Info: FF with 26-pin header Gotek Floppy

[JoanMCD]

I sucessful use FF with an 26-pin header Gotek Floppy and use it in my Tektronix TDS3000 series (TDS3012B) Oscilloscope. The PB and the LEDs are at the same pins. I have to remove the resistors RA & RC (normaly 0R), and (not sure if it's nessesary) I also removed RB and the external EEPROM (8pin SOC). The PCB No. of the GOtek is SFRC2D. Model: Slim drive - SFR1M44-DU26 GOTEK.

Thx for the great project!

[keirf]

Do you know what RA, RB, RC (all 0R?) do or how they are connected into the Gotek schematic, and why you had to remove them? If I can document that I can add something to the "Gotek Compatibility" section of the wiki.

[JoanMCD]

Yes, all are assembled with 0R. With RA the drive ever shows 'Upd' on the display. The drive is mounted now, I can't measure the Rx->pin config. But I have a fast drawing on paper - maybe I can re-read it from there.

From here we can know that RA is pulling down Pin 37 of the STM32
Over all, the info is that by removing the resistors the 26-pin drive is also usable.

[keirf]

Added a link to this ticket to the wiki.

[JoanMCD]

[presslab-us]

Thanks for the info, I was able to get the SFR1M44-DU26 working on my LeCroy LC684 oscilloscope. I only removed the three resistors and left the EEPROM.

[mbirth]

Did it not work before? I have the SFR1M44-DU26 happily working in my TDS784D without any modifications. Just curious as to why you guys modded your disk emus.

[oldtrusty]

I also have the SFR1M44-DU26 26 pin version and having trouble getting the oscope to recognize my USB stick. Currently have the RA, RB, & RC 0R resistors removed. Only jumper in use is the S1 jumper on the rear header. I have successfully upgraded the firmware to FF and tried v3.9a and 2.13 with the same results. My scope constantly gives me a message to insert floppy disk, which leads me to believe that my USB stick is not properly formatted. You can see in the pic that my oscope finds the drive ok and lists the directory screen. It just won't read my files (previous oscope screen captures while using the floppy drive) that I placed on the disk for testing. I have tried a 1Gb and 2Gb stick formatted into (99) 1.4Mb disks. Looking for some assistance in how others who successfully got this working and how you all prepared your USB drives and what image settings you used. To this point I have tried every option in FF.CFG (placed in the root directory) with no success. Also tried removing serial eprom - no difference. The USB drive does however increment/decrement the virtual floppy disks when I press the front up/down buttons. I can see the LED inside of the USB drive and the ones on the emulator give feedback when I try to access the drive. So it seems to be somewhat working. See attached photos. Any help on this would be greatly appreciated.

[mbirth]

IMHO the original firmware of the SFR1M44-DU26 works better. With no USB device connected, it uses the internal flash memory as a virtual disk. Once you've connected a USB device (one large partition formatted to FAT32) and press the right button, it'll then read the first few files (up to 1.44 MB) from the USB and present those as the "disk". Pressing the button again will read the next few files and so on.

And if you want to store files on USB, just press the left button and from that moment on, all files written to the "disk" will end up on the USB drive. No need to make multiple disk images or special partitions or anything.

[JoanMCD]

The Tektronix TDS3000 series have a 26pin flat wire, so to use the SFR1M44-DU26 is a logic step. The original FW offers only a non HD Disk - what was not accepted by (my) TDS, so to replace the FW to get a HD drive was the next logical step.

[JoanMCD]

@oldtrusty I see a lot of markings on your PCB, and also a TO92 Transistor - ... As i remember, at the end I didn't need such modifications.

[oldtrusty]

@mbirth do you have the original firmware or know of a link to it?

[oldtrusty]

@JoanMCD the markings were to help me identify the boot0, +3.3, Tx, Rx, and Gnd pin during programming of FF. The TO92 (2N2222A) is temporary and was to replace the 1P SOT23 (2N2222A), which I damaged when I was playing with the rear jumpers. It tells the uC that the disk is read-only, I believe. That's the constant error I was getting when it was damaged. When I replaced the error went away.

