On Sat, 22 Oct 2005 21:48, Bernd Walter wrote: > That's the big win with 9 bit. > Modbus uses 8 bit so each controller has to actively listen. > The RTU variant uses fixed idle times to mark packet ends, which is > hard to do right in kernel and unreliable to do from userland. > Since I needed multi-OS support and have at least one customer with > many busses the kernel was no option.
Fair enough. Your solution sounds very flexible and useful! > Don't know about line discipline abilities, but I remember that some > trustfull persons declared this to be doable. > It is the whole hardware design that won't fit. > As long as timing is not critical and you have legacy serials it is OK. > But many USB uarts don't have native 9 bit support as well, and the > nature of USB is that you really want large FiFos. > This is a dead track IMHO. Yeah, I think the line discipline approach is feasible with legacy hardware, but USB makes it difficult to do. > The whole thing is suboptiomal. > Today there are no reasons to not offload the tricky parts into > external devices. Heh, apart from dev time :) > I'd originaly used Atmel Mega8 plus Philips PDIUSBD11 for this. > It was a slow but reliable and cheap combination, but Piliphs stopped > production of the chip. > Today I use Mega64 and PDIUSBD12 for USB and Mega128 with RTL8019AS for > Ethernet, which gives me two UART for use in a single device. > The controller have 9 bit wide FiFos. > If you are already in the 8051 world, you might look at TI TUSB3410. Ahh looks interesting. I have used Atmel a bit to play around with it.. I have some sample 3410's but haven't even assembled the test board I made :-/ -- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
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