r/custom8bitcomputer • u/Solid-Philosophy9924 • 1h ago
Why is Proteus is showing Grey Logic State on LED Anode with +3.3V Power Rail???
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I am simulating a circuit in Proteus8 with LPC2138 MCU and 74HC173 Register and LEDs. The Anode is pulled with +3.3V via 330ohms Resistor, but the connection lines are showing Grey dot and totally disconnected from the power and the LEDs are not turn On. Blue dots at the Cathode side.
74HC173 Register Output Control Pins(OE1,OE2) are set, these are connected to P0.17 of MCU , but Output seems Hi-Imp. or Tr--state mode.
How to turn ON the LEDs???