Wednesday, July 22, 2015

Hooked up fpga controller to Pertec D3422 drive for testing

Today I was extremely busy with other activities, such as my job, but I was able to get in to the workshop at 5PM and get a bit done.


I set up the testing area to verify voltages on the connectors before I hook them into my fpga board - fired up the disk drive and then probed the lines. No high voltages were present and no short circuits, so it was safe to hook the connectors to the Nexys2 fpga board and begin the next round of testing.

Connecting the 48 small connectors to the fpga board took time to get right, but by the early evening I was ready to put in some preliminary vhdl to the board and fire it up. The intent was to watch the status lights and seven segment display to see if the status appears correct.

It became obvious that the termination resistors weren't connected to +5V inside the disk drive, thus not pulled up as they should. I know which connectors on the interface card carry these voltages, so time to trace out what I need to do in order to fire up the termination properly.

I haven't finished all of the logic I wanted, but put enough in to try a few commands. Specifically, I could start or stop the drive, command it to do an emergency unload of the heads, and ask it to seek to a given cylinder or the home position. Once the terminator pullup power is in place, I can give it a try.

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