"read_volts = analogRead (A7);" will return an int, not a float. 0 to 1023.
float volts_value;
volts_value = read_volts * 5/1023; // no mapping needed.
"read_volts = analogRead (A7);" will return an int, not a float. 0 to 1023.
float volts_value;
volts_value = read_volts * 5/1023; // no mapping needed.