Hi Andre! You might want to check the supply voltage to the processor. With some capacity in your system supply voltage will not be immediatly 0 V when you switch of the supply. Let's say the voltage will be 2.0 V when you switch on the supply again, a brown - out will occur. i.e. the processor is plain not running due to the fact that the Vdd didn't reach 0 V... i've seen this in a consumer product (vacuum cleaner). When programming your device be sure to set brown-out detect on (and maybe adapt your program to this). By waiting longer before switching on the supply you make sure that Vdd will reach 0 V, and thus a brown-out will not occur..... Regards, Jilles Oldenbeuving jilles@rendo.dekooi.nl -----Oorspronkelijk bericht----- Van: Andre Aan: PICLIST@MITVMA.MIT.EDU Datum: dinsdag 30 mei 2000 15:53 Onderwerp: [PIC] LCD driving trouble 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. Any comments or sugestions are welcome !!! Andre acolling@zaz.com.br