LK204-25 - Keypad Polling problem with backlight on

Wink · Post by **Wink** » Tue Nov 25, 2003 1:19 pm

I have a LK204-25 with a keypad connected to the keypad connector. I am using a PICmicro MCU to communicate with the LK204-24 via RS-232. I have "Auto Transmit Keypresses Off" as I am using the "poll keypad command" to retrieve the buffered keypresses.

The problem I am having is that with the LK204-25's backlight on, the PICmicro MCU intermittently does not receive the buffered keys when polled. With the LK204-25's backlight turned off, all works great.

Anybody know why?

Thanks in advance.

David

Post by **Henry** » Tue Nov 25, 2003 5:41 pm

post the order of bytes sent to the LCD when you see the problem and we'll try to duplicate it here.

Wink · Post by **Wink** » Wed Nov 26, 2003 1:52 pm

I am providing the LK204-25 with an initial string of:

254, 88, 254, 69, 254, 80, 210, 254, 79, 254, 75, 254, 84, 254, 70

Then during a loop I continuously poll the keypad buffer about once per second with:

254, 38

All works great!

But if I turn the backlight on (254, 66), the PICmicro MCU intermittently does not receive the buffered keys.

Turn the backlight off (254, 70), all works great again!

David