Disk controller kit: Please insert disk

[John Kennedy]

When I use the monitor program to try and do, well, anything, all I get is "Please insert disk" over and over, no matter if I insert the disk or not. The drive motor spins up when expected, BTW.

This is on a system that once worked, but it had connections soldered directly to the Arduino (actually a different Arduino, this one is brand new) rather than via the nice neat interface board. (Another data point: the LED card works find when connected the AltairDuino).

I've tried two different floppy drives, and now two different disk controller kits. I get the same result: "Please insert disk"

What should I be testing to try and work out what is wrong? 

thanks

-John

[John Galt]

outside of the monitor can you read the disk under cp/m?

[da...@hansels.net]

The monitor assumes that no disk is inserted if it never sees a low-going pulse on the INDEX line,

i.e. it never detects the index hole on the disk after turning on the motor.

The INDEX signal coming from the disk drive is directly connected to pin 19 of the ATMega processor (U6)

so if you have an oscilloscope you could probe whether that pin regularly goes LOW. If it does then you likely
have a broken ATMega. You can also try and test continuity going from pin 19 of U6 to pin 8 of floppy disk
connector on the card to check for a cut trace. And of course test your cable.

David

[John Kennedy]

Thank you.

Pin 8 on the floppy disk interface is connected to pin 19 on the ATMega, via the ribbon cable (used two cables to be sure).

When a disk is inserted and the motor is spinning, there are NO pulses arriving at pin 19.

When I scope the optical sensor in the drive (it’s exposed in the TEACs) I see pulses.

¯\_(ツ)_/

Does something have to be happening for the pulses to appear at the disk interface?

Something obvious has to be messed up here.

[John Kennedy]

I think it might be a power issue - I am not using a regulator to provide 5v. Not sure why this would work before I used the breakout board, but hey. 

[da...@hansels.net]

The Arduino Due can provide the 5V - I would assume that the breakout board is set up that way.

The monitor shouldn't work at all otherwise since the ATMega328p on the board runs off the 5V.

The drive will not output any signals unless its SELECT input is LOW. The motor will run even
if the drive is not selected, so that could be a possibility. Check pin 14 (drive A) and 12 (drive B)
on the ribbon cable/drive. These are also visible on pins 3 and 2 on U8.

The schematics for the board are available here.

[John Galt]

just something that happened to me

are you using the disk ribbon cable that has the twist in the middle for the A: connector?

the reason i ask. when i first setup the disk drives, i completely forgot about the A drive ribbon cable twist. this was because newer floppy drives allowed you to change the jumpers and eliminate the twist.

so here i am with the wrong drive ribbon cable and its all pass through. i could not understand why it would read a disk. so i changed the jumpers to force it to ignore the change disk sensor.

then i could read the disk but i could not change the disk i had to power down everything and power back on.

then i remembered the ribbon cable that has the A drive twist. i replaced the cable and put the jumpers back and like magic it was reading disk change and loading the disk.

i felt dumb but its been like 30 years since i dealt with a floppy drive.

the floppy cables they sell on amazon are just pass through cables, you have to specifically search for the ones with the twist in the ribbon cable.

[John Kennedy]

Good idea, but that doesn't seem to be it.

* I've tested one end of the cable to the other, and traced the signals from the floppy disk to the right pins on the chips on the interface board.

* The monitor program launches, and I can stop/start motors, select the right drive (I've two connected), even step the heads in and out.

* The monitor program always reports "Please insert disk" when it does something such as reporting information that needs to know the speed. Putting a disk is not detected.

* My scope cannot detect a pulse at ATMega pin 19, nor on Pin 8 of the ribbon cable from the floppy.

* The drive select signals go high/low as expected.

* I built a second drive interface card as I was determined to rule out that I'd broken the first one. The results with it are identical.

* When I pretend everything is great and set up the AltairDuino to boot from floppy, the disk motor starts but there is no head activity (I don't have a known good boot floppy anyway, as the monitor program won't work to create one).

I've spent enough of my weekend on this for now, so I'll pack it away and maybe something will occur to me.

thanks for the suggestions though!

[John Kennedy]

[John Galt]

Something else.

When I first started with the 5.25 hd disks. I was messing with them in my pc first and I had 

Written data, when I went to use the disk controller on the back plane, I just figured I could stick the disk in

Run the monitor and write a disk. But it didn’t work.

I realized I needed to format the disk again fresh was using windows Xp with a good FAT

With a fresh format then I ran the monitor and it was happy and wrote the disk.

So after that I reformatted all my disks and then wrote them.

Of course then I found the issue of two drives that don’t like each other and had to swap drives around and change the track 0 calibration so that both drives played nice with reading the same floppy.

Grasping here obviously trying to help

[John Galt]

Just another thought. Since two cards act the same way and you know the cable is good then how close did you look at the drives themselves.

Are you using the FD-55GFR 5.25" drives or the 3.5" version same models as recommended, are the jumpers on the drives in the default positions?

these drives have a truly amazing number of configurations with the jumpers.

going back to power. I'm using 2 separate power supplies one for each drive housing. this was more for portability so i could swap them as single or double setups.

each power supply has an additional tap to run the Arduino through the rear board. again just in case i wanted to split the drives and have two single disk units.

I'm using the power regular on the backplane. 

One difference is since I'm not using the breakout board, i have hardwired the main power inputs for ground, Raw, 5V and 3.3V directly, 

My Arduino is getting its separate power. 

The back plane is getting its separate power I have it with its own Power switch for the 5V.

each disk drive also has its own separate power and i put them both on power switches with Fused protection, just in case.

I was worried with the setup so i wanted to try and isolate things incase there was a problem at least an easy issue(i hope)

[John Kennedy]

The drives are the TEACs and they worked before I moved to the breakout board, that's the crazy thing. Oh well, next time I've a free weekend I'll build a second breakout board and try it on another AltairDuino!

[John Galt]

a concern i had with the breakout board was bad connections with the pins. you start introducing more points of failure.

this was why i asked if there was a better method with connecting the back plane. really nothing unless you get a new main board from chris.

i don't know maybe go back to soldering the pins on the backside of the DUE and double check using the PDF i posted on where the wires go?

[John Kennedy]

I have checked all the lines, but clearly something isn't right, so rebuilding another PCB will be a quick and easy way to try again.

I would like to confirm which side of the PCB the ribbon cable should be connected to. I've not seen an image of the board built and working.