Post by thread:[PIC]: 16C84 RA1 depends on RA2 ?

Hi, i am a newbie in PIC handling/programming. So far i getting few light flashing, but i run in a strange problem. I am using (16C84)on porta (0..3) for output purpose, but the RA1 goes only to a high, if RA2 is also set to high level. If i set RA2 as an input Ra1 reacts fine. A second 16C84 shows the same phenomenon, but such behavior should not happened. So could someone give me a clue what i am doing wrong ? thanks in advance, Thomas -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

Thomas Krampe wrote: > > Hi, > > i am a newbie in PIC handling/programming. So far i getting few light flashing, > but i run in a strange problem. > I am using (16C84)on porta (0..3) for output purpose, but the RA1 goes only to a > high, if RA2 is also set to high level. If i set RA2 as an input Ra1 reacts fine. > A second 16C84 shows the same phenomenon, but such behavior should not happened. > > So could someone give me a clue what i am doing wrong ? > > thanks in advance, > Thomas Thomas, You may be running into the old read-modify-write problem when doing sucessive operations on an I/O port. You may want to look in the data book for a paragraph entitled "Sucessive Operations on I/O Ports" to get the details. Basically, you need to seperate I/O operations with some instructions to allow the port pins to stabilize before performing another operation on them. Hope this helps! Greg Maki -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu