> > To be honest, after using the GPIF designer a few times I was sorely tempted > to write a bunch of macros to generate the GPIF data words :-/ >
After using the gpif a bit, my impression was that everyone switched to slave fifo :). I suppose the gpif can be used for some specific cases, but it had severe limitations if you tried to do anything but what it was specifically designed for. We even went as far as to try to get Cypress to help. They had engineers look at it for weeks, saying it was possible and about the time I had learned everything the Cypress engineer knew we came to the conclusion it wouldn't work. (I felt like I was teaching the guy at the time.) Anyway, basic use case: Read data from your slave device, through the gpif, to the computer right. So far so good. A signal state, a read state, transition though idle, repeat for number of bytes to read. Easy enough. Add requirements, read fast.. (Transfer data at max trans rate). So far so good, gpif can clock on rise and fall.. As long as you're transferring less than one fifo buffer size you can make it work. Add requirement, hold data off in case of computer slowness or while swapping fifo buffers (and do longer reads) Doh, it's a no go. You need a state in the gpif with multiple output states. Can't be done. The closest I ever got was to implement a state machine in firmware that started and stopped the gpif for every fifo buffer. (512 or 1024 byte reads). It couldn't transfer data at 43MB/s though. (I think I got up to 33MB/s or so if I recall). To make matters worse, Cypress won't provide a verilog behavioral model so that you can try to get a simulation working. Debugging was a pain. So, to make along story short: Slave fifo solved the issue. ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Fx2lib-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/fx2lib-devel
