Michał Pleban wrote: > This is the DISK_RD signal without any cable: > http://i66.tinypic.com/257g7f6.jpg > > Here it is with 30cm cable attached: > http://i67.tinypic.com/w86k4w.jpg > > As you can see, the rising edge of the signal trails off a bit longer. > This is even more visible with a 1m cable: > http://i64.tinypic.com/2r5u79w.jpg > > Here it is really bad. I understand that the signal rises more slowly, > thus the decoder sees logical "0" longer than it should and throws errors. Problem solved. I was thinking on it and the signal looks pretty much like an RC delay. As if the drive was pulling the data line high with a resistor, but the cable introduced some capacitance. So I decided to pull the line up with 150 Ohm and voila, the signal improved: http://i66.tinypic.com/334nnn7.jpg Not enough for the chip to read without errors, so I added another resistor in parallel making it 75 Ohm, and it's even better: http://i63.tinypic.com/161axok.jpg Now the drive reads everything fine with a 1m cable! For 3m cables, I guess I would need 30 Ohm or something. So in the end, it was really termination. I was just using too high resistors when I tried that in the beginning... Regards, Michau. Message was sent through the cbm-hackers mailing listReceived on 2016-03-03 21:00:12
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