Yet another Genesis/Megadrive mod - Video Selection board and Switchless Mod

I looked at the code and from what I can tell (again no expert but I can notice from the code some things) we could easily add another LED to it but will have to copy and edit parts of the code to have a functional LED.

 

@Helder, yeah I thought so, But it seems they are in a kind of cycle synchronized with the Language/Video.
I guess adding a new output (pin 7) and a condition or "a case of" to check if pin 5 and 6 are up then activate pin 7 and set the two others to 0 will work, but I don't know how to do it in ASM. :x

 

I made some edits to the ASM file to incorporate the extra LED and made it so it should turn on with a different Video Mode is set. I haven't tested it out on an actual PIC just ran it through a debugger to see if there was any major errors or issues. If your willing to test it out I can compile the HEX and I did set it up as pin 7 being the 3rd LED.

 

@Helder Can you also revert the logic of the LED? Since I'm using a 74LS00 I had to use common cathode LED. If I could get rid of the IC and keep my LEDs that would be great.

If not nevermind I'll buy common anode RGB Led.

I don't have the pic programmer yet (lot of unexpected stuff since last month. I had to buy a new fridge, and I now I must buy airplane tickets) so I won't be able to test it right now.

 

Daily update:

I don't think I can optimize more. It fits tight but everything is there. Good thing I've finished the board: I'm starting to see red/blue lines every time I'm closing my eyes!

The board without the remote is estimated at 10$ for 3 on OSH Park.
I need to make a separate file for the remote or else OSH Park will take a big empty zone of PCB.

Tomorrow I'll try to make a new reset-switch board.

 

After looking at the switchless MegaCD mod from mmmonkey here, I realized that the MegaCD bios used an invert logic signal than the one from the PIC. Mmmonkey used his hex inverter from his reset switch.
Instead, I will use the 74LS00.



Also for the reset board, I'll remove the 510k SMD resistor from the motherboard and put it on the reset switch. I'll let the choice of re-use the the SMD or put a classic resistor. Then you have to weld the switch board to the ground and the four headpin instead of the old reset switch.

 

Ok after some tests on OSH Park, I have to sperate all the boards to reduce costs:
- Video board: 10,20$
- Remote: 2.35$
- Switchless: 5.40$
- Reset: 2.10$

Total: 20.05$ (haven't check the shipping cost) for 3 boards of each, so around 6.7$ per console.

For now I'll print them and look how they fit in the Genesis.
I have to buy a GQ4X, then programm the PIC to test if everything is working on the board first and then I'll buy the boards.

 

Shipping is free from oshpark!

 

Just be mindful of the tabs left on the boards, that is the biggest complaint I have with OSHPARK and sometimes it can take a few weeks to get things.

 

Ho! Nice.

So what should I do? Add more space around each boards? Time isn't a problem.

Also, Seems the CXA1445 need a DIP-24-4 socket, and I don't have those -_-
I'm looking to buy them on Mouser but seems it's 7$ for 1 :x http://ca.mouser.com/ProductDetail/...GAEpiMZZMs/Sh/kjph1tvt1/mEPT/XoRL0vd%2bNbRZ4=
I found 1 sellers on EBay http://www.ebay.ca/itm/CN6-AUGAT-IC...384?pt=LH_DefaultDomain_0&hash=item2585695798

I think I'll just buy some round pinhead http://www.ebay.ca/itm/10Pcs-Single...174?pt=LH_DefaultDomain_0&hash=item1e76c5fad6 .

I've printed the circuits and glued them on a piece of pizza cardbox.
I'll post later some quick pics in the genesis.

 

After a quick view of the placeholders I noticed a couple of things wrong.

Quick overview (in centimeters)


All the placeholders in the Genesis


1rst thing wrong: the reset switch board overlap the audio boards. Dammit!


2nd thing wrong: the JP 1/2 and JP 3/4 are not at the same position between VA2/3/4 and VA5/6. I've blindly follow a VA5/6 board to design mine. Fail.


At least the video board is what I expected. The heatskin won't be over the trimm capacitors and the pins for the remote


The looong video board.


So I update the switchless board by adding a compatible mod for either VA2 to VA6. VA2/3/4 will use pins 1-4, VA5/6 pins 3-6

 

By 'tabs' I think Helder means that there's some extraneous board bits left over that aren't cut off smoothly. There's nothing to worry about with the design of the board, it just means you have to cut off (carefully!) some pcb cruft.

 

This is what I'm talking about:

 

Ho ok.

 

Boards ordered and already sent to fab.

Now, I'm looking to buy a GQ-4X + EPROM Eraser and an ADP-054.
What I don't understand is they are much cheaper on EBAY's MCUmall store than on the MCUmall website (all prices in $ CAD):
http://www.ebay.ca/itm/310345927515?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
http://www.ebay.ca/itm/310345943261?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
http://www.ebay.ca/itm/310531715847?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Total 144$ plus 20$ for shipping cost.

On MCUmall's website:
GQ-4x + eraser pack: 127.44$ (GQ-4x alone 105.84$, eraser alone 26.99$)
ADP-054: 31.32$
ADP-053: 1.07$

Total 159.83$ taxes included + 20.74$ for shipping.

There's 15$ between EBay on MCUmall's website, but on the other hand, I found the ADP-053 only on the website....

Mmmm....

 

I have GQ-3x with the tssop 44 adapter I'm trying to get rid of you you're interested. Send me a PM in interested.

 

No thank you.

 

Small update, OSH has sent my PCBs. Also, I bought the IC sockets... and the sellers sent them with wrong row spacing. I've already got my money back, but now I have to buy them somewhere else. :/
Sorry for the lack of updates.

 

Update:
I have bought my GQ-4X with some adapters.



So I immediatly plugged it and program my very first PIC!
Some modifications on my test board and voilà!:



It works! I know it's not something complicated but I'm happy that everything is working.
I'm still waiting for the board from OSH park.

Also, I'll eventually make an adaptation of the video board for the Genesis 2 (I'm also asking about the PIC 12C508/P here http://www.assemblergames.com/forum...ive-2-PAL-60Hz-color-fix-with-a-2-pin-crystal, I'll do some test anyway and use a 74HC04 if it doesn't work).

 

I've got my boards!


and I've started to solder some components:


It's a bit late here, I'll continue tomorrow, and this weekend I'll plug everything!