I'm a novice to programming microcontrollers. I've done some projects during my engineering education and found it very interesting, so I found my STK 200 kit with an AT90S8515 chip on, to start learning some more programming on my own.
I've written some small programs, for manipulating the LEDs on the board, using the cvavr c-compiler. After compiling and programming the chip, everything seems fine. The LEDs are blinking, but just for some seconds, sometimes allmost a minute, then it goes dark or only a few of the LEDs are blinking. After a while it sometimes starts blinking a few LEDs again. When I turn off and on it sarts OK but fails again after a short while.
When I measure the voltage on the Pins it seems like the 8515 is having trouble to sink. The voltage dropps only from 5,00 volt to 3.72 volt, measured with a Fluke 89.
Usually it seems like the program is still running, as the voltage goes to 3.72 volt when the LED was supposed to light, and back to 5,00 volt when it should turn off. but sometimes it stalls.
The short period it works, the voltage drops to 0.62 volt. I'measured both the supplyvoltage and the ground, and they both seems stable on 5.00 and 0,00 volts.
One thing I found a bit strange is that the controller resets when i measure the !reset pin.
Please! have anyone experienced this before? Anyone having an idea what might be wrong?