I currently have a self designed I/O board. I'm using the LPC1768FBD100 Microcontroller NXP 3V3 and created 20 inputs and 14 outputs. My design allows only inputs to be inputs and outputs to be outputs. Below you can see the input and output part.

So right now I have dedicated output pins and input pins What I would like to know is, What do I have to do electrically if I want to make a pin to be both Input and Output. Can I just connect the end of the input circuit to the I/O port and the beginning of the Output to the same I/O and add something extra electrical components to make that work, or do I have to change the complete circuit? Is there someone with an example or information about this?

LPC1768FBD100 datasheet.

Input circuit into microcontroller

Output circuit

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    \$\begingroup\$ I recommend that you turn off the grid before taking screengrabs. The text is hard work. Can you add links to the datasheets? Proper GND symbols would also help legibility. I can't see what's an input and what's an output. e.g., "24 V Outputs" has an arrow pointing into U28 which makes it look like an input. \$\endgroup\$ – Transistor Apr 16 at 15:12
  • \$\begingroup\$ This is why I never even tried gEDA. The developers seriously chose these colors as sensible defaults. Makes you wonder what other choices they've made. \$\endgroup\$ – pipe Apr 17 at 7:39
  • \$\begingroup\$ It's not possible to remove the grid or change the GND symbol to a normal ground symbol. I added the datasheet for the microcontroller and the U28 is a high-side switch (ITS4200S-SJ-D Smart High Side Switch SO8: nl.mouser.com/datasheet/2/196/…) after the high side switch is the connector P28 which is the output. \$\endgroup\$ – Dukel Apr 17 at 7:42

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