Working code

.gitignore

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+build-uno

Makefile

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+ARDUINO_DIR=/usr/lib/arduino
+ARDMK_DIR=/home/j4nk/.local/Arduino-Makefile
+AVR_TOOLS_DIR=/
+
+MONITOR_PORT=/dev/ttyACM0
+
+include ${ARDMK_DIR}/Arduino.mk

main.cpp

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+/*
+  LiquidCrystal Library - Hello World
+
+ Demonstrates the use a 16x2 LCD display.  The LiquidCrystal
+ library works with all LCD displays that are compatible with the
+ Hitachi HD44780 driver. There are many of them out there, and you
+ can usually tell them by the 16-pin interface.
+
+ This sketch prints "Hello World!" to the LCD
+ and shows the time.
+
+  The circuit:
+ * LCD RS pin to digital pin 12
+ * LCD Enable pin to digital pin 11
+ * LCD D4 pin to digital pin 5
+ * LCD D5 pin to digital pin 4
+ * LCD D6 pin to digital pin 3
+ * LCD D7 pin to digital pin 2
+ * LCD R/W pin to ground
+ * LCD VSS pin to ground
+ * LCD VCC pin to 5V
+ * 10K resistor:
+ * ends to +5V and ground
+ * wiper to LCD VO pin (pin 3)
+
+ Library originally added 18 Apr 2008
+ by David A. Mellis
+ library modified 5 Jul 2009
+ by Limor Fried (http://www.ladyada.net)
+ example added 9 Jul 2009
+ by Tom Igoe
+ modified 22 Nov 2010
+ by Tom Igoe
+ modified 7 Nov 2016
+ by Arturo Guadalupi
+
+ This example code is in the public domain.
+
+ https://docs.arduino.cc/learn/electronics/lcd-displays
+
+*/
+
+// include the library code:
+#include <Arduino.h>
+#include <LiquidCrystal.h>
+//#include <Time.h>
+
+// initialize the library by associating any needed LCD interface pin
+// with the arduino pin number it is connected to
+const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
+LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
+
+void setup() {
+	Serial.begin(115200);
+	// set up the LCD's number of columns and rows:
+	lcd.begin(16, 2);
+	lcd.clear();
+	// Print a message to the LCD.
+	//lcd.print("hello, world!");
+}
+
+void loop() {
+	
+	// set the cursor to column 0, line 1
+	// (note: line 1 is the second row, since counting begins with 0):
+	lcd.setCursor(0, 0);
+	// print the number of seconds since reset:
+	//lcd.print(millis() / 1000);
+	while (Serial.available() == 0) {}
+	//lcd.clear();
+	String s = Serial.readString();
+	s.trim();
+	int nl_idx = s.indexOf("?", 0);
+	if (nl_idx == -1) {
+		lcd.print(s);
+	}
+	else {
+		String l1 = s.substring(0, nl_idx);
+		String l2 = s.substring(nl_idx+1, s.length());
+		lcd.print(l1);
+		lcd.setCursor(0, 1);
+		lcd.print(l2);
+		
+	}
+}