Using the miniSSC II

I am using the mini SSC II with matlab and am trying to control normal servos. I am using it is MINISSC II mode with the jumper and in the code I am setting the serial port to 2400 baud and 8N1 for transmission data. I send this:

fwrite(SSC,11111111)
fwrite(SSC,00001000)
fwrite(SSC,00000100)

Where SSC is the serial port name for COM5 the port I am using the controller on. and fwrite is a standard matlab function where fwrite(obj, A) in the function A is binary data to be sent. I send the data and it says it gets it fine, no transmission error, but just about every time the yellow light comes back on and I cannot figure out why. The other problem is that the servo doesnt go to the right position. I have used this controller successfully with my AVR microcontroller before and have had no problems. Any insight would be helpful.

Thanks,
John

Ok, well I got it working from matlab but for some reason it only wants to work when I power the control electronics from my STK500 development board and the servos seperately. I am indeed jumping the grounds. for example right now I have a brand new 9 vold battery hookedup to the servo power and then fromt he servo power to control power. When I go into MATLAB and send the commands, the green light flashes, (accepting the commands) then the yellow light goes back on. sometimes the yellow light doesn’t go back. When the yellow light doesn’t go back on the servo position isn’t what it is supposed to be, i will say for it to go to 0 and the servo will stay at 127 (the default value). What is happening?

I’m a little confused by your description, but it sounds like you found your own power problem. When the servos start to move, they draw a lot of current, and the voltage from your battery will start to drop (also, isn’t 9V way too high for hobby servos?). If the voltage drops too low, the servo controller will stop functioning, and stop sending a position command to the servo. The servo will then stop wherever it is (probably very close to where it started) and the voltage will rise back high enough to run the servo controller. Depending on how low it got, the controller will either be reset (the yellow light coming back on) or in some floating, non-functional state.

Is it a problem for you to power your motors and electronics separately? Also, what kind of 9V battery are you using? Are you actually connecting 9V directly to your servos?

-Adam