- From: frank mori hess <fmhess_at_students.uiuc.edu>
- Date: Tue, 4 Jun 2002 23:12:39 -0500 (CDT)
Where did you get the info that the CIO-DAS16/jr doesn't have a fifo? Anyways, you might want to try the cvs version of the das16 driver. It doesn't wait for the dma terminal count interrupt ( in order to work around buggy isa dma on some motherboards) and so is less likely to drop samples. Frank On Tue, 4 Jun 2002, John Conner wrote: > Well I think I know why the CIO-DAS16JR is failing while the PC104-DAS16jr/16 > works. > > The das16.c driver suggests a buffer size that will fill in 1/3 of a second - > given the values > I'm using this works out to 336 scans. Seems a bit familiar. So the driver > has to process a > dma interrupt every third of a second. The one thing I don't have is a number > for is how long > 1it takes to process the dma interrupt. My guess is something longer than 62 > microseconds. > > There is one REALLY BIG but mostly undocumented difference between the > CIO-DAS16jr > and the PC104-DAS16jr/16. The PC104 Board has a FIFO! It does not have any > real > access the way most FIFOs do it just sets in the data path. The FIFO is 512 > samples deep. > The PC104-DAS16jr/12 also has the FIFO. > > What happens is that the boards continue generating samples while the DMA > system is being reset and some of the samples are dropped on the CIO board. On > the > PC104 board they stack up in the FIFO and are eventually read out. > > Looks like current comedi das16 driver will not work at the rates I need with > the CIO-DAS16jr > boards. > > John Conner > Empire Digital Instruments > >
Received on 2002-06-05Z03:12:39