I have a project with 14 bidir. I use to test integrated circuits from college.i use the 36 gpio pins in a protoboard with a flat cable. but when i put the bidir in high impedance, all outputs go to high level (but they continue in high impedance).
Firstly i think the weak pull-up resistor is on (and turn off). After I tried turn off all programmable adjustments. Nothing worked. I am a computer scientist and maybe my fail is in eletronic level. I don't know. Any suggestions? What can you do to help me?
--- Quote Start --- What is driving the wire when you put the FPGA pins in high impedance? --- Quote End --- The GPIO is connected to protoboard (flat cable). I didn't understand your question, but nothing is connected between pins and protoboard when are in high impedance. https://www.alteraforum.com/forum/attachment.php?attachmentid=6918 FPGA >> PIN <> GPIO <> Protoboard
--- Quote Start --- Since there isn't anything else driving the wire, when the bidir signals go into high-impedance state, the status present in the wire is "random". --- Quote End --- So, why can I do?
--- Quote Start --- So, why can I do? --- Quote End --- What's the problem? If you need them low add very high value pull down resistors from each line to gnd. ? Nial