How did you format your USB drive and did you have to load any of the .img files mentioned in the FF examples?

[mbirth]

@oldtrusty Sorry, no. Never fiddled with my Gotek and/or dumped the fw.

[kkwannyc]

Hi - fellow Flashfloppy user here with the SFR1M44-DU26. Mine was used with an IBM slimline floppy drive enclosure (formerly occupied by a TEAC FD05HF) to allow oldschool ThinkPads (560E) to work off disk images and whatnot. Mine has a revised logic board variant (SFRC2DA) that looks to be almost the same as the SFRC2D.

Just to confirm with the postings of @JoanMCD - you do have to remove/disconnect resistors RA and RC for the device to get out of flash update mode. Once it's removed the device will work just fine. Retaining the RB+EEPROM (used by the original firmware to...I don't even know what it does as this Gotek variant does not behave like normal Goteks, so formatting your drive into multiple segments of 1.44MB in size is not going to work)...is purely up to you. I disconnected RB but kept the EEPROM alone on mine.

Things to be aware of -

• The 26 pin FFC model runs on 5v, pins 1, 3 and 5 on the ribbon cable connector are power input rails (pin 1 is on the very left side of the FFC connector). If you need to run continuity checks between the 5v pin and the power, test pin 1 on the CPU (see below) with the 5v pin, and pins 1, 3 or 5 on the ribbon cable connector.

• the standard Gotek bottom pin-outs from the Flashfloppy modification guide will also work with this model...you would have to solder the pins on and check your work accordingly (see test point locations on the photo and described later)

[Boot0] [3.3] [TX] [RX] [RST]
[5v] [GND]

The following pins on the output corresponds to the following pinout on the STM32F105 LQFP64 package, and with the colors noted on the diagram below.

• The LQFP64 package contains 16 pins per side, 4 sides, and pin 1 starts on the bottom row on the left and proceeds counter-clockwise around the chip until pin 64 on the left side of the CPU on the bottom.

5v - Pin1 (VBAT) Red
Boot0 - Pin 60 (Boot0), Purple
TX - Pin 42 (J? next to J4, PA09), Green
RX - Pin 43 (J4, PA10), Blue

There is an AMS1117 voltage regulator(SOT223 package) with 3 pins, denoted on the board as U4. Left is GND, middle is 3.3v, and right is 5v.

On the SFRC2D/A the display connector is the following from left to right:

[SDA] [SCL] [GND] [3.3V]
SCL - PIn 29 (PB10) - Yellow
SDA - Pin 30 (PB11) - Orange

Ground is denoted as Black, and 3.3v is denoted as Orange-Red.

To program the SFRC2D/A with a USB-TTL serial adapter (preferably one that can do both 3.3/5v with the flick of a jumper), put a jumper between Boot0 and 3.3v, TX and TX to the correct pins, run VCC to the 5v pin (below J4), and ground to the GND pin (below RST), and follow the usual instructions.

There are existing test points on the board that can be used to verify that the soldering has been done correctly. See the attached photo for an idea of where they are located. Test points for RX/TX is above the STM105, Boot0 is to the left of the STM32F105, SDA/SCL is to the right (SDA will require you to test continuity with pin 27 directly), and 5v is present in at least 4 locations + the right leg off U4. 3.3v is supposed to be on the rightmost pin of the display pinout and on the middle leg off U4. @keirf you might find this photo of the SFRC2DA useful:

Hope this bit is useful for those trying to make this device do useful things - the SFR1M44-GU26 have practically no open documentation available whatsoever besides "buy this overpriced Gotek variant" and a poorly translated instruction manual of questionable applicability. @mbirth The default firmware is utterly useless crap if you plan to work with non-standard disk images, like the 1.72MB XDF images used by IBM's OS/2. For 1.44MB floppies it's not that difficult to grab a disk image template and have the FDC write/save it to a blank disk image, save it and then rename it on the USB stick later.

@oldtrusty did your model come with the jumpers for the bottom headers? I noticed that on mine the JD/JE headers were jumped...not sure if this might impact your Oscilloscope reading the device.