Author Topic: Can I use a SSC-32 wirelessly without a microcontroller? Possible solutions...  (Read 2589 times)

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Offline parallaxTopic starter

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I'm looking for a means to control at least 18 servos with minimal electronics on board the bot itself.

I was curious if there were any solutions for controlling a SSC-32 wirelessly with something like a xbee thereby bypassing the micro-controller altogether.

Here is a link to the SSC-32, it's data sheets and user guides.

http://www.lynxmotion.com/Product.aspx?productID=395&CategoryID=52

The reason why I ask is that it has some nice flexibility in regard to controlling large amounts of servos. You can use timed moves, coordinated group moves, and control the servo's speed. As far as I know there isn't much else out there like it (with the exception of the Phidget Advanced Servocontroller, but that only controls 8 servos and is USB only).

Alternatively I suppose I could go with an Axon and a bluetooth link, although I have no idea how to access bluetooth via C or C++ (which is what I am programming in) and I think I would lose some of that functionality I spoke about earlier...       

Anyone have any ideas/solutions?
"Less than a drop of blood in me remains that does not tremble;
I recognize the signals of the ancient flame"

Offline Soeren

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Hi,

Not that I have any experience with the 'bees, but if what comes out of them is just the serial signal put into them and there's no handshake, neither at the 'bee, nor at the SCC, then all you'd need should be a few components to deal with level translation (SCC claims "true RS-232 levels", which means they're bipolar) and I guess the 'bee is unipolar.
If, on the other hand, a handshake is expected...
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline parallaxTopic starter

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Soeren,

Thanks for your quick response! I hadn't thought about the initialization of the xbee communication whatsoever. There's got to be a handshake involved, which makes perfect sense when you stop to think about it. Otherwise if you had multiple bots in one room using xbees they would all respond at the the same time to the same transmission (I suppose there are times someone would want that, though). There would have to be a way for one xbee to differentiate itself from another. Am I right?  :)
"Less than a drop of blood in me remains that does not tremble;
I recognize the signals of the ancient flame"

Offline Soeren

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Hi,

I have no experience with those, unfortunately, so somebody else will have to tell you this, but it do sound logical.
I was referring to serial handshake on the "RS-232" port. If there's none there, I think you could pull it off.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline KurtEck

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The SSC-32 should work fine with this.  There are probably a couple ways to go. There are several threads on connecting the SSC-32 wirelessly up on the Lynxmotion forums.  There is even a tutorial on hooking one up with bluetooth.

1) I have seen a few members up on the Lynxmotion forums using a XBee with a new board that converts to RS-232, which you could probably use.

2) There are jumpers on the SSC-32 that connect the TTL level serial input/output to the DB9 connector through an RS232 conversion chip (like a Max232).  You can remove these jumpers and connect the inputs from either a micro controller or some other input to these jumper locations.  That is for example how we connect up the Lynxmotion Bot Board 2 (with a Basic Micro Atom Pro or Basic Stamp) to a SSC-32).  There are three pins up there, a TX, RX and ground. 

The SSC-32 is a 5v board and XBEES are 3.3v so you need some adapter board to do voltage conversion.  I have used both Selmaware as well as spark fun units (up on other thread).  Sparkfun are cheaper and smaller and on the robots that I have them connected to BB2s they work great on my Axon2 I was having problems.  I think there is an issue with the voltage conversion as there have been a few threads on this.  So on my Axon2 based Lynxmotion Brat I am using the selmaware one which has a conversion chip and it is working like a champ.

As for different robots in the same room, yes you can do it.  Note: I am currently using version 1 Xbees which are simpler to setup but I have maybe 4 robots with XBees on it, plus my XBee based remote control (thread up on Lynxmotion), plus an XBEE on my computer.  I am currently using transparent mode (will probably convert to API mode).  In transparent mode you enter command mode by outputting +++ without anything going to it before for a certain amount of time and likewise for a certain amount of time after.  Once in command mode you can change who you are talking to by issuing the ATDL command.  You can set each XBEE to different addresses (ATMY xxx). 

I hope that helps.

Kurt

Offline parallaxTopic starter

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Thank you very much! I assume this is the bluetooth tutorial you were referring to:

http://www.lynxmotion.com/images/html/build125.htm

You guys have been a big help. I really appreciate it. I'll post back here with what I ultimately end up doing (or doing wrong, in which case I'll be asking more questions about this  ;) ).





"Less than a drop of blood in me remains that does not tremble;
I recognize the signals of the ancient flame"

 


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