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Roborealm + Sabertooth 2x5 + DB9 - HOW?
Muhammad Haris Iqbal from Pakistan  [3 posts]
8 years
Hello Guys!
I just recieved my Sabaertooth 2x5 today, unfortunately i've not been able to get it connected to my laptop. I tried my Serial cable (DB9), which i use for communicating my Atmel 89S52 Microcontroller with Hyper Terminal, but gained no success.

I'll now try my Prolific USB to serial DB9 cable for interfacing..... I was wondering which pins shall i use to connect, can someone guide? And what baudrate shall I use?

Thankx!
Muhammad Haris Iqbal from Pakistan  [3 posts] 8 years
I figured after some research that RS232 needs to be converted to TTL so I got a simple RS232 to TTL Level converter Schematic from the internet and built it on to a PCB.

I then set everything up and still no succcess!
Sabertooth's LED went dim once or twice in some attempts but the motors did'nt still move a bit!

Someone please help.....dont have time, as my projects' deadlines approaching and am not able to do anything without sabertooth!

Help Please!
Anonymous 8 years
Have your reviewed this page?

http://www.dimensionengineering.com/appnotes/Roborealm/Roborealm.htm

STeven.
Muhammad Haris Iqbal from Pakistan  [3 posts] 8 years
Yep I did read it, actually I read it before even buying Sabertooth!

Today I got the problem solved, I was using raw RS-232 signals, I used MAX232 to convert the signals to TTL and now Sabertooth works fine.

I tried the Red object detection code, it works but not so efficiently my robot behaves in a wierd manner, It has alot of jerky movements and the traking is not smooth as it should be.

I am using RoboRealm with a Vmicro Webcam at 320x240 resolution all running on 1.6Ghz Pentium Mobile - Dell D800 Laptop.

are the specs of my hardware limiting the processing? Should i consider changing the laptop or the Webcam?

Thanks!
Anonymous 8 years
Muhammad,

There can be serveral reasons that your robot is jerky. Most likely the values generated by the VBScript module being sent to the Savertooth are too drastic a change. The red object example was made for a servo that would basically go from 0 to 255 within the width of the screen. I doubt that this translates exactly to a motor using the Sabertooth. What you need to do is relax the values being sent to the Sabertooth that are generated in the VBScript module. For example:

SetVariable "SERVO_VALUE", 128 + Cint((GetVariable("COG_X") * 16)/GetVariable("IMAGE_WIDTH")) - 32

would cause the motor values to range from 112 to 144 (32 values around the neutral 128) which should be much softer values to the motors. If they are too soft try using 32 or 64 values and see if that helps.

Also check your FPS? What rate are you running at? That's the number in the status bar in the main RR interface. If it is above 10 you should be ok. Below 5 will probably cause some oscillations  in your robot ... but not jerky movements.

STeven.

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