Summary: 16F877 Pic acts like it isn't even running at power up. Why? I've used the 16F627 successfully for an almost identical projects, a few switches and a few leds running a state machine. I'm using the PICC Lite 8.0 and the Microcom IDE 6.0. I've whittled the code down to (from 200 lines of what I will go back to when it works) #include #define TRUE 1 /* processor control bits, configuring the hardware before startup 11 disable flash memory code protection 1 disable in-circuit-debug, use RB6,RB7 for i/o instead 1 unimplemented 1 disable flash memory write protect 1 disable eeprom protect 0 disable in-circuit low voltage programming, use RB3 for i/o 0 disable brown-out reset of the processor 11 disable flash memory code protection 1 disable 72ms power up delay 0 disable watchdog timer 11 resistor-capacitor oscillator 11111100111011=0x3F33 */ __CONFIG(0x3F33); main() { TRISC = 0x00; PORTC=0x55; while(TRUE) ; } which compiles to (disassembled and commented here) 0 CLRF 3 ; Select bank 0 1 MOVLW 0 2 MOVWF 0xa ; PClath, clear upper program counter bits 3 GOTO 4 4 CLRF 3 ; Select bank 0 5 GOTO 0x7f7 ... 7f7 BSF 3,5 7f8 BCF 3,6 ; Select bank 1 7f9 CLRF 7 ; TrisC, make PortC outputs 7fa MOVLW 0x55 7fb BCF 3,5 ; Select bank 0 7fc MOVWF 7 ; PortC, make pins 01010101 7fd GOTO 0x7fe 7fe GOTO 0x7fe ; loop forever 7ff GOTO 4 I'm using 5-10k ohms and 25-100 picofarads for the RC oscillator. Scope shows a better RC charging waveform and a better /4 oscillator output from the part than I would expect, frequency varies exactly as I would expect when I change R or C values. I've got decoupling caps, I've got stable power supply with correct polarity connected to all VCC and gnd pins. I've got all outputs connected to ground via 1k ohm. I've got an RC circuit for MCLR and have tried manually holding it low for several seconds before letting it pull high. I've manually stepped the code through the simulator and watched all the instructions do exactly what I would expect, showing that port C is loaded. I've got the IC-Prog 1.05 software and the PG2B programmin hardware. It happily recognizes the part, programs it, confirms the program and will do this again and again. And when I drop the part into the protoboard... all the pins except OSC in, OSC out and MCLR remain happily at zero volts. Loading ports A, B, D, exactly the same non-effect. Lifting the pull-downs, same non-effect. I've searched the mfgr's web pages, I've searched the piclist web pages, I think I've followed every recommendation. I've asked a few folks outside the list, they have come up with a few ideas, disable delays, manually hold MCLR, check code in part, terminate all pins, don't terminate all pins, reprogram the part... I've tried each one. Exactly the same non-effect. All the port pins sit at zero volts, but not pulled down hard enough to sink current and, say, light a led. Can anyone offer an idea what might be wrong? Or what to try? Thanks dont@agora.rdrop.com (valid, if that matters and message isn't important enough to broadcast to everyone) -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics