Well, That’s right there is a probability to miss some non crucial packets. Actually even in other protocols like isochronous USB there is such possibility. There are ways to prevent this (for example by adding a packet id), but for my project many of data packets are update information and it’s not very important to lose some of them. As I said before ACK and NACK have multiple purposes and CRC check is one of the purposes.




How will you determine that the packet you lost is not crucial as you have no way (unless you add packet-id's and copy the packet id in the ACK or NACK) to determine which command was akced and which one was not?

If it's not important to miss some packets, you may just as well get rid of your ACK, and (silently) drop the packet if the CRC doesn't match.

If you can do without some of the packets, is it necessary to use a fifo in the first place? After all you wouldn't be sending more than than 15 Bytes per second. (If I remember correctly). I think if you cannot spare 15 times a second a few microseconds to read and buffer a data-byte, you may be in need of a faster processor...


Regards

Patrick