EPF10k10 reconfiguration

[Altera_Forum]

Hi! 

 What's the best way to perform a reset / reconfiguration on the EPF10k10? Looking at the configuration appnote (AN59, page 4) I'm guessing it's as simple as pulling down nConfig which would force a reconfigure.  If so, this would nicely perform a system wide reset :-)  -Mux

[Altera_Forum]

Hi 

exactly - the rising edge at the end of the low pulse at nConfig (re)starts the configuration process..

[Altera_Forum]

Great! Thanks! 

 -Mux

[Altera_Forum]

Using nCONFIG is overkill though, since it forces reconfiguration of the FPGA. If you have any external devices relying on the FPGA I/Os being in a specific state, then since the I/Os will tri-state (or pull-up) during reconfiguration, you'd have to be careful about having pull-downs on any signals that needed them. 

 If all you want is a reset, then you can just use a reset input (ideally routed to a global input pin on the FLEX10K series).  However, overkill maybe what you're after ... :)  Cheers, Dave

[Altera_Forum]

Yeah, it might be little overkill :-) 

 That said, it's an easy way to get everything re-initialized. The Z80 will run at about a quarter of the clock speed so any I/O operations will be handled by a state machine. While I could dedicate a global (thanks for point that out btw) pin as a reset, it'd mean I'd have to wrap every block with an if (~reset). No big deal, but still..  I'll give it some thought though as I'd still like the clock-divider to be moved into the FPGA rather than have it as an external counter..   -Mux  P.S. The Z80 will also tri-state all of its pins during reset, so we're all good :-)

[Altera_Forum]

--- Quote Start ---   I'd have to wrap every block with an if (~reset). No big deal, but still..   --- Quote End ---    I'd recommend doing that anyway.  When you simulate a design, its nice to use reset to initialize the system - multiple times during the simulation if that is what you are trying to test.  If you do not have a reset signal, then you need to initialize all signals, so that the simulation does not start with them all in an unknown state.  Anyway, its your call, I just figured I'd point out why you might want to use reset ...  Cheers, Dave

[Altera_Forum]

LOL - Yeah, you're right.. Thanks for the post! 

 -Mux