Problem with unused pin I/O in EPM7128 project

[wwwrabbit]

pin I/O

I use MaxPlus did a small project. choose device EPM7128, assign pins and systhesize is OK, load to EPM7128 and run. it functions ok. but I found there are some unused pin (I did not assign them ) also have signal output. Why? (I suppose that all un-assigned pin is in high impedence state) and how to sovle it?

Thanks :?:

 

[brmadhukar]

Re: pin I/O

Hi,
Since the pins are not used it cannot be forced to high impedance state. You may use sume dummy (read waste) logic and force these pins to high impedance.
Madhukar

 

[AXE]

pull it up or down with resister

 

[kib]

Re: pin I/O

check the place & route report for Number of LOCed External IOBs
u may have left some ports in ur top module without any pin assignment

 

[ifarmer]

In maxplus, used pins are tied to low. You had better assign these used pins as input.

 

[James Hu]

Re: pin I/O

I guess you use 7000S.
7000S/3000A is different with 7000AE
In MP2,if you choose 7000S/3000S,unused pin is an output of a internal node. Perhaps is low,perhaps is high. If you hope a tri output,you should define this pin as an input . If you want to get a 1 or 0,you also can define it in your design.

if you choose 7000AE,unused pin is driven to the GND.

In QuartusII,you can choose GND/Vcc/Tri/internal output/ for unused pin.