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Cx4 Pinout 
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Joined: Sat 01 Dec 2012, 01:50:23

Posts: 240
Location: Oregon, USA
Post Cx4 Pinout
I can't seem to find a pinout of the Cx4 coprocessor, so I've traced it out for myself. I have 78 of the 80 pins traced, and the other 2 are tied to ground on both official boards, so I'm not really sure what they do... anyway:

A0..23, D0..7, RD, WR, RST, etc. are connected to the cart edge
RA0..20, RD0..7, ROE, RWE, RCE, etc. are connected to the ROM
RCE1 is CE on the first ROM if 2x8Mbit ROMs are used, or the only ROM if a 16Mbit ROM is used
RCE2 is CE on the second ROM if 2x8Mbit ROMs are used
SRCE is CE on the SRAM chip (never used on official games)
Code:
    1   A3     21  A15    41  RA8    61  /IRQ
    2   A4     22  A14    42  RA7    62  D7
    3   A5     23  A13    43  RA6    63  D6
    4   A6     24  A12    44  RA5    64  D5
    5   A7     25  SRCE   45  RA4    65  D4
    6   A8     26  RCE1   46  RA3    66  Vcc
    7   A9     27  RCE2   47  RA2    67  D3
    8   A10    28  RA19   48  RA1    68  D2
    9   A11    29  RA18   49  RA0    69  D1
    10  GND    30  RA17   50  GND    70  D0
    11  XIN    31  Vcc    51  RWE    71  Vcc
    12  XOUT   32  RA16   52  ROE    72  RST
    13  A23    33  RA15   53  RD7    73  GND
    14  A22    34  RA20   54  RD6    74  ???
    15  A21    35  RA14   55  RD5    75  ???
    16  A20    36  RA13   56  RD4    76  RD
    17  A19    37  RA12   57  RD3    77  WR
    18  A18    38  RA11   58  RD2    78  A0
    19  A17    39  RA10   59  RD1    79  A1
    20  A16    40  RA9    60  RD0    80  A2

Pins 74 and 75 are not internally connected to GND, but are tied to GND on the MMX2 and MMX3 PCB's. I have no idea what they're for, but they're probably inputs of some kind. Possibly one of them could be a Hi/LoROM switch like pin 10 on the MAD-1, but that is purely speculation at this point.

Pin 51 (RWE) is asserted low for writes to both the ROM and SRAM address space, so it can be used to write to reprogrammable ROM chips in-circuit, as well as writing to SRAM.


qwertymodo


Mon 15 Jul 2013, 12:30:10
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Joined: Sat 01 Dec 2012, 01:50:23

Posts: 240
Location: Oregon, USA
Post Re: Cx4 Pinout
I can't edit my original post, but pin 73 is ground, pins 74 and 75 are not, they must be inputs tied to ground. Not sure what they do.

Thu 08 Aug 2013, 19:30:42
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Joined: Sat 01 Dec 2012, 01:50:23

Posts: 240
Location: Oregon, USA
Post Re: Cx4 Pinout
I didn't like how the re-work was turning out on that RMX3 board... it probably would have worked fine, but I'm a bit OCD, and I didn't like that I had to re-work it. So I bought another cart, and decided to try something different using the chip off of the board I was re-working.

Image

Still needs the headers, but those are coming soon. I'm especially happy with how sharp the gold-plated logos and pin numbers turned out (the Nintendo one looks bad in the photo but it's very sharp and clear in reality), turns out soldermask is a lot more precise than silkscreen :)

byuu, I'll still get you your cart, I just want to play around with a few things first, and this will make it a lot easier for me to do so.

Thu 08 Aug 2013, 19:39:06

Joined: Thu 19 Nov 2009, 16:18:55

Posts: 1586
Post Re: Cx4 Pinout
That looks really clean and professional. Great work, man :D

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Thu 08 Aug 2013, 19:59:25
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Joined: Sat 01 Dec 2012, 01:50:23

Posts: 240
Location: Oregon, USA
Post Re: Cx4 Pinout
Thanks :) I like making things that look like professional, which is why the rework I was doing to salvage the RMX3 board was bugging me so much :P

Here's the back of the board, with decoupling caps, the feedback and series resistors for the resonator, and solder jumpers for the resonator pins (in case you want to use an off-board crystal) and also for pins 73-75, so you can either connect them to the header pins or just tie them to ground. If I'd tested the chip before ordering the boards, I'd have removed the jumper from pin 73 since it's an actual source ground pin. Also, the other 4 ferrite beads for the data lines are on this side (4 on top, 4 on bottom, just so they'd fit nicer).

