Question on PIC16F877

[taengi]

Hi. I'm having some questions on PIC16F877 IC. I really hope somebody can help me out with this coz it's confusing after study thru datasheet.

1. Is it true that setting Vref on RA3 & RA2 (pin4&5) would help to stabilize the IC? If so, how do I set it? is it just configure it as input port ( TRISA=0x0C).

2. my programmer is showing error "configuration programming error" while I was flashing my program lately. I changed PC, 7407 IC, transistor on programmer kit, check the voltage regulator on the kit, all seems alright. I suspect the parallel port cable would have caused this problem, but is it possible? coz I tried using other programming kit and it did sometimes give this probs but the bottom line is, most of the time it works.

 

[Nigel Goodwin]

Hi. I'm having some questions on PIC16F877 IC. I really hope somebody can help me out with this coz it's confusing after study thru datasheet.

1. Is it true that setting Vref on RA3 & RA2 (pin4&5) would help to stabilize the IC? If so, how do I set it? is it just configure it as input port ( TRISA=0x0C).

Those are only the reference for the anlogue to digital converter, what is your problem?.

2. my programmer is showing error "configuration programming error" while I was flashing my program lately. I changed PC, 7407 IC, transistor on programmer kit, check the voltage regulator on the kit, all seems alright. I suspect the parallel port cable would have caused this problem, but is it possible? coz I tried using other programming kit and it did sometimes give this probs but the bottom line is, most of the time it works.

What programmer and software are you using?.

 

[taengi]

Hi Nigel,

1. My problems is, the PIC sometimes produce the right outcome and sometimes don't. Say, when the power is ON, RC1 supposed to set High and turn on LED, but it sometimes doesn't. When it doesn't, I checked on the Vdd pin, GND pin and it seems ok, it's just the particular pin RC1 didn't set as HIGH. I am not sure if this is software problem. The other day, my senior suggested that I should have Vref for my PIC to stabilize it (that is to set RA2 & 3 as Vref), so I was wondering if setting Vref has anything to do with stabilizing the PIC??

2. About the programmer, I am using EPICWin and MPLAB to write and flash my PIC.

I'm looking forward for your reply. Thanks

 

[Nigel Goodwin]

As long as your hardware is sensibly designed and constructed, then it's almost certainly a software problem. As with any problem, break it down into smaller sections and check each piece seperately.

For proven working hardware (and software for that matter) you might consult my tutorials?.