Minimig Shared RS232

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By wiring the MCU (PIC18) and the fpga via an AND gate one can eliminate the jumper currently present on the rs232 TxD.

RS-232:
Default voltage level is negative (-3 .. -25) = Logical "1"

AND Truth table:

Input0 Input1 Output
0 0 0
0 1 0
1 0 0
1 1 1

http://en.wikipedia.org/wiki/Rs232#Voltage_levels
http://www.winpicprog.co.uk/pic_tutorial7.htm

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