Newbe Startup Time Question

This depends on the part. If you use the largest FPGA's and a serial loader you could be in the seconds range. Many FPGA's have parallel configuration interfaces if you're willing to give up the I/O pins for it. This can reduce timing to low milliseconds for the whole part or even microseconds if the part can be partially reconfigured.

Lattice has some new parts that are marketed as CPLD's, but are really FPGA's. The MACHXO series allows you to reconfigure the internal flash while the part is still running the previous version. Then you can switch to the new program quite quickly. The largest of these parts has only 2280 LUTs, though. Large FPGA's can have 150,000 LUTs.

If you know how large a part you need to do your job, you can generally find the configuration time in the data sheet. You might find for example that a medium sized FPGA has 2 megabits of configuration data and can load serially at 20 MHz, so configuration would take about 100 milliseconds. There is usually some additional time for the part to initialize itself, but small compared to the serial bit loading.

If you're serious about quickly changing configuration you need to look at parallel configuration methods and partial reconfiguration. Together these attributes can allow you to quickly and seamlessly switch functionality. However expect a lot of headaches in the design process. Google for partial reconfig in this group.

Hope this helps, Gabor

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milliseconds to seconds in worst case, dependig the configuration type and solution being used

Thanks. I'll look around in some whitepapers I got hold of.