Kenwood AT-300 ATU to ICOM Radio - II

In a previous post I wrote about a devil plan to connect a Kenwood AT-300 Automatic antenna tuner to an ICOM 7300 radio.

Here is the connection diagram (again, by hand) and the final iteration of the code.

	// This is a simple sketch to controll a Kenwood AT-300
	// from an ICOM radio.
	// Compatible with: IC-7000, IC-7100, IC-7200, IC-7300, IC-706, IC-703
	/* See the schematic on http://yo3hjv.blogspot.com/2017/03/kenwood-at-300-atu-to-icom-radio-ii.html
	*/
	// This program is beer-ware (buy me a beer when you see me) and i will //appreciate
	// March 2017, Adrian YO3HJV, rev 7.0
	///////////////////////////////////////////////////////////////////////////////////
	// Define input and output
	// ICOM RADIO
	int KEY = 10;
	int START = 2; // for ISR
	// KENWOOD AT 300 TUNER
	int TS = 11;
	int TT = 12;
	// LED indicators for debugging
	int GREEN = 6;
	int YELL = 4;
	// SOME VARIABLES for future development
	int Istart = 0; // check if TUNE is issued by the ICOM radio. StandBy at 5V, goes LOW
	int Ktt = 0; // check if Tuner Start is issued by the Kenwood ATU. StandBy at 5V, goes LOW
	unsigned long duration;
	///////////////////////////////////////
	void setup()
	{
	// SETUP WHICH ARE OUTPUTS AND WHICH ARE INPUTS
	//LEDs
	pinMode(GREEN, OUTPUT);
	digitalWrite (GREEN, HIGH);
	pinMode(YELL, OUTPUT);
	digitalWrite (YELL, HIGH);
	//ICOM
	pinMode(START, INPUT_PULLUP);
	pinMode(KEY, OUTPUT);
	digitalWrite (KEY, HIGH);
	//KENWOOD
	pinMode(TT, INPUT_PULLUP);
	pinMode(TS, OUTPUT);
	digitalWrite (TS, HIGH);
	}
	void loop(){
	if (digitalRead(START) == LOW) {
	Tune(); // Execute external function TUNE
	delay (500);
	StandBy (); // Execute external function StandBy
	}
	}
	void Tune () {
	do {
	digitalWrite (YELL, LOW); // Light LED
	digitalWrite (TS, LOW); // init ATU
	delay(150); // wait for ATU uC to reset
	digitalWrite (KEY, LOW); // start Tx RF
	delay(300); // keep Tx RF for at least 300 msec
	}
	while (digitalRead(TT) == LOW) ; // TUNE untill TT is HIGH again
	}
	void StandBy () {
	digitalWrite(KEY, HIGH);
	digitalWrite (TS, HIGH);
	digitalWrite (YELL, HIGH); // Shut down LED
	delay(500);
	}

view raw Kenwood AT300 to ICOM radio hosted with ❤ by GitHub

Later edit:

This is the final look after some work on a test PCB. I let the USB port accesible for future development: