PIC power on problems....

[SnM]

I am using a 12f629, and sometimes when i connect power to my circuit, it locks up.

After I burn the chip, or let it sit with now power for a while, and then apply power, it runs fine, and lights up an LED I have connected to GPIO,0.
I also have an LED on GPIO,1 and 4. GPIO,2 and 3 are inputs, and the pins are NOT floating. GPIO, 2 has a pull down resistor to ground, GPIO,3 has a pull up resistor (2.2K I believe). And reset is setup for internal only. GPIO,5 is pulled up high with a resistor.

If I remove power, and wait about 2 seconds after the LED fades away, sometimes it will not work correctly. I either get:

1. No LED's light up.
2. LED's connected to GPIO,0 and 4 light up.
3. All LED"s try to light up
4. Or it works normal.

What would cause a PIC to not start up okay? Could it be my power supply???? I am using a .1uF cap across the PIC's power and ground. I attached an image of my power supply.... I am not able to double check it now, since I am no where near it, but I believe that is what it is.

Thinking a bit more about it, the errors occur when I have GPIO,3 low (switch activated).......I don't remember the errors happening when GPIO, 3 starts off high. I have the RESET set for internal, but could that still cause a problem?

Thanks!
Steve

 

[Exo]

Did you enable the Brown Out fuse ?

 

[SnM]

no

 

[Exo]

well, try enabling it

 

[SnM]

thanks, that helped a lot!!!

 

[avarachan]

12f629 lock out problem

Hi,

I had the same problem of 12f629 lock out. I found this post about brown out fuse here. It solved the problem. I am writing this just in case any one who needs this info can get it.

Scene: 12f629 with GP0 and 1 as unputs, 2 as output. When I power up, sometimes GP2 starts as high, which i dont want to. Bcz I use GP2 to trigger a switch when GP0 and 1 as comparators give a high out. Again, some times when i Power up, the chip locks out, and no response.

Solution: I was having NOBROWNOUT fuse set. I changed it to BROWNOUT. Every thing is fine now. Thanks a lot, to "EXO"

 

[heyhey123]

What's a brownout fuse? Is it the configuration bit about the brown out detect?

 

[ericgibbs]

What's a brownout fuse? Is it the configuration bit about the brown out detect?

hi,
The Brown Out bit in the CONFIG Register enables/disables the BrownOut detect within the PIC.

 

[heyhey123]

hi,
The Brown Out bit in the CONFIG Register enables/disables the BrownOut detect within the PIC.

So what is the brown out fuse?

 

[ericgibbs]

So what is the brown out fuse?

hi,
A long time ago in some MCU's and OTP [one time programmable] devices the internal 'fuses' were fine pieces of wire inside the MCU/OTP and when the User programmed the CONFIGURATION bits, the fine links were actually fused into the open circuit state.

The term 'fuses' is still used by many people when actually they are talking about the PIC's 'reprogrammable' CONFIG registers..

EDIT:
Look here
http://www.embeddedadventures.com/pages/p/Tutorials/id/43

 

[heyhey123]

hi,
A long time ago in some MCU's and OTP [one time programmable] devices the internal 'fuses' were fine pieces of wire inside the MCU/OTP and when the User programmed the CONFIGURATION bits, the fine links were actually fused into the open circuit state.

The term 'fuses' is still used by many people when actually they are talking about the PIC's 'reprogrammable' CONFIG registers..

EDIT:
Look here
http://www.embeddedadventures.com/pages/p/Tutorials/id/43

Thank you so much for the help