if I find anything that doesn't work.  Again, thanks for taking the time to improve on the Gotek firmware.  It was a source of frustration before.

Terry

[TERRA Operative]

Let me check and correct the documentation...

Let me know how you go with it, like if there are any USB sticks that don't work or if there are any features etc you think are missing etc.



[edit] The documentation is now updated. The button description was indeed reversed. Thanks for pointing it out!

[edit2] Your EMUSTAT.TXT looks fine, from what I see there, your Gotek is working properly. 

[TerrySt]

Thanks.
Everything seems to work now.  The only thing that seemed strange is that reading the flash drive erases the files already in the emulator.  The manual explains that this is the case, and maybe there is a good reason for it.  I guess it is OK as long as I can remember to write the files to the flash before reading the flash.

The only other thing I wanted to mention in case anyone else runs into this issue is that when you flash the FW into the emulator for the first time, you need a USB A (male) to USB A (male) cable.  They are not that common (at least I didn't have one).  My computer has only USB C ports.  I tried three different types of USB C to USB A (male) cables and none of them would work.  They don't power the emulator.  I had to get a USB A (male) to USB A (male) cable and pair it with a USB C to USB A (female).  Then everything worked as expected.  I'm not sure all USB A male to male cables will work.  The web says that carrying power through from a male to a male is not a standard configuration and should not exist since it could be dangerous to use (potentially shorting two power sources together), but clearly it does.

The new firmware seems MUCH easier to use and more solid than the Gotek FW.  Thanks again.

Terry

[TERRA Operative]

The firmware is designed to act like a floppy drive in operation as closely as possible.

So when you load new data from the USB to the Gotek, it's like you are taking out the existing floppy disk in the disk drive and putting a new disk in (The USB stick is like a digital version of a floppy disk storage case, kind of...). This process erases the existing contents in the Gotek with the new data because you can't have two disks in one disk drive.

When you copy from Gotek to the USB, the data is moved to the USB and deleted from the Gotek. This presents an empty 'disk' to the scope, just like you had removed the current floppy disk and put a new blank one in ready for more data from the scope.


Unfortunately the maximum capacity of the Gotek buffer is limited to 1.44Mb.
I did investigate if the capacity limit was dictated by the disk drive or firmware, and it is a scope firmware/chipset thing. Nothing bigger than 1.44Mb is supported and only at floppy drive speeds, there's no way to make it faster from the scope out to the Gotek.
2.88Mb ED is present in the firmware at a superficial level but it is not implemented at all, so the only two options that are actually supported by the scope are 720Kb and 1.44Mb.