Keyboard freaks out by Wacom tablet

enmanneleu wrote:

Charles Minow wrote:
One more thing I didn't think of before: what kind of keyboard do you have?

An apple keyboard. The new thin one with wire.

I have now tried the tablet on another computer (PC) and it worked but the LED on it flickered. Maybe because it did not get power enough? But I don't understand how this affects the keyboard?

Because the tablet and keyboard are both USB devices, there are certain things they share in common. Both are electrical devices connected to the same bus on the computer. And there would be a certain amount of commonality between their data paths once the electrical signals reach the computer. When you push a key on your keyboard, it sends an electrical signal to the computer that Mac OS X interprets as a key press. The tablet also sends electrical information to the computer, it's just interpreted differently by the computer.

This is a vastly oversimplified explanation, but suppose the keyboard sends its signals to the computer and identifies itself as USB device 1 and the tablet identifies itself as USB device 2. But the actual content of the signals each sends is pretty much the same, just data that represents a series of numbers. It's really important, then, for OS X to be able to distinguish between them, because the signal from the keyboard for pressing the letter "a" might be the same as the signal from the tablet when you click at a pixel 20 in from the left and 67 in from the top, with a pressure of 50%.

So, how would OS X be confused between the keyboard and tablet? It could happen for an electrical reason. For example, only part of the data from the tablet or keyboard gets to the computer, but enough that OS X can at least try to interpret it. Or, once the data gets from the tablet or keyboard, the software that listens to the USB devices tells OS X the wrong thing about the information it received. Each USB device has an associated driver that interprets the signals from that device and tells OS X what to do. There could be a bug in a driver that would take the signal from Device 2 (the tablet) and assume it came from Device 1 (keyboard), and then send OS X the wrong information. But I think it's less likely to be a keyboard driver bug if you use the default Apple driver, which you'd use with one of their keyboards.

The LED on the tablet flickering makes it sound like a problem in the tablet itself or with its USB cable, and not a problem with the software on your Mac. If you know someone else with a tablet who could let you borrow theirs for a short time, that would also be helpful. If their tablet works, and doesn't interfere with the keyboard, then you know it's more likely to be the tablet itself and not your computer.

One other thing is to move the keyboard and tablet to different USB ports on your iMac. I think you have four to choose from, right? Perhaps there's something wrong with one of the ports on the computer, a bent pin or maybe a piece of dust that's causing a connection not to be made.

charlie

Hi--

Welcome to the Apple Discussions.

First, is your Wacom tablet connected to the USB ports on your Mac or did you plug it into the keyboard? There isn't enough power going to the keyboard to power a Wacom tablet. You need to plug it either straight into the back of your iMac or into a powered USB hub.

A second suggestion would be to see if you can find someone else with a computer who will let you test the tablet on their computer. It may be a problem with the tablet, like a frayed or shorted USB cable.

One last thing to check is to move anything that might be generating an electrical or magnetic field away from your Wacom tablet. I've seen very strong magnetic fields interfere with a Wacom tablet. Your iMac alone shouldn't do this, so look for another device you might recently have added to your desk.

charlie

enmanneleu wrote:
Okey, i will try it on another computer. If the USB cable is frayed or shorted - do you know if it can be repaired?

I don't know about the Intuos3 tablets. I have an Intuos2 and it looks like the USB cable is molded into the tablet itself. I have one of their Bamboo tablets, and the USB cable could probably be replaced in it. It comes out of the tablet, though it also looks like the connector is not a standard USB one on that side.

One more thing I didn't think of before: what kind of keyboard do you have? It might be possible if you had a non-Apple keyboard with special driver software, that could interfere with the tablet.

charlie

enmanneleu wrote:
OK. I understand... But actually it doesn't sound exactly like my situation, since the whole "keyboard layout" changes (I don't know the proper english phrase, because my OS is in swedish). If I choose "keyboard view" from the "language settings menu" when the tablet is connected, the whole layout is changed.

Your English is fine, "keyboard layout" makes sense. I see what you're saying: that's very interesting that the keyboard viewer shows the wrong characters on the keys. Can you figure out if there's a pattern to it? In other words, are the keys the same as you'd get on a Swedish key layout under different circumstances, like the "option" key is pressed or something like that?

Do the keys come up wrong in the same way every time? In other words, is the "a" key always the same wrong letter? That might mean something.

To your description of what could be wrong, it sounds more like a letter now and then should be wrong?

Not necessarily, if there's something causing interference or corrupted data, maybe it's adding the same information all the time. So maybe it adds 20 to the key code you pressed, so then

I've tested different USB ports for both the tablet and the keyboard and also tested to connect other USB devices to see if they affected the keyboard in the same way, but they didn't.

It definitely sounds more and more like a problem with the tablet itself (or its driver). You could maybe try different versions of the Wacom driver. I'm pretty sure that I've seen an "archive" of older drivers on their site. Just start working back from the newest one to see if an older one doesn't have the problem.

I will borrow a tablet from my work tomorrow and test it.

Another excellent idea. I didn't know if you had that option available to you....

charlie