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ChipMusic.org / Forums / Posts by nitro2k01
tRasH cAn maN wrote:I like my method better.
Reason? Bass and kick waveforms can be chosen independently and you can also make use of the PU1 sweep setting.my method has pictures (-;
But mine has (drum roll) a source file that you can download and have a look at.
Thanks for the advice! I'm fairly new to PCB design, so every bit helps a lot. I just add ground planes after routing because EAGLE won't render them on the fly, so it's tricky to organize things with them there.
There's a designated way of adding ground planes (or other planes for that matter.) If I remembered how to do it, I would explain to you here and now. 
The socket actually has to be a DMG socket if it's supposed to fit in the case, because of the way the DMG screws together both inside and out.
Hmm, I don't have a DMG open to compare with, but I'll get back to you on this one.
I'll look into the caps soon, I added the same number of extra caps to this board, but I should probably organize them a bit better.
It's good practice to have a big one near the power supply connection, and a couple of small ones spread out across the board, close to the other chips.
I really like your idea of having extra 5V and ground pads for modders, as well as the extra RAM. I hadn't thought of that at all, but yeah, it should be possible to use up to 64KB with all 16 address lines, correct?
Yeah, but then there would be no space for ROM, graphics memory or anything else. The idea is based solely on the fact that there's an unused area of "mirror" RAM, which basically means that if the two top bits are set (as they are for all addresses in the $Cxxx-$Fxxx range) the external RAM is selected. But the third highest bit is simply ignored, which means the same area is repeated. Actually, it's a little more complicated than that, since the highest 512 bytes, which would otherwise be in mirror RAM, are actually used for other things and don't reach the external memory bus.
Will you be releasing the EAGLE files under an open source or non-commercial use license? On the off chance someone tries to recreate the GameBoy processor with an FPGA, or tries some other complicated mod, having this board for a template would make things much easier.
Actually, that's what my comment about Jose and blackmailing was about. At least two people have made FPGA implementations of the Gameboy CPU. Then at some point, Jose got his "ultimate handheld" idea, which would among other things contain a real DMG CPU and a FPGA emulation of a DMG. So he turned to the creator of "FPGABoy", costis, and tried to make a deal. But as it also turned out, Jose had registered FPGABoy.com, which used to belong to costis, but expired, and used that as a bait to make him sell his design to him. Costis refused and never got his domain back. He also got cold feet and decided not to release FPGABoy as open source, which was his original long-term goal. So yeah...
Transplanting a SGB CPU should be way easier now too.
Yep, forgot to mention that.
I was thinking of a expanded RAM idea like nitro as well.
No, you didn't.
(Unless you actually knew about the mirrored RAM on $E000-$FDFF)
An odd feature I would like to see would be the VIN pin on the connector moved to some pads as well... I plan to experiment with this soon.
What are you trying to do? Since the Vin pin has very snug voltage range requirements, and only works if the program running on the GB activates it, I think you're better off injecting your signal into the post-CPU, pre-AMP part of the chain.
Jose gets his link ports manufactured for his Keyboard/Link port breakout board.
When (if) he's back you could strike a deal with him probably.
1) Those keyboard things don't even work properly. (At least not with the DMG style sockets they are using now.) They shouldn't have been manufactured in the first place. (But that's beside the point for this thread.)
2) Jose is a bit shady, and from my (well, not my personal) experience, he tends to basically blackmail people. I wish I didn't have to give this advice, but anyone considering doing business with Jose should think twice.
(Originally a response to 2xAA's post on 8bc, but also posted here in case that post would mysteriously vanish.)
gijs: I actually like my method better, since it makes use of the first step, and doesn't require it to be just a silent dummy note.
However, as a tech note, I think 3.7.4 still had the bug/feature where the volume envelope would always be retriggered when entering a note number, even when clearing the instrument, so for 3.7.4 I guess that method was needed.
NeX has actualy been discussing this very idea with me. Cool to see someone do it. Here's some advice:
Add ground planes. Ground planes help reduce interference and potential soft errors. The area around the crystal makes me worried, for example. Also make any power lanes slightly wider.
The display board has little springy contacts. These are ground connections, and you should ideally reserve an area that is not covered by silkscreen to allow them to connect.
The GBC cartridge socket has the ground pin moved one unit moved forward. This mean that the ground pin is the first thing that makes contact when inserting a cartridge, and the last thing that disconnects when pulling it out. This is good because it prevents latchup. Add another ground hole, so people can use a GBC socket if they so wish. (BTW, I know a couple of guys who have desoldered GB sockets of different kinds that I can hook you up with.)
Hint: If needed, you can internally rearrange any of the address pins that are in use on the internal RAM chips, and any of the data pins as well, if it helps the routing. As long as you can write a byte to a position, and get back the same byte from the same position, all is well. (This is not true for the cart slot, of course, where things already have their place.)
Hint: If it helps, you can rotate chips 45 degrees. Not only will the board still come out just fine, but most fab houses can solder components at non-90 degree angles as well, if you'd ever go that route. (Down to 5 degree increments or so, I think.)
You might be able to move the components on the headphone daughterboard to the main board, for those who want minimize the daughterboard. (NeX 
) The way I'd do it is to put a cuttable trace which bypasses those components, that you leave untouched if you don't want to connect those components to the main board.
Bypass caps are good - rather a couple uF too much than the opposite. Throw in a couple of ceramics as well, for good measure. (Regular common wisdom in electronics.)
A designated area with two extra holes for gnd and two extra holes for +5V wouldn't be wrong. Might come in handy.
Lastly, make sure that everything will fit, and no components will stick out too much etc.
Also, I have an idea for doubling the amount of available RAM, which would be possible if you could find a suitable 16 kByte chip, or fit two 8 kBytes on there. That would be very much of a "just because I can" type thing, and wouldn't actually be that useful, since no software supports it.
Also, if you're in for a challenge, you may want to try to redesign the power board, perhaps using MOSFETs for better speed and efficiency.
I'm sure I can come up with more things later, but I need to sleep. Would love to try this board out at some point.
Unless I completely misunderstood what you guys mean, my sav should do what you want. Click the link above.
This is very much possible. Gimme a sec and I'll upload an example to lsdsng!
Only at Google...
How does this correlate to TmEE's crystal audio mod? Can the "bad" PCB revisions be saved?
UNiX: Yes and yes.
Review here: http://chiptuneblog.blogspot.com/2010/0 … erich.html
That's that Feryl guy... The same guy who ranted about how chiptunes and swearing don't mix, named his album Winners Don't Use Drugs, doesn't get the pun in "Modemoiselle" and actually thinks it's a typo, and can't use tags on Blogspot correctly. Yeah, that guy.
"The artist formerly known as PDF Format"
ChipMusic.org / Forums / Posts by nitro2k01