Hi.
I'm trying to implement an external reset on the xmega. I want to reset the device when pressing the reset button but I dont knwo how to check if reset button is pressed or how does the device know that!
Here is my reset button on pin 90 of xmega.
Xmega128a1 external reset
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Reset is handled in ATxmega128A1 hardware. Drive the pin low and it will reset. (Assuming you haven't programmed the reset disable fuse.)
Are you using a PDI programmer?
If so, DON'T use the above circuit, as the PDI programmer won't work, or will work very unreliably.
One can often put a small cap on the reset pin an a Mega, or Tiny, and many ISP programmers will work.
On the Xmega the impedance on the two programming pins as to be equal. Putting a resistor and a cap on one pin makes them very unequal.
If this is for a simple push button switch, pressed by a person, just connect the (normally open) push button switch from the reset pin to ground. Press to reset.
It may bounce a bit, which (generally) doesn't matter.
If another chip is resetting the Xmega, then the signal goes low to reset the Xmega. This circuitry can be a bit more involved so that it doesn't interfere with the programmer.
JC
Im using JTAG (mk II). I also want the reset button to be activated when I hold it down for 10 seconds. Is that possible to program?
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Im using JTAG (mk II). I also want the reset button to be activated when I hold it down for 10 seconds. Is that possible to program?
I think the "easiest" way to do that is to put a push button switch on a normal I/O pin, (with the internal pull up resistor active).
Using either a "normal" switch debouncing routine, or an ISR set up specifically to read this switch, when it has been pressed for 10 Sec then execute a watch dog timeout to reset the micro.
The Xmega has priority interrupts, so one could make this a high level priority, if needed.
The bottom line is you don't use the Reset\ Pin to implement this function.
JC