Hi all...

I've got a bunch of SX48/52 proto boards that I have used to build a custom brain for a combat robot I'm designing.  My programs work just fine, and I'm at the point where I need to actually make the little guy move, and I've hit a snag.  Is there anything special that I need to do to enable the servo connectors on these boards?  The schematics seem to show that they are already hardwired, but I don't get anything when I connect servos to the boards.

The schematics also mention a connection (actually, several connections) for Vsvo.  I seem to recall reading somewhere that one shouldn't use regulated power for servos and DC motors - do I need to connect an alternate power source for the servos?

I know that my servo logic is good because I tested the basic program (movement only) on a BS2px.  The boards just don't seem to be providing any power to the servo connectors.

Thanks...

Jamie,
As I recall, the power switch switch is a three position switch.  Position 0 = OFF, position 1 = Power to logic only, position 2 = power to logic and servos.

I use regulated power for servos all the time, but that's because I'm driving them from a big 100 VAC powered supply.  If you're running off batteries for your bot, then giving them raw battery power is probably better.  Just make sure the battery voltage doesn't exceed the allowed voltage for the servos.  
In addition, you can't really power them from the regulator on the proto board since it's a linear regulator limited to about 1 AMP - but only with a heatsink the size of Cleveland.  Run a bunch of servos and you;ll get a burning hot voltage regulator in no time.

Thanks Peter and Mike!

I knew that I had to have been missing something boneheaded...  :-)  
It never even occurred to me that a jumper was needed to select the voltage source - of course, that would explain why there's no continuity across those pins, wouldn't it?  ;-)  It's always the simple things - I practically have a neural network running on these SXs, and I get strung up by a missing voltage select jumper.  Gotta love it...

As far as the amperage for the servos, I was wondering about that...

Thanks again...

All--

I recently discovered the SX Controller Board which uses the SX28 chip. My question may be very simple and very obvious . . . to everyone but me!

I wonder why Parallax chose the 28 pin SX chip instead of the 48 pin SX chip with the extra I/O pins for the product?

It APPEARS that the SX chip is pretty much standalone except for power and the external ocillators needed. (I am nowhere near to being well-versed in electronics.) Is there a schematic describing such a cobbled-together device?

Thanks!

On the Professional Development Board, in the upper right corner, is a dual row connector ("X1") for an LCD panel.  Does anyone know of a source for a 6-9" cable that will connect from that to a STRAIGHT, SINGLE ROW connector of 14 pins (something similar to the picture attached below).

John,
How about this:

http://www.toby.co.uk/content/catalogue/products.asp?series=A04a-xx-BT1-G
I stumbled around for a bit trying to find this.  For what it is worth, my Google search terms were:

single row idc
I mention this in case the above link doesn't work out for you and you want to pick up where I left off.

Thank you Peter!

You are right though, I was looking for the whole thing already done (for the school).

Peter,
You did get me on the right track though!

On Prof Dev Board
14 pin IDC Socket, Dual Row
Mouser # 164-9007, $0.46 ea
On LCD
14 pin IDC Socket, Single Row
Mouser # 581-208284014000030, $3.34
Then ribbon cable between.  
I haven't seen these yet (order pending) but it looks like it will work.  Thank you again Peter.  Sometimes I just need the right search terms.

John,
I'm glad you took up the baton and found what you needed.  You're right about having correct the search terms, that's why I posted them.  I have a friend who isn't computer savvy at all, but he always seems to know the right terms for Craigslist to find what he's looking for.  When I saw your situation, those were the terms that popped into my head.  They seemed to offer some decent hits.  
Glad to see you found your parts "locally," rather than all the way in the U.K.  I also appreciate the details on the Mouser part numbers.  This is something that I just know I'll need one of these days.

Okay,
Here is what I need to do or find out if it is possible.

Lets say I have 20 standard I/O switches. With the propeller chip, can you detect those switches and program it to send ASCII keyboard codes to the PC via PS/2 or USB.

So pretty much I need to detect when a switch has been closed and in return send the ASCII command to computer. Like making your own keyboard. Also it would have to be able to realize when a key is continuously pressed.

I am at whits end and I know this has to be possible with some kind of PIC.