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I think the problem is that the circuit and code you copied emulates a Lanc controller, and you want to emulate a video camera. So the code needs to wait for a command from the controller, and send a suitable response.
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The interface circuitry is more complicated than necessary. All that is needed is one I/O pin with the 4K7 pullup to +5V and a 100 ohm series resistor to Lanc signal. The open-collector output can be emulated by switching the pin mode (or data direction register) to Output to send a Low, and Input to send a High.