Pic driven digital audio delay

[mister_e]

PIC24 or DsPIC should do the trick... and maybe 18F...

What you need to do exactly?

From what i feel, there's some dedicated IC to do what's you're after that may reduce the development time and maybe the overall cost.

If my feeling is good, even a 12F would do the job

[skimask]

What you need to do exactly?

I built a spectrum analyzer using a pair of 18F4620's, one each for left and right channels. The problem is, the math involved in doing the FFT for the display takes about 64ms, another 6ms to display it on a graphic LCD, and about another 1ms to do housekeeping (all the while I'm doing the sampling). So, by the time the analyzed audio gets to the display, it's 71+ ms old. Looks a bit goofy being just that far out of sync. Actually, it looks fine if my display and speakers are roughly 25 meters away, I see the display immediately and the sound takes roughly 71ms to get to me .

Right now, I'm using the setup described in post#1:
2 - 16bit ADCs
2 - 16 bit DACs
2 - PIC18F4620 doing 256 point FFT spectrum analyzing math
8 - PIC18F4620s doing circular FIFO type audio data buffering/shifting (2 channels x 4 PICs) interconnected to each other thru a serial link, 1st one in line connected to the ADC, last one in line connected to the DAC.
1 - PIC18F2620 doing master timing duties, keeping all the audio data shifting in sync.

The 4 PICs give me a total of about 14K of ram to do buffering with. 44.1khz, stereo, 16 bit sampled audio data is about 176KB/sec, ~70ms is about 14KB, give or take, that's why I use all this to get what I need. The board is ugly (it's on a solderless breadboard), but it works.

12F? You know of a 12F with 14K in it?

Basically I guess I need a 'bucket brigade' type chip...again, with 14K of SRAM...

[mister_e]

So why not using a dedicated Audio delay IC instead? Some are Home theater dedicated.. but who will know?

Ti do some. A PIC/ad/memory/DA plah plah would be just too bad for that kind of task... more distortion than good results...

If you need only a few Spectrum bands, have a look to TDA7416

Sorry but, you make it much complicated that it should be...and you scrap the possible modern sound quality... wich is already soooo bad

Yeah i'm an audio purist

you could still by an audio delay processor
Lexicon, Alesis, Yamaha, etc etc etc

[skimask]

So why not using a dedicated Audio delay IC instead? Some are Home theater dedicated.. but who will know?

I have to find one first, something in less than a BGA9000 pin package! And this project is just a 'gee-whiz' box that goes in between my mp3 player and the stereo itself. Eventually, I'm going to tie it into a LOAD of leds for the spectrum analyzer instead of the graphic LCD.

Ti do some. A PIC/ad/memory/DA plah plah would be just too bad for that kind of task... more distortion than good results...

As it is, the output sounds pretty good. I don't overload the input...and if anything, I introduce noise rather than distortion (at least not the clipping kind of distortion). My sample rate on the A/D and D/A is 44.2khz (because it's a good round number that the master timing PIC produces), I know higher is better, but that would mean more need for memory in the middle.

[QUOTE}If you need only a few Spectrum bands, have a look to TDA7416[/QUOTE]
I like my 128 band per channel spectrum analyzer!

Sorry but, you make it much complicated that it should be...and you scrap the possible modern sound quality... wich is already soooo bad
Yeah i'm an audio purist

Probably, but if we didn't overcomplicate things, we wouldn't be here!

you could still by an audio delay processor
Lexicon, Alesis, Yamaha, etc etc etc

What I've got right now is fairly compact (about the size of a VCR tape) and runs off a battery pack. An external box is not in my 'Master Plan',

[mister_e]

Let's suggest an oldy but still on the market....TAS3103 could be a great suggestion...

It's the first that spring to mind. Worth to look at something like that.

I don't remind the whole option it provide.. but i remember it cost about 10$ USD in a 39TSSOP package, something even my dog can solder on a board


TI TAS DSPs are usually nice. I used them a lot.

[skimask]

Let's suggest an oldy but still on the market....TAS3103 could be a great suggestion...

It's the first that spring to mind. Worth to look at something like that.

I don't remind the whole option it provide.. but i remember it cost about 10$ USD in a 39TSSOP package, something even my dog can solder on a board


TI TAS DSPs are usually nice. I used them a lot.

I'll check into them. They might be the ticket, as long as there isn't a steep learning curve and a load of programming to figure out. I guess I just want the single chip, everything is already done, type chip.

[mister_e]

They're usually easy to use. If you want to use/set the Biquad filter... it's another story... but doable.

They just need a I2C bus, and few commands... no big deal... this is why i told you that maybe a 12F could be enough..