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Valued Contributor III

MAX-II Input pins never detect a LO

All, I tried to post this in the Quartus II and Tools discussion but I have never received a response. 


My Setup: 

Quartus II 9.0 


Schematic entry 


Also, now I have tied a few pins together. Such as: input pins 27,28,29,30 and output pins 108, 107, 106, 105 respectively. So pin 108 should follow pin 27...etc..... but..... it doesn't. 

NO matter how I have programmed the input. TTL... CMOS... Schmitt... with pullups.... without pullups...... all 6-different ways. 


I have tried several different pins and have tried 2 different PLDs. 

I have tried putting latches on the inputs and clock them with a 30MHz clock to see if I can capture the pin input.... but ..... no avail. 

Some of my other input pins seem to work, and I have tried to set up these pins exactly as the ones that work, but NO JOY. 


For the most part the other functions of my design are working as expected, just this 4-bit address comparator to the CHIP_ID address section doesn't seem to be wanting to work. 

The only way it works is if all 4-bit inputs are HI and or floating, so only address oxF (15) will work. 


Am I not setting up my "Assignments" correctly or...... 





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Valued Contributor III

Is this your own hardware or a development board? 

I think you're going to need to post your project here for us to have a look at and, if appropriate, some schematics. 



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Valued Contributor III

Hi Alex, 

I did post the schematic on the posted link.... but..... I changed my CHIP_ID and addr_rd inputs to pins 1-8 and all things seem to be working. They all still go to the same I/O bank as before (pins 12-15, 27-30), but now they seem to be working. 


Also, it was my own "development board" that I have used for numerous other projects. I just have a 30MHz crystal for my clock on pin 18 (my normal's are 20 & 30MHz) and MAX6412 (uP Reset) on pin 61. 


but anyway, I will mark this up for experience and see about shifting pins around next time. 


(now I have a harder time to layout my PCB) 


Thanks again, 

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