I mentioned the thought of adding a USB port to the Ti-84+ so that you can plug in a USB drive directly to the calc without having to use another cable.

As I was pondering about the soldering, I realized that if I soldered the hub to the mini USB port leads, there might be a shortout if one were to use both ports simultaneously.

How can I avoid this?
I don't think anything would short out, but neither connection would work until you unplugged the other one. The most "correct" way to do it would be to electrically disconnect one port when the other one was in use; if you chose which one would take priority, you would need only one of these circuits. In other words, if you plugged the calculator into a computer and a flash drive into the calculator, the calc-comp connection could trigger your circuit to disconnect the flash drive. In most cases, removing the +5V power from the port should be sufficient. Hopefully the extra capacitance on the D+/D- lines wouldn't ruin the communication on the other port, but I would rather you tested that to make sure.
So, if I were to solder as I described, I wouldn't ruin the calculator? Do I need to manually add a mechanical switch to the body to flick on one port or the other?
GinDiamond wrote:
So, if I were to solder as I described, I wouldn't ruin the calculator? Do I need to manually add a mechanical switch to the body to flick on one port or the other?
That would be the less-automatic but probably equally-effective solution. Assuming you didn't damage anything else in the calculator with your soldering, bridge components, or accidentally desolder some of the SMT components, I don't see much permanent damage that could occur. Of course, if you're not comfortable soldering tiny wires onto the USB port pins with the danger of permanent calculator damage if you slip, I would advise against it.
I guess I'll practice soldering first with something else...

I'm going to get that USB cable converter thing. I was thinking, "Hey, I have a MIDI keyboard! What would happen if I plug the keyboard into the wall, and then plug the keyboard to the calculator? Would it be possible to make a driver for the keyboard and make a synthesizer on the calc?"
Would electrical tape or solder be better for putting a USB A Mini male head on a USB A Female head?
GinDiamond wrote:
Would electrical tape or solder be better for putting a USB A Mini male head on a USB A Female head?


It depends; how long are you going to be using this setup? Tape works if you aren't going to be using it over a long period of time, but solder is much more permanent and will hold up better.
Can I be sure that China has the same wire color setup as America does?
GinDiamond wrote:
Would electrical tape or solder be better for putting a USB A Mini male head on a USB A Female head?
Both. You should solder the conductors, wrap them in a little electrical tape, and then heat-shrink-wrap the lot.
Yeah, but does China have the same color scheme that America does for the wires? They both have black, white, red and green wires, but do they go to the same pins?
GinDiamond wrote:
Yeah, but does China have the same color scheme that America does for the wires? They both have black, white, red and green wires, but do they go to the same pins?
It's not by country, it's by manufacturer. That's why benryves and I were telling you to use a multimeter or continuity tester to check which conductor goes to which pin.
Could I use a 9-volt battery to see which pin is which?
Oh! And...

what about a backlight? Could I add one?
  
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