- From: Frank Mori Hess <fmhess_at_users.sourceforge.net>
- Date: Thu, 13 May 2004 17:53:15 -0400
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Wednesday 12 May 2004 12:56 am, Alex Fielding wrote: > When I issue a command to start analog output DMA, my data is output, > however I receive the error: > > ni_mio_common: DMA underrun > > what does this mean? It means there weren't enough samples in the buffer to be sure the card didn't dma some garbage into its output fifo. By the way, if you're still trying to do memory-mapped output, it won't work due to the lack of a comedi_mark_buffer_written() function (there is a comedi_mark_buffer_read() for input). It would tell comedi you've put data into the buffer. Alternately, a way to disable under/overrun detection would make it possible. > Should I be able to poll the # of bytes output on the DAC using > comedi_poll & comedi_get_buffer_contents? They return zero for the DAC > subdevice. They return the number of samples sitting in comedi's memory buffer. - -- Frank -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) iD8DBQFAo+5L5vihyNWuA4URAgfgAJwL6hj+ssIr9mgznBhWkmKtUYGIZQCfZ+c6 LwhL+/SmAJ3tSdnU8131nTw= =w4U2 -----END PGP SIGNATURE-----
Received on 2004-05-13Z20:53:15