- From: Frank Mori Hess <fmhess_at_users.sourceforge.net>
- Date: Thu, 7 Nov 2002 15:29:29 -0600
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Thursday 07 November 2002 11:51 am, Daniel Koch wrote: > Hi Frank, > > how do I use this `timer mode` option ? Isn`t there a way to modify cmd or > mmap so that it does hard-realtime ? > Daniel, Its one of the options you pass to comedi_config, I forget which one exactly. It is listed in the top of the das16.c source file, and in the comedilib board-specific documentation. You can't do hard real time interrupts with isa dma because you have to aquire a spinlock before accessing the motherboard's dma controller. Hard RT interrupts can't safely access the dma controller because they don't respect ordinary spin_lock_irqsave() type stuff. I'm assuming your problems are due to the board's hardware fifo filling up while it is waiting for the dma terminal count interrupt to be handled (although your comment in another message suggesting the errors were related to how big comedi's read buffer is would suggest otherwise). The timer mode thing periodically interrupts the dma transfer instead of waiting for it to finish, so there is less of a latency problem. Maybe your problems aren't hardware related though. Are you just seeing a problem when you reach the end of comedi's buffer? Maybe you are just trying to do mmap access and not marking any of your data as read, so comedi thinks you have lost data? - -- Frank -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE9yts75vihyNWuA4URAuXkAJkBUg6iEL9DCYbKHkJ6NgbVEqxhDwCg58qW OLHgBDuQXiz6pMgFLupIzwg= =Ei2D -----END PGP SIGNATURE-----
Received on 2002-11-07Z21:29:29