Problem with PIC16F87

[Acetronics2]

Hi,

I thought it was a 16F88 ... sorry !

Did you install the 0.1µF close to the '87 supply Pins ( between pins is best ! ) ... and a 10µF+ Tantalum as close as possible ???

Some decoupling might be also necessary for the 555 : there are well known current spikes while the output stage toggles ... or try a CMOS 555 !

Alain

[The Master]

I think i have a 10nF cap right at the side of the chip. Its as close as i can get it. There is also a 100uF cap right after the regulator. Theres also an audio circuit that connects to it which has a pair of 1000uF caps on i think (they are at least 100uF). It doesnt make any difference wether or not that circuit is attached.

I didnt use a CMOS 555 because i read somewhere that they wouldnt be suitable for this circuit.

[The Master]

Hi, Im still having problems with this one. I connected the circuit back up to have another go at fixing it but the PIC doesnt seem to work properly at all now. When the 555 isnt connected the chip will turn on and flash some LEDs (to show its alive) then after a few seconds it resets itself. With the 555 connected it does the same thing but flickers slightly during the flash pattern.

I connected my picoscope up to see whats happening. Ive uploaded a screenshot of it. This is with the audio circuit (with the big capacitor) disconnected and with the 555 connected. This is the most variation the circuit could possibly see but it doesnt look like its enough to cause any problems

[mackrackit]

What are you using for a power supply and how is BOR set?

[The Master]

Im using a PSU similar to ones that would power external hard drives etc. Ive run breadboarded PIC circuits from this before without having any capacitors so i know its a good supply.

Something i forgot to mention before, the manual for the picoscope says that it will pick up slight interefence so the voltage is probably a lot cleaner than that line makes it look.

BOR is a fuse value right? I think ive seen it before but this chip doesnt seem to have that fuse.

Ive uploaded a screenshot of the fuses i have available and their values. Its been about a week since i last programmed this PIC so maybe a fuse is wrong

[mackrackit]

BODEN or something like that for this chip. Sorry

[The Master]

I tried changing the BODEN value but i got a fuse error that i cant get rid of. Ive set the fuses back, turned the programmer off/on and restarted the program but everytime i try to program i get this error "Fuse error 0x2007, Good 0x3F6E, Bad 0x0F0F". The numbers change when i change the fuse values though