In SX Microcontrollers, SX/B Compiler and SX-Key Tool, tdg8934 wrote:

Harrison,

I tried inserting PAUSE 10 all the way to PAUSE 1000 between every statement in the Initialization_8255 and PortA routines. I have also increase the PULSOUT WR_8255, 10 to various high and low ranges. I have checked and rechecked the 5 control line wires over and over and they are correct as the PIN statements have stated. I have changed values of RB and RC from $00 to $FF and $FF to $00 many times over now to look for changes. I always turn up with no output on the LEDs. I know he 8255 works as I have a BS2 connected to another 8255 runing an almost identical program (with no PAUSE statements like the SX-28 has) and it runs great producing the pattern statement code on the LED outputs.  I can swap the 8255's between the BS2 and SX-28 circuits and the SX-28 circuit never produces any LED outputs. However, the SX-28 8255 (when swapped over to the BS2 circuit) works fine. So I know the 8255 circuit works. I can also connect a multimeter to the SX-28 pins and produce various HIGH and LOW statements on all t
he 

I have changed so many items in the SX-28 code, I don't really know what to look at next. It does sound like a timing issue and Metron9 will be sent 2 8255's to recreate what I am seeing here on my BS2 and SX-28. He has a scope to look at timing issues so maybe we will learn something a week from now. However, in the mean time I reach out to the Parallax community to see if they have any sugestions to try since it clearly seems to indicate a problem with the SX-28 coding and not the 8255. 

Thanks again!

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