What I need to do is very simple for test purposes only. I need to make both of the ports outputs and then write a square wave into them at about 1 second rate.
I have an ATE system that I can use to set up data lines and write pulses and the like. I just have no experience in using the MC6821. Is there anyone who can give me the a simple explanation like... put this word on the data bus, pulse the enable, then put this on the data bus, pulse the enable, and so on so I can use the ATE to generate the square waves I need. I can do all the ATE programming, but this MC6821 has me stumped on how to use it. H E L P M E .... S O M E B O D Y
Hi there,
I feel your pain and have struggled with learning the ins and outs of the 6821 PIA IC.
These page might:
http://webpages.charter.net/coinopcauldron/piaarticle.html
http://www.eee.metu.edu.tr/~cb/e447/Chapter%206%20-%20v2.2.pdf
http://notes.ump.edu.my/fkee/FADHIL%20ABAS/BEE2223/14_Parallel%20Interface.ppt
When you saythings like "write a 0D to the control register" it is virtually meaningless to me because I don't know the proceedure. This is a very confusing chip for the novice to pick up. I've been doing micro's for quite a while, but this data sheet stuff is written as if one plumber is telling another plumber how to install a sink. Both plumbers pretty much know how to do it already. I need someone to help me as if the plumber was telling a shoe salesman how to install a sink.
I there a way for anyone to write simple instructions like;
1- put [0d] on the data bus
2- pulse the [e] line
3- put [14] on the data bus
4- pulse the [e] line
and so on. What I want to do is simply make both ports output ports. I need to then succeccively write all 1's and then all 0's to both ports. THAT'S IT!
I have no familiarity with, or access to any motorola 6800 equipment, but my ATE can create any 8 bit word I need and any kind of positive/negative pulses and address lines you tell me to create.
I feel like such an A-Hole because I've beeen going over the data sheet again and again, and I can't grasp how you address different registers that have the same address.
When I finally see how it's done I know I'll feel even worse, but my back is against the wall because I have to ship this controller board to the U.S. Army, and my time is just about all gone.
Can someone please help me.