I have the robot TFT screen and i am using it for a small project.
I have a voltage sensor connected to analog pin A0 detects voltage 0-5v. The voltage measured is from a resistor voltage divider that lowers DC voltage from a battery down from 15v(max)-5v(max) for the arduino.
I am struggling on how to convert the measured value 0-5 back up the 0-15v value with a 1 decimal place accuracy and display it on the TFT screen.
i want to extrapolate the measured value back to a voltage (i.e 12.8v). I count 12.8v as 5 chars:  - 1  - 2  - .  - 8  - v
so i want to get the measured value (A0) convert to voltage in 0-15vdc range with 1 decimal place accuracy and append a 'v' on the end. Place all this in a 5 char array and print it on the screen.
i tried using the map function in psuedo code as follows:
// char array to print to the screen char volSen; int voltageSensor = 0; //read the voltage from the sensor connected to A0 voltageSensor = analogRead(A0); String batteryVoltage = map(voltageSensor, 0,1023,0,15); //send voltage to array batteryVoltage.toCharArry(volSen, 5); //HOW DO I APPEND A 'v' AT THE END OF THE ARRAY?? //Print the voltage on the TFT screen TFTscreen.text(volSen,0,0);