At 10:44 AM 5/30/00 +0100, Andre wrote: >Hi all ! > >I«ve been working on a CPU used to control a high teperature high pressure >chamber based on a 16C622A. >It has a LCD display (16x1) been drived using nibbles instead of 8 bits >words. Unfortunatly I have no more free I/O pins to use. >The problem is as follow: >1. When I first turn the CPU ON everything goes right. The LCD shows the >message it was programed to show. >2. If I turn the CPU OFF and not after one or two seconds back to ON again >the LCD shows anything but the message it was programed to show. >3. If I wait a little bit more (5 sec.) before turning the LCD back to ON >again everything goes right. >4. If I turn the CPU OFF and back to ON two times without wait all goes ok. >I am sening the data without using the LCD R/W pin. The data is sent to >the display and the program waits it to stabilize before sending the next >4 bits. My off the cuff suggestion is that you are not properly initing the LCD. According to specs, you must issue the 'switch to 8 bit mode' *3* times before switching to switching to 4 bit mode. Repeat: you have to issue the 'function set' command with the 8 bit mode bit set for a total of THREE times before changing to 4 bit mode. You would do this in your PIC init routines after each power up reset. Give it a try! dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 16 years of Engineering Innovation (1984 - 2000) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email.