lcd cell count

Other Hardware Displays
1

Hi, this is simple but I am missing the plot. I have searched but can't find the info so hope somebody can help.
on a 16 x 2 lcd, I only want to autoscroll left if there is something in the last cell, otherwise noautoscroll. How do I detect if something is printed in the last cell of the lcd?

2

The screen doesn't give any feedback, so unless you keep track of what you display (using some kind of counter or quite simply an array), there is no way of knowing what is in each cell.

3

The screen doesn't give any feedback, so unless you keep track of what you display (using some kind of counter or quite simply an array), there is no way of knowing what is in each cell.

Actually the screen can give feedback but this functionality is not implemented in any of the LiquidCrystal libraries that I know of.

I have never tried this but the sequence should be essentially as follows:

  • Implement the R/W line (LCD pin 5) instead of connecting it to GND.
  • R/W low (write)
  • RS low (instruction)
  • Set the cursor to the desired address.
  • R/W high (read)
  • RS high (data)
  • E high then E low (get the data)

If you pulse E again you will get the data from the next address (I think). If you have previously set the address counter to decrement then you will get the data from the previous address.

Don