#30907 - Piratero - Mon Dec 06, 2004 12:32 am
I recently made my own xboo cable using an official nintendo gba link (cable is colored gray and purple). It works lovely but when i turn the gba sp off it has a flickering dim red light, if i turn it back on it turns completely red. if i disconnect the cable while the gba is off the dim red light goes away. i was told this is very bad. any opinions?
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#30931 - Krakken - Mon Dec 06, 2004 8:25 am
I get that too. Not at all sure why... it just happens. Oh well.
#30962 - ampz - Mon Dec 06, 2004 6:08 pm
Sounds like the xboo cable is forcing current through the ESD protection diode to GBA VCC. Not exactly a healthy thing for electronics, no. (can burn out the ESD protection diode, which makes the GBA rather sensitive to ESD damages) Don't leave it like that for extended periods of time.
You will be just fine as long as the GBA is powered up while it is connected to the xboo cable.
If you want to get rid of the problem, then one solution might be to add current limitation resistors in series with the signal lines.
#31019 - Piratero - Tue Dec 07, 2004 1:40 am
| Quote: |
| then one solution might be to add current limitation resistors in series with the signal lines. |
signal lines? you mean certain pins on the db25 connector? is there different kinds of resistors or is there just one i should get?
thank you ampz for your input
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#31056 - ampz - Tue Dec 07, 2004 12:37 pm
Higher value resistors will provide more current limitation, but could limit the possible xboo performance.
1kohm is a conservative value.
Don't go below 100ohm.
But as I said, you will probably be fine without resistors as long as you don't leave the GBA connected while powered off for any periods of time.
#34407 - ZeroX - Wed Jan 19, 2005 2:29 am
Isn't it because the parralel port outputs 5V when HIGH, opposed to 3.3V by the gba link port? Zener diodes would be better, right?
#34646 - ZeroX - Sun Jan 23, 2005 6:21 am
Piratero : Putting current limiting resistors wont really help u and will cause your xboo cable to stop working, if u use wrong values for your resistors. Even the range quoted by Ampz wont help u, as i have tried this a while back. It caused my cable to stop working, enough said. (If u wanna know i used 1.2k, then 1k, then 600 ohm, then 500 ohm, then got pissed and pulled out my hair, cause when i take them out the cable works)
The best solution (if doesnt work,well that's too bad) would be to change the parellel port settings in your bios from "ECP+EPP" or "EPP" or "ECP" to "Normal" or "SPP". "Normal" should be okay, well, at least my other devices work fine in this mode. And these setting vary on different motherboards. For example my motherboard does not have the "SPP" setting, my brother's one does. This should be able to help u.
Word of warning: If ur gba sp has a flickering GREEN light after u off it, STAY AWAY from that PC! This means that a much higher current is being forced through the protection diode to the GBA Vcc, and can burn it out. It seems to happen in my old AMD-K2 motherboard. Probably cause the motherboard is a crappy one, or a screwed up power supply, since it gives out +5.9V instead of just +5V. :/
Hope this helps :)
#34721 - Piratero - Tue Jan 25, 2005 1:34 am
| Quote: |
| It caused my cable to stop working, enough said. (If u wanna know i used 1.2k, then 1k, then 600 ohm, then 500 ohm, then got pissed and pulled out my hair, cause when i take them out the cable works) |
well, where did you solder the resistor to?
edit:
for me it's not a flickering green light, it's a very very dim red flickering light
thanks for the info ZeroX
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#36397 - irondonkey - Fri Feb 18, 2005 10:25 pm
I'm not extremely experienced with electronics yet, but it seems to me that a couple operational amplifers should be able to reduce the 5 volts from the computer to 3.3 volts for the gameboy. I'll see what I can figure out, in the meantime, if somebody actually knows more about this kind of stuff, feel free to set me straight.
(edit) Missed the post about the zener diodes... that'd work too, if anybody is interested, I'll post a schematic
#36420 - ampz - Sat Feb 19, 2005 11:25 am
Operational amplifiers are not the way you usually translate digital signals from 5 to 3.3Volts.
In the case of the xboo, a few series resistors are sufficient.
#36467 - Piratero - Mon Feb 21, 2005 10:20 pm
which pins should i add the resistors to? i think they should be on pins 5 to 9?
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#36478 - arakawa - Tue Feb 22, 2005 1:43 am
There should be voltage regulators for this range. They are much better than zenner diodes or resistive dividers and much simpler than op-amps. Although I have no idea wtf an xboo cable is.... :P
#36498 - Piratero - Tue Feb 22, 2005 11:54 pm
an xboo cable is a cheap way of uploading your rom onto the gba without a cartridge. it's done by copying the whole < 256K ROM to EWRAM.
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#36546 - arakawa - Thu Feb 24, 2005 1:49 am
OK, so a voltage regulator does exist:
"Both regulators are ideal for converting a common 5V logic supply, or higher input supply voltage, to the lower 2.5V and 3.3V supplies to power VLSI ASIC's and microcontrollers"
http://www.national.com/pf/LM/LM2937-3.3.html
#47301 - solarwind__ - Thu Jul 07, 2005 4:03 am
yeah, just use voltage regulators to regulate the voltage to 3.3 volts. you might have to buy a few of them in a computer parts store. or you could try pulling coil out of an old moter and adding it to your wire, (a stupid and cheap way but it might work, dont blame me if it doesnt)
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