Wasn't sure if this should go here or in the micro-controller section. Since its a pretty basic question, i'll put it here.
I have been having a problem with one of my projects where the atmega328 micro-controller will spontaneously die. I'm in a bit of a hurry, so I havn't tested them to see what exactly happened (and I have a bin of new ones, ready to be sacrificed), but at some point during use they will appear to reset and then stop running code. If I try to upload new code I get one of the generic avr errors that basically means "cannot communicate with the chip".
After frying the second microcontroller, I did some testing, and found that the 5v switching regulator that am using is actually putting out a consistent 6.01v. Could this be the culprit? Max operating voltage is listed at 5.5v atmega328, would 6v allow it to operate for a short period of time before burning out? Or do switching regulators operate in a way that may interfere with my digital multimeter, similar to "phantom voltage"?
CrossRoads:
Absolute max is 6.0. If you're seeing 6, there's a good chance higher is occurring too.
I just tested the LM7805 regulators that I usually use, and saw a voltage of 5.89v. This is without any load though, just the regulator in a breadboard with my meter attached to it. Maybe my meter is bad?
CrossRoads:
Could be - out of calibration?
Do you have caps on the 7805 per the datasheet?
I did not when I tested it in the breadboard. The switching regulator was tested in circuit and did have all the required caps though. I just remembered that I had one of my old meters in my truckbox, and tested everything using that. Both regulators showed right around 5.0v, so it looks like theres just something wrong with my multimeter. Now I just need to figure out whats going on in my circuit.
I guess this topic can be closed now. I don't really want to get into troubleshooting the rest of the circuit, as i'm being paid for the work and it wouldn't be right to ask for free help.
Due to a mislabelled linear regulator I once ran a 328 at 8.5 volts. This was a breadboard arduino not an UNO, etc.
The sketch acually ran although reset after 30 seconds. After 3 repetitions, I became suspicious and did measurements.
After replacing the offending regulator(which was terminated with extreme prejudice) the 328 worked perfectly with no sign of damage.
wizdum:
I just tested the LM7805 regulators that I usually use, and saw a voltage of 5.89v. This is without any load though, just the regulator in a breadboard with my meter attached to it. Maybe my meter is bad?
Generally linear regulators need a few mA of current to go into regulation. Measure across a 1kOhm resistor to see it's proper output.