lastfuture
Offline
Freiburg, Germany

Heya,

my LEDx3 backlight in my turned off DMG is glowing when I plug in the Link cable that's attached to the nanoloop USB MIDI adapter. It's about 3/4 the brightness that it gets when I turn the DMG on. It happens with and without inserted batteries. Looks like (some of?) the voltage of the USB port gets passed on by the adapter and passed on to certain parts inside the Game Boy...

Is this expected and more importantly is this safe? I don't want to damage anything.

I mean if it's safe this is great, it's kind of cool smile but I'd rather know sooner than when it's too late if I should only plug this in when the DMG is on and plug it out before turning the DMG off.

Saskrotch
Offline
Chicago IL

i got yelled at by kitsch for doing this with a ems 64mb usb cart

it's not good for your cart. there's also no reason to do it. take the cart out when you plug the usb in.

Apeshit
Offline
Saskrotch wrote:

take the cart out when you plug the usb in.

This is a completely different issue.

At any rate, this probably shouldn't happen. I'm rather unfamiliar with the device, but as far as I know it's a PCB that plugs into a link cable, for MIDI syncing? There should be no voltage pin present. Is it a genuine link cable?

threesecondsecret
Offline
London

I found this as well. Also, if you accidentally play the MIDI with the DMG off it changes brightness along to the notes wink

kitsch
Offline
matt's mind
Saskrotch wrote:

i got yelled at by kitsch for doing this with a ems 64mb usb cart.

i 'yelled' at someone today about this too wink

but, totally different issue...

lastfuture
Offline
Freiburg, Germany
Apeshit wrote:

I'm rather unfamiliar with the device, but as far as I know it's a PCB that plugs into a link cable, for MIDI syncing? There should be no voltage pin present. Is it a genuine link cable?

Yes it is a PCB with 4 USB pads on one side and 4 pads on the link-cable side (two on top and two on the bottom) that match up with all 4 pins in my genuine Nintendo Game Link cable for the DMG.

lastfuture
Offline
Freiburg, Germany

I'll grab my multimeter and measure where and how much current flows on the link cable side of the adapter. I'll be reporting back in a bit

Saskrotch
Offline
Chicago IL
kitsch wrote:
Saskrotch wrote:

i got yelled at by kitsch for doing this with a ems 64mb usb cart.

i 'yelled' at someone today about this too wink

but, totally different issue...

you made me cry in front of my family


still though, a backlight drawing power through a cart has got to do some kind of damage to the cart, right?

lastfuture
Offline
Freiburg, Germany
Saskrotch wrote:

still though, a backlight drawing power through a cart has got to do some kind of damage to the cart, right?

This is not through a cart, this is through the link port

lastfuture
Offline
Freiburg, Germany

My multimeter is dead hmm I'm afraid I can't measure right now

lastfuture
Offline
Freiburg, Germany

OK I was able to revive the multimeter by connecting it to a power supply.

And WHOA... here's my measurement: between the gnd and TWO of the pins there seems to be a pretty solid 5V when the adapter is connected to USB. In my picture I've labeled those pins 3, 5 and 6. 6 is gnd, 5 is clock and I think 3 is serial out

I'm not sure, but I can imagine it has something to do with the way signalling works, high being 5V ... how does this compare to say an Arduinoboy in MIDI mode (used for mgb)?

Last edited by lastfuture (Dec 2, 2012 10:15 pm)

lastfuture
Offline
Freiburg, Germany

OK I've been talking to nitro and can shed some insight.

Both the signals for clock and serial are normally high, that means 5V. So nothing is wrong with the USB adapter, it behaves just like an arduinoboy and just as expected. Now comes the fun part: According to this diagram http://gbdev.gg8.se/wiki/images/0/03/Ga … uboard.gif the two lines (ELP3 and ELP5) go to VCC on the main PCB, meaning everything that draws power from the regulated power source will get some amount of those 5V that come in through those pins. It may not be 5V but enough to make the backlight turn on if it was soldered to the regulated power source like kitsch's instructions suggest for example.

I take that this means the DMG is fine and nothing will be broken by this. Nice.

Not sure how healthy this is for the adapter though.

Last edited by lastfuture (Dec 2, 2012 11:05 pm)

fluxer
Offline

Does this mean your batteries won't drain as much when you've got this baby plugged in?

oliver
Offline

From the specs of the adaptor's controller:

Maximum output current sunk by any I/O pin.................................................................................................... 25 mA

lastfuture
Offline
Freiburg, Germany
fluxer wrote:

Does this mean your batteries won't drain as much when you've got this baby plugged in?

unfortunately not, according to nitro. The diode will only let current through if the voltage on the link cable side is higher than on the other side, which won't be the case if the DMG is switched on. That is to prevent voltage spikes from harming the chip