How to connect the battery in zelda 1 cart???

MaarioS · Post by **MaarioS** » Wed Nov 04, 2009 5:23 am

Hi guys!!!

I have problem with connecting the battery on my zelda 1 homebrew cart from a pirate famicom cart......

I connected the battery by this scheme:

and I added an extra resistor 10K with 1% or 4% tolerance between WRAM /CE2 pin and Ground. My friends tells me, this is the best way to connect this battery in this game. OK, but, if I'm playing this game for about 1 minute, then if I shut down the famiclone with reset or not, the data from the WRAM will be erased partly or all!!! In my second famiclone effects are similar..... But on my third famiclone if I shut down the console with RESET, all data will never been erased. I tried to remove the capasitors, add another, add another resistor, add something else but effects are similar with loosing the data.....

So, have you got any ideas how to connect the battery that should work on all consoles??? I think, the problem is not on the famiclones, because I'm playing an original Mouryou Senki Madara on every one and data in this cart have never been erased (with shutting down the console with RESET).

Bregalad · Post by **Bregalad** » Wed Nov 04, 2009 6:15 am

Shouldn't a resistor be there before DZ1 ?

MaarioS · Post by **MaarioS** » Wed Nov 04, 2009 6:53 am

If I add a resistor 10K, 1K with 5% tolerance, 1% tolerance whatever, before or after DZ1, effects are MUCH WORSE than before..... Effects are much worse, if I add any resistor from battery..... But this is weird, because if I connect a battery with this scheme and add a 10K resistor before DZ1 in kirby (but this is a MMC3 cart, but with battery backup), the game runs perfect and if I turn OFF any console with RESET or without RESET, all of the data are still in WRAM.....

kyuusaku · Post by **kyuusaku** » Wed Nov 04, 2009 8:45 am

Remove your 10K, wherever it is, and add a 1K resistor after D1. As long as the resistor provides sufficient current for data retention, the value isn't critical because it's only used to give preference to console current.

3V-.7V / 10K = 230uA = too low, even for a 6264LP (low power) in complete standby.

You decoupling capacitor on +5V is also somewhat redundant.

MaarioS · Post by **MaarioS** » Wed Nov 04, 2009 9:10 am

Well, OK. So, i removed this 10K resistor, and, I must add a 1K resistor between PRG D1 and GND??? So, I added this resistor and game freezes after pressing START......

EDIT: Oh sorry, I didn't read that correctly, you say AFTER

. But, I connected this 1K resistor between D2 and GND, and game after START freezes too...... After that, I connected this resistor between D0 and GND, and after pressing START the screen becomes pink and game freezes too....

kyuusaku · Post by **kyuusaku** » Wed Nov 04, 2009 9:35 am

?????????? D1 as in diode #1 in your diagram, not the data bus. This is what your circuit should look like:

Don't do anything with CE2, it should be controlled by the MMC1, a battery backup circuit or tied enabled (as should /CE).

MaarioS · Post by **MaarioS** » Wed Nov 04, 2009 10:21 am

kyuusaku wrote:?????????? D1 as in diode #1 in your diagram, not the data bus. This is what your circuit should look like:

Don't do anything with CE2, it should be controlled by the MMC1, a battery backup circuit or tied enabled (as should /CE).

Oh OK, i thought about D1 from PRG

. And, I connected this 1K resistor and effects are worse than before. After turning console OFF, I loose my data partly or all.....

kyuusaku · Post by **kyuusaku** » Wed Nov 04, 2009 11:10 am

I think you need to start over, there is nothing wrong with the circuit. Before that though, why don't you show us how you are connecting things now? It's not clear what kind of board you're using and what changes you've made.

MaarioS · Post by **MaarioS** » Wed Nov 04, 2009 1:05 pm

kyuusaku wrote:I think you need to start over, there is nothing wrong with the circuit. Before that though, why don't you show us how you are connecting things now? It's not clear what kind of board you're using and what changes you've made.

So, I used the pirate famicom cartridge and that was game Platoon (it is MMC1). Cart has got PRG and CHR only. I changed CHR ROM to CHR RAM and added WRAM by myself.

Here are some photos:

* i removed those resistors

label by myself

.

And I have got the problem with connecting the battery, because i often loose the data from WRAM (please read my first message in this topic). Before desoldering the chips, PCB hasn't got any resistors, diodes or capasitors.

.....Or my 1K resistor is broken, because I desoldered it from PCB of old not working radio. I will buy a new 1K resistors soon.

kyuusaku · Post by **kyuusaku** » Wed Nov 04, 2009 1:38 pm

How are you decoding WRAM?

MaarioS · Post by **MaarioS** » Wed Nov 04, 2009 1:54 pm

I connected adress and data pins to PRG pins (except A13 and A14 of course), pin #01 I connected directly to +5V, pin #20 to MMC1 pin #11, pin #22 to GND, pin #26 to MMC1 pin #06, pin #27 to MMC1 pin #17 and pin #28 I connected by this scheme.

MaarioS · Post by **MaarioS** » Thu Nov 05, 2009 4:25 am

Eeeemmm, wait a minute......

You just said, I must connect a 1uF capasitor between SRAM VCC and GND??? So, I connected a capasitor 104 between them, but this has got 100nF, so, I must bought 105 ceramic capasitors???

kyuusaku · Post by **kyuusaku** » Thu Nov 05, 2009 7:59 am

.1uF = 100nF.

..How are you decoding /OE and /WE?

And you're not supposed to connect /CE to MMC1.11 (PPU A16!)

-connect SRAM /CE to GND
-connect SRAM /OE to GND
-connect SRAM /WE to CPU R/W
-connect SRAM CE2 to MMC1 pin 6

MaarioS · Post by **MaarioS** » Thu Nov 05, 2009 9:01 am

SRAM /CE to GND??? But, I just followed by this scheme:
http://nintendoallstars.w.interia.pl/romlab/nesram.htm
but, OK, I connected this pin to GND and game runs and I can play it, but, the data is still erasing......

I just said, my zelda don't like resistors connected to battery, because I tested it..... This zelda is really painful....... I don't know whats going on......

kyuusaku · Post by **kyuusaku** » Thu Nov 05, 2009 9:15 am

MaarioS wrote:SRAM /CE to GND??? But, I just followed by this scheme:
http://nintendoallstars.w.interia.pl/romlab/nesram.htm
but, OK, I connected this pin to GND and game runs and I can play it, but, the data is still erasing.....

The pinout is wrong... Wire everything how I listed. There should only be one resistor and it shouldn't negatively affect the game in any way!