Date: Sat, 6 Sep 1997 01:26:52 +0100 (BST) From: Andrew Gordon <arg@arg1.demon.co.uk> To: freebsd-hardware@freebsd.org Subject: Problems with 16650 UARTs Message-ID: <Pine.BSF.3.91.970906010053.9191A-100000@server.arg.sj.co.uk>
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I have a card with Startech 16C650CJ UARTs which is behaving rather oddly. Initially, I was testing with stock 2.2.2-R, assuming that these beasts were 16550-compatible by default. I later tried 2.2.2-STABLE, and the latter with the explicit 16650 support from -current merged into sio.c (resulting in a sio.c which is the same as -current apart from some stuff to do with COMCONSOLE). All give the same result. The behaviour is that the ports initially work OK, and will transmit or receive continuously without problems, but after a short burst of simultaneous transmission and reception, the receiver locks up such that all received characters are lost silently (Tx continues to work OK). Closing and re-opening the device unlocks it temporarily. Most of my testing was at 115200, but it failed just as easily at 19200. The problem occurs whether or not the port is configured for RTS/CTS flow control. My initial test was with pppd on both ends (the other machine having a conventional 16550). I then wrote a trivial dumb-terminal program for testing (hacked to transmit 1000 copies of each character I typed to generate enough traffic). While this could obviously be a faulty card, the fault is identical on both ports (and the card has two separate 16C650CJ chips, plus a minimal amount of TTL for address decode) so this seems unlikely. Besides ideas for fixes, I would be interested in any pointers to 16650 datasheets (Altavista offers me several companies called Startech that don't make UARTs, and lots of places that sell cards with 16650s on them, but not the manufacturer!). Thanks. Andrew.
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