In SX Microcontrollers, SX/B Compiler and SX-Key Tool, uptonryan wrote:

Hi roboert, the servo motor works stand alone now after I connected the pololu ground and sx ground together.

>How are you powering the polou servo controller? Is it powered from your SX-board so they share the same logic supply?

Originally the pololu and sxtech board ground seperately with 7.5V 1amp for the sx and lab power supply for pololu. I then connected the ground of both those boards (but the Vdd is still seperate) and now it all works.

So there are three power supplies, one for pololu one for sx and one for servos.

>- Are the SERVO's connected to the logic supply or do they have their own power source? Servo's can draw quite a bit of power and need an adequate power source with good filtering or it may interfere with the operation of the CPU.

Servos have a seperate power supply

- How is the connection done between the SX28 and the servo controller? Is it a direct logic level connection or is there anything inline? You mention adding a cap to the serial line but I don't see where you would need that. How about pull-up/pulldown resistors?

I just ran hookup wire from pin 3 of the SX28 to logic in of the pololu controller. At one stage I had pull up resistors and an led to check coms.

- In regards to the servo controller does that have a fixed baud rate or does it 'auto-detect' the incoming data? If it auto-detects perhaps it is making a mistake.

I thought this as well. The pololu has an auto-detect. But it is confusing,It may fix it permanently once it detects it, but this is something that is not clear from the pololu manual or from experimentation. At the moment it seams fixed on 57,600 baud for one mode and 9600 for another mode.

Eventually I want all this to run from the same power supply. I have brought some capacitors to act as reseviours to do this.

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