AVR-Chat

Apologies if I'm stating the obvious, but have you ensured all power and gnd pins on the device are properly connected? And scoped out the power supply to check for noise? Spikes on the PSU could cause that.


-- 
Tim Mitchell

Well, you are stating the obvious, and no apologies are necessary. I replaced an undersized bypass cap (0.1uF) with a bigger one (4.7uF), and the problem is gone.

Thanks.

> -----Original Message-----
> From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On
> Behalf Of Tim Mitchell
> Sent: Friday, September 16, 2011 4:02 AM
> To: AVR-Chat@yahoogroups.com
> Subject: RE: [AVR-Chat] Re: Mega644 Brown Out Detector Problem
> 
> Apologies if I'm stating the obvious, but have you ensured all power
> and gnd pins on the device are properly connected? And scoped out the
> power supply to check for noise? Spikes on the PSU could cause that.
> 
> 
> --
> Tim Mitchell

(Re-sent the below as it got lost apparently? Glad you're fixed up, though I'd leave the 0.1 uF cap there and add the 4.7 uF in parallel with it; Power spike and oscillating VReg problems are a PAIN that I avoid by using too many bypass caps :))

If the LDO Regulator isn't bypassed properly it can oscillate, that could cause the Brown Out Reset to be firing when it drops, possibly? (If you don't bypass properly, it will bite you, it's bitten all of us probably LOL)

Long day so that's all that I can think of ATM.

  Mark

--- On Fri, 9/16/11, Phillip Vogel <phillip@bartal.com> wrote:

> From: Phillip Vogel <phillip@bartal.com>
> Subject: RE: [AVR-Chat] Re: Mega644 Brown Out Detector Problem
> To: "AVR-Chat@yahoogroups.com" <AVR-Chat@yahoogroups.com>
> Date: Friday, September 16, 2011, 10:14 AM
> Well, you are stating the obvious,
> and no apologies are necessary. I replaced an undersized
> bypass cap (0.1uF) with a bigger one (4.7uF), and the
> problem is gone.
> 
> Thanks.