Connecting IDE disks & ISA (network) card to Dreamcast

[OzOnE]

Oh, here's some extra info on connecting the IDE cable...

I just chose whichever Ground pad was closest, but you can basically choose whichever Ground is easiest.

But, the P.GND pins are meant to be used for Power Ground. So, naturally these should be connected to your CF / HDD power GROUND return.

The DC PSU could probably handle 1Amp or so on the 12V line for spinning up a 3.5" drive. Any more than this then it might explode.

A standard laptop 2.5" drive only requires 5V and around 600mA, so should work fine.

A CF card generally only needs a couple of hundred milliamps at most, so is fine. My CF card is 5V, and seems to be working OK.

btw, it's not confirmed whether the HOLLY is fully 5V tolerant, but the G1 port has some series resistors to help with this.
AFAIK, the VA0 boards had a 5V BIOS, so it's probably OK. Again, this is all at your own risk.

EDIT: I just checked the VA0 schematics and realized that the VA0 5V BIOS is connected directly to the HOLLY.
It looks like the resistors on the G1 port were just for limiting the current to the GDD (it uses 3.3V logic).

In other words, it should be fine to use a 5V CF / HDD and the resistors offer some extra protection.

Код:

IDE/ATA...          DC G1 port...
1. /RESET           A2
2. GND              A8
3. DD7              A4
4. DD8              A5
5. DD6              B4
6. DD9              B5
7. DD5              A6
8. DD10             A7
9. DD4              B6
10. DD11            B7
11. DD3             A9
12. DD12            A10
13. DD2             B9
14. DD13            B10
15. DD1             A11
16. DD14            A12
17. DD0             B11
18. DD15            B12
19. GND             B8
20. Key             (NC)
21. DMARQ           A14
22. GND             A13
23. /WR             B14
24. GND             B13
25. /RD             A15
26. GND             A18
27. IORDY           B15
28. CSEL            (NC)
29. /DMACK          A16
30. GND             B18
31. INTRQ           B16
32. /IOCS16         (NC)
33. DA1             B17
34. /PDIAG          (NC)
35. DA0             A19
36. DA2             B19
37. /CS0            A20
38. /CS1            B20
39. /DASP           (/ACTIVE LED)
40. GND             A21/B21


DC G1 port POWER...

A1/B1 = 3V3
A3/B3 = 5V
A25/B25 = 12V

A24,B24 = P.GND (Power Ground)

A8,B8,A13,B13,A18,B18,A21,B21 = GND


DC G1 port CDDA pins...

A17 = CD_EMPH (Emphasis)
A22 = CD_BCK (Bit Clock)
A23 = CD_SD (Serial Data)

B22 = CD_LRCK (Left / Right Clock)
B23 = CDDA_CLK (33.8688MHz master clock INTO AICA!)

OzOnE.