2.8" QD Disk Emulation

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etaoin
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Re: 2.8" QD Disk Emulation

Post by etaoin » Wed Sep 18, 2019 9:01 am

As near as I came time it the error comes after exactly 16 seconds.

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Re: 2.8" QD Disk Emulation

Post by Jeff » Wed Sep 18, 2019 9:08 am

etaoin wrote:
Wed Sep 18, 2019 9:01 am
As near as I came time it the error comes after exactly 16 seconds.
~ 16 / 7.5 = ~ 2 rotations... This doesn't match with a write / check / write again / check again cycle. So i am not sure about the 2 write attempt...
Something interesting is happening i think !

etaoin
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Re: 2.8" QD Disk Emulation

Post by etaoin » Wed Sep 18, 2019 9:11 am

How about this for "interesting". This is very strange...
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etaoin
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Re: 2.8" QD Disk Emulation

Post by etaoin » Wed Sep 18, 2019 9:12 am

That is the Gotek trace
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etaoin
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Re: 2.8" QD Disk Emulation

Post by etaoin » Wed Sep 18, 2019 9:15 am

It looks like during a write you need to push out the written data on the RD line, and because it doesn't see that, it retries the write and gives up after the second attempt.

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Re: 2.8" QD Disk Emulation

Post by Jeff » Wed Sep 18, 2019 9:40 am

etaoin wrote:
Wed Sep 18, 2019 9:15 am
It looks like during a write you need to push out the written data on the RD line, and because it doesn't see that, it retries the write and gives up after the second attempt.
Yes !! This is exactly what i suspected : Two Write cycle back to back without a true "verify" at all !

This is maybe a rd data line issue, but i still suspect the ready line. i will have a closer look to the traces.

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Re: 2.8" QD Disk Emulation

Post by Jeff » Wed Sep 18, 2019 9:43 am

etaoin wrote:
Wed Sep 18, 2019 9:15 am
It looks like during a write you need to push out the written data on the RD line, and because it doesn't see that, it retries the write and gives up after the second attempt.
this wr to rd bridge was mentionned some thousand of posts above but i still really hope that this is not the reason because this is quite hard if not impossible to do this with this uC... Unless he just want some random data stream...


As i said above : This thing is crazy :!:

etaoin
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Re: 2.8" QD Disk Emulation

Post by etaoin » Wed Sep 18, 2019 9:48 am

This is the gotek capture data if you need it.

http://brodgar.technology/delivery/gote ... icdata.zip

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Re: 2.8" QD Disk Emulation

Post by Jeff » Wed Sep 18, 2019 9:58 am

etaoin wrote:
Wed Sep 18, 2019 9:48 am
This is the gotek capture data if you need it.
thx !

one thing you may try : disconnect the RD line from the Gotek and connect it to Write data to make a loopback. Then check if the Roland does 2 writes back to back or if it try to do a really verify after the first write.

etaoin
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Re: 2.8" QD Disk Emulation

Post by etaoin » Wed Sep 18, 2019 10:05 am

Jeff wrote:
Wed Sep 18, 2019 9:58 am
one thing you may try : disconnect the RD line from the Gotek and connect it to Write data to make a loopback. Then check if the Roland does 2 writes back to back or if it try to do a really verify after the first write.
Two write cycles. It won't match as RD needs to be inverted from /WD.

I'll throw in an inverter to see that that does.

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Re: 2.8" QD Disk Emulation

Post by Jeff » Wed Sep 18, 2019 10:13 am

etaoin wrote:
Wed Sep 18, 2019 10:05 am
Jeff wrote:
Wed Sep 18, 2019 9:58 am
one thing you may try : disconnect the RD line from the Gotek and connect it to Write data to make a loopback. Then check if the Roland does 2 writes back to back or if it try to do a really verify after the first write.
Two write cycles. It won't match as RD needs to be inverted from /WD.

I'll throw in an inverter to see that that does.
In fact i think that my ready signal trick isn't fast enough. I will optimize it.

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Re: 2.8" QD Disk Emulation

Post by Jeff » Wed Sep 18, 2019 10:15 am

And btw the motor signal "glitch" at the end is maybe to clear the ready signal... i maybe forgot this...

etaoin
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Re: 2.8" QD Disk Emulation

Post by etaoin » Wed Sep 18, 2019 10:15 am

No go with an inverter (just to rule that out)
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etaoin
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Re: 2.8" QD Disk Emulation

Post by etaoin » Wed Sep 18, 2019 10:19 am

Something I just remembered I wanted to check: the Reset line does go low straight after power up.
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Re: 2.8" QD Disk Emulation

Post by Jeff » Wed Sep 18, 2019 10:20 am

Jeff wrote:
Wed Sep 18, 2019 10:15 am
And btw the motor signal "glitch" at the end is maybe to clear the ready signal... i maybe forgot this...
Yes. This seems to be the case with the real QD drive : MO and RY are synced at the end of the write. This is the issue.
Let me add some ASM instructions in the code ;)

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