Hi Nick
Thanks
With a suitable state machine you can throw away bytes as they arrive. The only real point of the serial buffer is to allow a margin for error if you can't empty it as fast as the data arrives.
Exactly
As I said I'm receiving updates at 10Hz so need 38.4k if I want to capture all the data, I'm not doing any waiting or delays etc but when I write to the SD card it sometimes takes quite a time before it returns, possibly while its updating the FAT or something, because its periodic possibly after a 512 byte block or something. There is no silly reopening and closing of files etc. Its during this time the buffer overruns and I DO NOT want to throw away data. I did upgrade to a class 4 card that alleviated the problem a bit, but don't have anything faster at the moment to test with.
... Simon