So far, I have been shooting in the dark trying to get the Disk ][ emulator to work. I have no way to tell what the Apple IIe is getting as data. Here is some AppleSoft BASIC code I wrote last night (using a Beneath Apple DOS machine language program as a guide) to see what the bytes the controller card is getting. BASIC doesn't appear to be fast enough to get more than a few bytes per 'rotation' of the disk, but at least I can get a general idea of whether I am sending any valid data over. I am using this to experiment with different SPI clock speeds and byte formats.
10 SLOT6 = 49376: REM $C0E0 20 DRIVE1 = PEEK (SLOT6 + 10) 25 REM DRIVE2 = PEEK(SLOT6+11) 30 REED = PEEK (SLOT6 + 14) 40 DRIVESTART = PEEK (SLOT6 + 9) 50 DIM BYTES(255) 52 FOR X = 0 TO 254 54 BYTES(X) = PEEK (SLOT6 + 12) 56 REM IF BYTES(X) < 128 THEN X = X - 1 58 NEXT X 60 WPROTECT = PEEK (SLOT6 + 8) 90 HOME 100 FOR X = 0 TO 254 130 IF BYTES(X) = 255 THEN INVERSE 140 PRINT BYTES(X); SPC( 2) 150 NORMAL 160 NEXT X 170 END