[SOLVED] Finding pinout of ASIC - Page 1
Forum section: electronics / beginners

author: tyguy2
author_rank: Unknown
timestamp: February 17, 2016, 05:12:16 pm
content: I've got a chip that I need help identifying. The label on the chip reads SEGA 315-5682. It looks like the chip attached, but has a different label. Can anyone find a pinout?

author: Skimask
author_rank: Super Contributor
timestamp: February 17, 2016, 07:18:44 pm
content: Ya, that's legible...

author: tyguy2
author_rank: Unknown
timestamp: February 17, 2016, 07:37:00 pm
content: Hmm, I'll try and get a better pic of it tonight.

author: Kilrah
author_rank: Unknown
timestamp: February 17, 2016, 07:57:27 pm
content: Maybe say what device it comes from?

author: tyguy2
author_rank: Unknown
timestamp: February 17, 2016, 08:00:08 pm
content: Whoops, sorry. This is coming from a Game Gear hand held (see this threadhttps://www.eevblog.com/forum/projects/converting-rgb-scart-to-vga/). It's the main processor unit. Specifically, I'm trying to find Pins D0 - D3, the clock, csync, and hlatch.

author: Kilrah
author_rank: Unknown
timestamp: February 17, 2016, 08:08:38 pm
content: Seems to be easy to find schematics of the GG but not of that version (VA4). Maybe the VA1 / first single chip version is "close enough" if you get lucky...

author: tyguy2
author_rank: Unknown
timestamp: February 17, 2016, 08:10:32 pm
content: The problem is that they basically changed the resistor layout in this version I'm borrowing a V1 from a friend to try and cross reference, but it doesn't seem to be the same.

author: McBryce
author_rank: Super Contributor
timestamp: February 17, 2016, 09:22:55 pm
content: The info on this site might help you:http://members.optusnet.com.au/eviltim/ggrgb/ggrgb.htmlMcBryce.

author: tyguy2
author_rank: Unknown
timestamp: February 17, 2016, 11:50:29 pm
content: Quote from: tyguy2 on February 17, 2016, 08:00:08 pmYeah, I mentioned that in this thread.

author: pmichel
author_rank: Contributor
timestamp: February 18, 2016, 04:28:25 pm
content: Found a clearer picture and a couple of other sites with some more information. Like Kilrah said, it's mostly for the other versions. If the LCD pads, connectors, or test points are the same you may be able to work backwards from them.http://www.smspower.org/forums/2539-GameGearTVhttps://console5.com/wiki/Game_Gear

author: Kilrah
author_rank: Unknown
timestamp: February 18, 2016, 07:58:52 pm
content: Time to whip the scope out and look for signals that look appropriate I guess.

author: tyguy2
author_rank: Unknown
timestamp: February 18, 2016, 08:02:20 pm
content: The problem is that I don't have anything to compare the signal to, and my scope is only 10 mhz, so I couldn't see the 32 mhz clock if I tried.

author: tyguy2
author_rank: Unknown
timestamp: February 18, 2016, 08:15:21 pm
content: Here is a picture of my exact chip

author: McBryce
author_rank: Super Contributor
timestamp: February 18, 2016, 08:22:55 pm
content: The clock signal can be found without a scope, just by following the traces from the crystal. The CSync should be easily viewable on even a 10Mhz scope.McBryce.

author: tyguy2
author_rank: Unknown
timestamp: February 18, 2016, 08:36:01 pm
content: Ok, I followed the traces, I think I found the clock pin. The screen freezes whenever I connect my probe to it, then un-freezes when I disconnect. Should I attach my clock pin directly to the crystal, or elsewhere?

author: McBryce
author_rank: Super Contributor
timestamp: February 18, 2016, 09:35:27 pm
content: I don't know the circuit, but if the clock is buffered with something like a 74HCU04 or whatever, then I'd take the clock directly at the output of the gate.What probe is stopping the clock? A properly setup 10:1 passive scope probe shouldn't knock the clock out.McBryce.

author: tyguy2
author_rank: Unknown
timestamp: February 19, 2016, 06:15:26 pm
content: I finally got the other board from my friend, I'll post my find later tonight on if the signals are a match.

author: tyguy2
author_rank: Unknown
timestamp: February 20, 2016, 09:04:02 pm
content: Alright, I figured out the Clock signal (and finished the project). It's labeled as C27.