Monthly Archives: December 2014

Adding USB to the “Fluidmotion” STEPPIR control box.

If you read some of my other posts you’ll understand that I have no love for the ancient RS-232 protocol , and have found that most items that use a 9 pin RS-232 port can be converted to USB.   Most logic level circuits have signals that use +5 volts for a logic “1” and zero volts as a logic “0”. RS-232 takes these 1’s and 0’s and level shifts them to a much higher voltage level – that has both positive and negative potentials – something in the neighborhood of plus and minus 10 – 12 volts. I guess the reasoning behind doing this is to insure that  determinable voltage levels survived long cable runs. In most Ham applications, the cable length is just a few feet – so signal level shifting of this type is completely unnecessary. USB
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