question about lcdkb

morebudwiser · Joined: 17 Oct 2005 Posts: 26

hi could some explain why when i run the lcdkb example when i press a key the number is displayed on the lcd for only a few seconds before disappearing. i though that each key press should be displayed on the next postion of the lcd and the previous keypress should still be displayed until the * key is pressed to clear the lcd.

many thanks for any help given

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

It sounds like a power supply problem. Possibly. Check the +5v on
your LCD and make sure it stays at +5v, and doesn't drop down to
a lower voltage.

Guest · Posted: Tue Feb 28, 2006 2:34 pm

hi i am using the 5v from my debugger to power the circuit do you think i need to use an external 5v. and is it ok to connect an external 5v when you have the debugger connected

many thanks for any help

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Guest · Posted: Wed Mar 01, 2006 5:02 am

hi i am using the ccs debugger so i downloaded the hex to the chip and run the target board from a bench psu and measured 5.05v on the lcd supply rail and get the same result the lcd will display ready... and when the key is pressed the value is displayed but for only a few seconds. dont think its a voltage problem as the whole lcd does not blank its only the second line were the keypress is being displayed. the only thing is i have modified the kb driver from 3x4 to 4x4 and have it connected to port c

many thanks for any help

morebudwiser · Joined: 17 Oct 2005 Posts: 26

hi got it sorted the problem was that the watchdog was enable in the headerfile so the watchdog time out and reset the pic thus clearing the lcd many thanks to pcm programmer for your help