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

Hello Ryan,

The USB SX-Key is powered from the USB port so it shouldn't be causing any power issues.  On a side note, the orginal SX-Key (Serial based) required that your target system supplied 5V to power the SX-Key.  Since you are using the USB version I doubt the SX-Key is causing any power related problems.

It's cool that you were able to add the LED which confirms that the SX28 is indeed up and running.  Now it is a matter of troubleshooting the connection to the polou servo controller.  There are some other questions I have about your setup.

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

- 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.

- 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?

- 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.

Robert

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