Image

I have 2 more PCB's if anybody else wants one for any reason (OSHPark requires orders in multiples of 3). Unpopulated, of course, I don't just happen to have 2 more copies of RMX2/3 sitting around to tear apart ;)

Thu 08 Aug 2013, 20:17:29

Joined: Fri 10 Apr 2009, 15:00:08

Posts: 13668
Post Re: Cx4 Pinout
Hot damn that looks sharp!

And thank you. I'll cover the costs on the PCB and extra RMX3 cart as well, so no worries there.

Really appreciate the help. Really excited, I think this time it's definitely going to work out :D
Definitely looking forward to timing the program RAM cache, and fixing up the MMX2 intro sequence.

Thu 08 Aug 2013, 23:15:07
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Joined: Mon 20 Apr 2009, 08:11:50

Posts: 5266
Location: 日本
Post Re: Cx4 Pinout
Huzzah! That looks fantastic!

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Fri 09 Aug 2013, 05:31:43

Joined: Tue 30 Jul 2013, 15:33:32

Posts: 27
Location: Silent Hell
Post Re: Cx4 Pinout
Please, forgive my ignorance...

Will it ever be possible for programmers to take advantage of this co-processor?

Fri 09 Aug 2013, 16:34:01

Joined: Fri 10 Apr 2009, 15:00:08

Posts: 13668
Post Re: Cx4 Pinout
They already can in higan and on the sd2snes.

Fri 09 Aug 2013, 16:39:23
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Joined: Sat 01 Dec 2012, 01:50:23

Posts: 240
Location: Oregon, USA
Post Re: Cx4 Pinout
Does anybody know of any documents on the Cx4 in terms of programming for it? I'm building a perfboard setup to hook it up to a ROM, SRAM, and a Teensy++ in place of the SNES, but other than just poking around at various addresses with read/write commands to try to get SRAM working and see if writes to the ROM address space drive the data bus to the ROM properly (for writing to the ROM from the cart edge), I don't actually know how this thing works enough to actually try to DO anything with it...

Fri 09 Aug 2013, 20:19:23
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Joined: Sat 01 Dec 2012, 01:50:23

Posts: 240
Location: Oregon, USA
Post Re: Cx4 Pinout
Got the headers in from Samtec today. Ran up to Radio Shack to pick up a perfboard, and now I've started putting everything together. 2x4Mbit Flash ROMs (I won't bother with larger ROMs on this board, 4Mbit is the largest I can get in 5v DIP parts, and I wanted to use a JEDEC pinout on this board), and 256Kbit SRAM. Also, the Teeny++ as the host processor/PC interface. Everything is socketed, including the Cx4 daughterboard. I don't think I can get wire-wrap pins onto the ZIF sockets, so I'll have to manage with a mix of point-to-point soldering and wire-wrap. Which probably isn't too bad, since the ROM/SRAM pins aren't going to change, it's the Cx4 and Teensy++ connections that are likely to go through various changes, and they both have wire-wrap pins.

Image

Fri 09 Aug 2013, 23:59:24

Joined: Mon 01 Jun 2009, 21:57:44

Posts: 677
Post Re: Cx4 Pinout
Wow that board looks like a work of art, if that was Luke 50x50cm it could be hung on the wall

Sun 11 Aug 2013, 08:37:47

Joined: Tue 30 Jul 2013, 15:33:32

Posts: 27
Location: Silent Hell
Post Re: Cx4 Pinout
byuu wrote:
They already can in higan and on the sd2snes.


:/

I am well-aware that I'm a 'n00b' to your forum, byuu, but that was pretty vague.

Do you know of documentation, SDK, examples... anything available for developers?

Sun 11 Aug 2013, 16:40:41

Joined: Thu 19 Nov 2009, 16:18:55

Posts: 1586
Post Re: Cx4 Pinout
MarkGrass wrote:
Do you know of documentation, SDK, examples... anything available for developers?
http://wiki.superfamicom.org/snes/show/Capcom+Cx4+-+Hitachi+HG51B169

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My Emulator Repo for Debian/Ubuntu/Mint/etc (includes bsnes, Retroarch, libretro, VBA, Nestopia, Dolphin)

Sun 11 Aug 2013, 17:11:12

Joined: Tue 30 Jul 2013, 15:33:32

Posts: 27
Location: Silent Hell
Post Re: Cx4 Pinout
Thank You, hunterk. :)

Mon 12 Aug 2013, 04:54:23
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