Creating and Writing to Editable Fields on 4x20 HCD44780-Based Character LCD

[Amoque]

[B]What I need to do now is learn how to, using the on-board keypad, enter and edit editable fields on the LCD, then save the values to variables to be used in the program. Is there a document somewhere that covers this? Thank you for any and all input!

As I understand it, the LCD is a display only device - you will not be able to edit anything on screen; rather, you must edit the underlying variables and display the changed values. What I mean is that if you are displaying variable "A" at position 1, changing the value of "A" and rewriting it to the LCD will be the "edit". You might then change only limited values - say as in setting a clock (which BTW there are plenty of examples of on the forums that should give you ideas how this may be done) or, perhaps, you might want to define an array as an area of video memory and reprint that as the values change.

If you wish to incorporate some "rollback" feature (not finalize the change until approved, perhaps) you will copy the original value of "A" to say... "B", then display "B" until the final step where you write A=B to finalize - or B=A to rollback.

Generally, I find numeric fields easier (less tedious) to "edit" as addition or subtraction may be used to scroll through a range of numbers, but alphanumeric isn't too bad - I designate an area in EEPROM and manipulate READ values to increment or decrement values rather than deal with alphas directly.

HTH-

[mark_s]

This article has some really good info on keypad entry. He shows how to count key presses
and convert individual entries to a usable variables. Ignore the circuit since you are directly
connecting your keypad.

http://www.rambal.com/descargas/libr...%20Display.pdf