[ECOS] serial driver questions

Kenneth Porter kenneth_porter@kensingtonlabs.com
Wed Mar 1 04:49:00 GMT 2000


On Wed, 01 Mar 2000 12:31:42 +0000, Jonathan Larmour wrote:

> We (Red Hat) are shortly about to start some significant development work,
> part of which will include non-blocking I/O. We're a bit short on
> implementation details right now, but fully intend to develop this in the
> open. We would of course greatly appreciate any input you could give once we
> start, but as announced elsewhere, just now we're pushing towards the
> upcoming new eCos net release.

I'd suggest a "semi-blocking" mode where a configurable timeout
(typically a few character times) would allow a read request to return
when the line remained idle for longer than the timeout. (The better
UARTs with FIFOs have this kind of logic wired to the receive
interrupt.) Making the timeout dynamically configurable is important,
as some protocols (eg. SEMI-E4, AKA SECS-I) require different timeouts
in different parts of a packet. For example, SECS-I specifies one
timeout for the first "wake-up" character in its protocol, but a
smaller timeout for intercharacter time in the data part of a packet.

Kenneth Porter
Kensington Laboratories, Inc.
mailto:kenneth_porter@kensingtonlabs.com
http://www.kensingtonlabs.com




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