Path: utzoo!attcan!uunet!ginger.acc.com!ivucsb!todd From: todd@ivucsb.sba.ca.us (Todd Day) Newsgroups: comp.dsp Subject: Re: More digital mixer stuff Message-ID: <1989Sep30.122344.12326@ivucsb.sba.ca.us> Date: 30 Sep 89 12:23:44 GMT References: <9238@pyr.gatech.EDU> <7905@microsoft.UUCP> Organization: Disillusioned Graduate Hackers, Santa Barbara, CA Lines: 28 brianw@microsoft.UUCP (Brian Willoughby) writes: ~Sure, why overwork the DSP? Question: how would you know which 16 bits ~make up a sample word? I.e. are there some kind of start bits which ~could be used to signal an interrupt. A good setup would involve ~clearing all the shift register bits to one state, and then shifting in ~until the start bit appears in the MSBit. Whatever polarity the start ~bit is, just clear the shift register to the opposite value and interrupt ~the DSP when a full word is ready. The serial port on the 56000 is completely independent of the ALU, etc (i.e., it is like an on board peripheral). I was talking about using the synchronous serial input. You supply it with a bit clock and a word clock and it automatically does the serial to parallel conversion *and* generates an interrupt when it's ready. Usually, my programs for my board consist of a main loop that does absolutely nothing and an interrupt service routine. The (nano)second I get a sample, the interrupt routine starts executing. My service routine loads the parallel data, operates on it, and then stores it to the serial output buffer. The serial section of the chip then outputs the data when the next word clock comes around, all independent of the *real* DSP hardware on the chip. -- Todd Day | todd@ivucsb.sba.ca.us | ivucsb!todd@anise.acc.com "Ya know, some day these scientists are going to invent something that can outsmart a rabbit" -- Bugs Bunny