18

As others have said, you shouldn't have a problem as long as you double check your code. If you do get it wrong, by and large the ATMega IO pins will limit themselves to about ~80mA due to internal resistance of the MOSFETs (value found by experiment). This is not good for the chip, but as long as you don't leave it in this condition for an extended period,...


11

You should be cautious but not terrified about it. Setting a pin output and driving it to the other direction will cause a lot of current to flow, but it also does not blow up in smoke immediately. You could for example power the device with current limited labotatory supply when bringing up a design so these kind of errors cause even less damage. I'd be ...


9

Considering this type of circuit is avidly encouraged, how it doesn't seem to bring any troubles? Because when engineers set up the I/O for their device, they are careful to ensure that they do not drive inputs as outputs. For most I/O, we will set pins as either inputs or outputs at startup and never change them later. This gives us only one line of code ...


4

Can confirm, on an arduino uno, 328p chip, if you connect a driven output to ground or VDD, it will kill that pin. I have accidentally done it several times in my early days with electronics. On other chips I work with, I'm pretty careful not to do this but more modern ones do seem less susceptible to this failure mode. For example, I accidentally set up a ...


3

I noticed is a "jerk" to 7805 did it Any interruption in the 7805's ground connection would result in the 12v input being applied to the downstream circuitry, resulting in immediate damage. You really need to arrange things such that a "jerk to the 7805" is not possible, ie, solder the connection or use a good connector in a way that it is not under ...


2

The zener diode is connected the wrong way. Instead of being in series with the atmega it has to be in parallel, with the cathode connected to 5V and the anode connected to ground. In your case you don't really need a zener diode, because the 7805's voltage should be pretty stable (linear regulator) and I would say "paranoia" is not an argument ;). That ...


1

Simplest way is to add another regulator, but it has to be an LDO regulator, not a 7805. For example, the AP2210N-5.0TRG1 has only a few hundred mV drop at 100-200mA and can handle up to +15V in. It's advertised as being able to withstand negative inputs as well, but I don't see a specifically stated voltage limit on that. Be sure to use the recommended ...


1

I don't see how it can even work to begin with. Based on the schematics, the AVR is completely missing the AVCC power supply connection. And lack of proper bypass capacitors at AVR supply pins can cause problems too.


1

The circuit worked all fine until 7805 was moved a bit by jerk and all becomes hell, atmega stops. Is it permanent damage? I am unable to understand what is it and my money is wasted on buying new chips and demoralizing me to continue. 'Jerking' the regulator should not have any effect, unless one or more pins has a poor connection. If the GND pin ...


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