Electronics > Beginners
Pulling my hair out. Circuit boards stop working once shipped to client and more
Psi:
Have you checked the fuse bits to confirm settings are correct?
- Clock source (often there are different settings for <8Mhz and >8Mhz xtal. If you use the <8Mhz setting for 16mhz clock it works just not reliably.
- Startup delay (set max delay if unsure)
- Brownout setting.
mcinque:
--- Quote from: Jackster ---I have the boards that have failed from when clients used them. More than half worked as expected. Some did fail testing.
--- End quote ---
Sho you had perfectly working boards and now some of them aren't working.
So why don't you trace what's failed in that boards? It's the MCU? It's one of the power rails? The crystal? What else? That is essential! Knowing that would be a huge help.
Please, do it and report it here.
Jackster:
--- Quote from: mcinque on June 06, 2019, 07:54:48 am ---
--- Quote from: Jackster ---I have the boards that have failed from when clients used them. More than half worked as expected. Some did fail testing.
--- End quote ---
Sho you had perfectly working boards and now some of them aren't working.
So why don't you trace what's failed in that boards? It's the MCU? It's one of the power rails? The crystal? What else? That is essential! Knowing that would be a huge help.
Please, do it and report it here.
--- End quote ---
I am not sure what was wrong with them other than the firmware stops running as it should be.
Power is fine, sensor input is fine.
The only thing it could be is the MCU or WiFi board.
mikeselectricstuff:
Only read the first post and skimmed the rest but my guess would be oscillator startup issues - assuming you use a crystal or ceramic resonator. This would be consistent with inability to program and some units working and some not.
There can be a number of causes, bad PCB layout being one, in particular capacitance across the device, as well as non-optimal load capacitance.
A quick fix can often be to add some resistance across the resonator ( 1-10M), or if possible select a different oscillator power - I don't recall the AVR options offhand but many MCUs have drive-level options to trade off power draw vs startup time.
If you have a dead board in front of you, poke the oscillator pins and see if it starts.
mcinque:
--- Quote from: Jackster on June 06, 2019, 07:58:36 am ---I am not sure what was wrong with them other than the firmware stops running as it should be.
Power is fine, sensor input is fine.
The only thing it could be is the MCU or WiFi board.
--- End quote ---
As I (and the wise Mike) said: check the crystal/oscillator. Put an oscilloscope to see if it's working. Keep in mind correct probe range/capacitance while probing.
Also, "power is fine": did you check it with a DMM or with an oscilloscope?
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