Those pesky mice...

[Altainia]

This year knowing where you are would be muy importante. Thus, our team has kind of decided to use optical mice, two of them, to determine position and direction. After doing some searching I have cleared up some of my questions but I still have two:

1) Does anyone have a brand they might recommend and a way to (semi) easily wire both mice to the Robot Controller? (e.g. a converter)

2) If not, with a recommended brand could you include specs on the wires so I could (hopefully) do it myself?

Thanks.

[EricH]

Originally Posted by Altainia

This year knowing where you are would be muy importante. Thus, our team has kind of decided to use optical mice, two of them, to determine position and direction. After doing some searching I have cleared up some of my questions but I still have two:

1) Does anyone have a brand they might recommend and a way to (semi) easily wire both mice to the Robot Controller? (e.g. a converter)

2) If not, with a recommended brand could you include specs on the wires so I could (hopefully) do it myself?

Thanks.

The Chiklet is the only legal way to do a USB conversion to the controller ports. It does need its own power, though.

Barring that, you would need to wire your own connection.

[DonRotolo]

I think he means to mount the mice on the robot; in such a case the chiklet/etc restrictions would not apply.

I can't help with the mouse interface though. But, do keep in mind that it is essentially dead reckoning, so errors are cumulative and significant (meaning important).

Don

[Altainia]

Originally Posted by Don Rotolo

I think he means to mount the mice on the robot; in such a case the chiklet/etc restrictions would not apply.

Yes, that is what I mean. I realize we cannot use the chicklet, though. However, by searching these forums I get the distinct impression teams from past years have managed to do what we plan to do. Looking at diagrams is helping me some but to anyone with experience doing this... Please help!

[Doug Leppard]

Using mice is what robot enthusiasts have tried in the SRS robotic groups. I have heard of one person doing that with small robots. My concern for these fast moving robots is that you would go faster than the mice could record and keep up with.

[Altainia]

Originally Posted by Doug Leppard

My concern for these fast moving robots is that you would go faster than the mice could record and keep up with.

That's where the whole "we kind of decided it" comes into play... Really it was me and an engineering mentor. Our head and secondary engineers are currently gone on a scout camp out, so I haven't talked to them about our maximum speed. But really, I've got to start pursuing this now because if it does work it'll be great and if it doesn't I've got to learn how to use the quad optical encoders and gyroscope in unison...

Speaking of which, I've found a diagram I can use to wire a USB optical mouse myself. Unfortunately, I need to know what D+ and D- correspond to. I'm guessing one means data in and the other data out, but which way? (As in does D+ mean data going into the mouse or into the microcontroller?) Here's the diagram, courtesy of Wikipedia.

[DonRotolo]

No, USB uses two wires for data, so they are both carrying the same signals exactly, except one is inverted from the other. Google "Differential Signaling"

[Altainia]

...
Ah.
Because I so would've got that if left to my own devices, because of course that makes sense that D+ and D- would mean Differential Signaling.
...
That's why I stick to computers. And because I would've never been able to find that out on my own, Arigato, Don Rotolo.

Next question...

Is there any way to do the whole Differential Signaling before going to the RC? Because if I do my math correctly, 3 pins do not equal 4 wires.

[Binome]

Your definitly up for a challenge, if you want to use a USB mouse as a position sensor.

You are going to most definitly need an external co-processor, with a USB host chip, and appropriate firmware to decode the HID stream from the mouse to something the RC can understand, like a simple TTL serial stream.

If you can get a hold of some ps/2 mice, it can make your job MUCH easier, and you can easily decode ps/2.

Good luck!

[DonRotolo]

I agree: USB is not as simple as connecting it to the robot controller and decoding data. There is a LOT more in there...

I suggest some web searches, see if anyone else has done it.

Don

[Gdeaver]

Some mice use an Avago optical mouse controller chip and a Cypress microcontroler. On these mice you can by pass the micro controller and interface with the chip by SPI. That part will work. The problem is with the optics. Others have tried with custom optics. I don't think any one had success with FRC scale and carpet.

[jgannon]

Originally Posted by Altainia

I realize we cannot use the chicklet, though.

Why not? It's legal, and it will do all the trouble of decoding the USB protocol into analog voltages for the two axes. Then all you need is an adapter to go from gameport to three-pin headers, which is pretty much a ten-minute strip-and-solder job. You may have to buy the specific mouse that the Chicklet supports, but that is by far the easiest way to approach the interface problem... much better than trying to bit-bang.

[EricH]

Originally Posted by jgannon

Why not? It's legal, and it will do all the trouble of decoding the USB protocol into analog voltages for the two axes. Then all you need is an adapter to go from gameport to three-pin headers, which is pretty much a ten-minute strip-and-solder job. You may have to buy the specific mouse that the Chicklet supports, but that is by far the easiest way to approach the interface problem... much better than trying to bit-bang.

They're trying to use the mice as position sensors on the robot, not as driving tools on the OI.

[jgannon]

Originally Posted by EricH

They're trying to use the mice as position sensors on the robot, not as driving tools on the OI.

I know that. That's why I'm describing the process of adapting the Chicklet to mate with the three-pin headers on the RC.

[EricH]

Originally Posted by jgannon

I know that. That's why I'm describing the process of adapting the Chicklet to mate with the three-pin headers on the RC.

Ah, OK. The fun begins...Now, how do you power the Chicklet on the robot? Direct connection to the 7.2V battery, or will a three-pin header tranmit enough power?