Electronics > Beginners
Pulling my hair out. Circuit boards stop working once shipped to client and more
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Mr. Scram:

--- Quote from: vk6zgo on June 01, 2019, 12:00:25 pm ---I remember many years ago, a separate State branch of the organisation I worked for were tasked with making boards that would automatically ring various phone numbers  when required.

We duly received our portion of those devices, but unfortunately they didn't work.
When we complained to the other State, they protested:
 "But we tested them & they all rang up who they were supposed to!"

Yup! They dutifully programmed the whole number needed to call those sites from their State into the PROMs.
Those additional numbers, of course, weren't needed in the State they were intended for, & would "freak the exchange out".

--- End quote ---
I'd argue that's an error on the exchange end, but you'll still have to deal with it.
AndyC_772:
Why have you got reset connected to DTR via a capacitor?

What happens if you remove that capacitor?
ubbut:
Did not read the whole thread just leaving this here:


ATMegaxxxPB devices do not support the 'high amplitude crystal oscillator mode' only the 'low power mode'.
If you set the fuse bits like for a PA device, some will work, others won't. But always unreliably. Usually first programming action is fine, but then they might just be unresponsive..
Cost me ~100 faulty atmegas until the problem was discovered.
NivagSwerdna:
FWIW I have a high value R across my XTAL... no idea why... think I must have stolen the idea from the Uno reference design.

.... but https://forum.arduino.cc/index.php?topic=176297.0 so I wouldn't lose any sleep over that one  :D
oPossum:

--- Quote from: AndyC_772 on June 07, 2019, 11:55:07 am ---Why have you got reset connected to DTR via a capacitor?

--- End quote ---

Copied from Arduino. Not a good design IMO.
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