PA3 unwanted interupt

howard · ‎2004-08-22

Posted on August 22, 2004 at 18:32

howard · ‎2004-08-19

Posted on August 19, 2004 at 18:45

I am having trouple with an interupt on the pa3 line of a 42 pin st72334j2. The interupt is called even though the option register is zero. If I make outputs of the unconnected pins (ie pa0-pa2 ) the interupt is not called. Why?

alexanderczajor9 · ‎2004-08-20

Posted on August 20, 2004 at 09:39

Hi,

could you specify a little bit more your problem ?

What is PA3 connected to ?

Under which conditions do you get the interrupts when OR = 1. ?

Is the PA3 changing it's potential etc ?

What happens, if you leave PA0-PA2 in reset state configuration, that is

all registers set to ''0'' ?

howard · ‎2004-08-22

Posted on August 22, 2004 at 18:32

Thanks for replying. The PA3 line is connected to a resistor to 5volt and debounce cap. A switch also connected between ground and the pa3 line. Whenever the switch is pressed an interupt occurs even though the option register is zero for the pa3 bit. On a 42 pin device the unused port pin option bits are connected to Vdd. this is because the interupts are anded together.

There should be no interupt because the option is zero for pa3.

regards Norrie