I'm using this code to read the a value from a potentiometer and write it to an LCD character display. It is part of a larger sketch that I use to control my coil gun.
//Read in the value of the potentiometer and map it do the pulse time.
pulse_time = map(analogRead(timer_pin),0,1024,0,200);
//Output pulse time to LCD screen.
lcd.setCursor(7,1);
lcd.print(pulse_time);
However, the values displayed on the screen are irregular. When rotating the pot, the value increase rapidly from 0 - 900 withing the first half of the rotation. Then the values go back to 100 and start incrementing gradually until the pot hit's it's upper limit. What's wrong?
Ok.. I figured out what went wrong.
Basically, what was happening was that in the first part of the potentiometers scale, the numbers output to the LCD were two-digit ones. Then, after the mid point, the numbers become three digit. (i.e 99 --> 100).
When I turned the pot back down from 3 digit numbers to the two digit number range, the last 0 (of the 100) was not erased.
So instead of displaying 99, the screen would display 990 where the 0 was just left over from the last number displayed. Since all the numbers lower than 99 were also two-digits long, the 0 remained, making all the small numbers look like they were multiplied by 10.
I hope that made sense..
EDIT: Clearing the LCD or printing a row of spaces will introduce a lot of flicker into the display.
For the benefit of anyone else who might have the same problem, here's the solution.
Print a single character after each number. That way, any digits left over from the previous number are overwritten, leaving the display with the proper value.
