Dear friends, The Real problem is, i need dma to fill codec controller FIFO in every 600us(8 samples still in codec FIFO and codec controller is half full, at that time it will generate interrupts), this will generate a sin wave which is used to controll another device. If codec controller did not get data in this period it sents last available sample again and again, thus producing a straight line. In Normal linux (2.4 kernel) interrupts and process scheduling may cause problem. This is the reason for porting linux audio driver to RTlinux and it is not possible to access normal linux driver from RTLinux threads. Nobin Mathew __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com