16f877 Unused Pins

[mister_e]

having some resistor to pull them down have it's own advantage in case the software goes crazy, if you alter the TRIS setting by inadvertence, or while developing/debugging. Kinda bullet proof

[hvacrtech]

I use LCDOUT with DB4-DB7 on PORTB.0-PORTB.3, RS on PORTC.1, Ebit on PORTC.0 on 16F886. Starting BIT is set to 0. Will setting TRISB and TRISC even not set correctly can damage the LCD as well the PIC itself?

example TRISB=00000000 and TRISC=00001111 as used before, works fine till I noticed something that TRISC shows last four inputs and I changed it to TRISC=00000000, the result is damaged. all are set for DIGITAL Modes (ANSEL).

Does it have to have TRIS set correctly for use with LCD?

I have about ten units running fine with TRISB=00000000 and TRISC=00001111 working fine, then the two units failed with modified TRIS's TRISC=00000000. Maybe the TRISB needs to be 11110000 and TRISC set to 00000011?

[hvacrtech]

I use LCDOUT with DB4-DB7 on PORTB.0-PORTB.3, RS on PORTC.1, Ebit on PORTC.0 on 16F886. Starting BIT is set to 0. Will setting TRISB and TRISC even not set correctly can damage the LCD as well the PIC itself?

example TRISB=00000000 and TRISC=00001111 as used before, works fine till I noticed something that TRISC shows last four inputs and I changed it to TRISC=00000000, the result is damaged. all are set for DIGITAL Modes (ANSEL).

Does it have to have TRIS set correctly for use with LCD?

I have about ten units running fine with TRISB=00000000 and TRISC=00001111 working fine, then the two units failed with modified TRIS's TRISC=00000000. Maybe the TRISB needs to be 11110000 and TRISC set to 00000011?

AFter reading other forum, I put default for the programmer U2 and the problem solved! Now that my completed unit is back to life! The TRIS has to do nothing with for using with LCD but the unused pins information is excellent source for terminating unused pins via pullup or pulldown. I ususally set TRIS outputs for unused pins.

[Archangel]

The TRIS has to do nothing with for using with LCD but the unused pins information . . .

I imagine . . . LCDOUT sets the tris like the HIGH and LOW functions do. Dig through the library if you are really curious to find out.