Pic driven digital audio delay

[skimask]

Got an audio project...quick description:
Using 8 PIC18F2620's, 4 per channel, 2 channels, running @ 40mhz
Twin 16bit ADC's on the left/right inputs, sampling @ 44.1khz.
Twin 16bit DAC's on the left/right outputs, 44.1khz rate.

One master PIC sending out pulses at 44.1khz (actually 44.247khz, TMR0 overflow driven)...1st PIC in line samples reads ADC, stores audio, shifts it down the line until the last PIC, last PIC in line sends out 16bit audio to DAC.

Each of these PICs, except for the master timing PIC, is basically a 3.5K FIFO buffer providing a total delay of about 66.6ms.

This is all mounted on a spectrum analyzer and neccessary because it takes the spectrum analyzer PIC that amount of time to process the audio data. And using this digital audio delay keeps it all in sync.

Any easier way to do this, short using a single PIC and an external ram chip (or a PIC with a load of ram, I can wish for it).

[ronsimpson]

Think about DSPs or ARM or FPGA.
DSP are built to do this job.
An ARM processor is much faster and has large amounts of RAM.
With an FPGA I have done this with video not audio.

[skimask]

Think about DSPs or ARM or FPGA.
DSP are built to do this job.
An ARM processor is much faster and has large amounts of RAM.
With an FPGA I have done this with video not audio.

Sure would...I'd prefer to stay with PICs. ARMs, FPGAs mean more programmers, software, tools, etc. to buy. Not that it's a bad thing! I've been meaning to get into FPGA/Programmable logic/etc, don't really know where to start, or even if they're for me (meaning do I really need them?).

[ronsimpson]

Altera has free software for their FPGA. It will open up a new world to you.

http://www.hbbrbasic.com here is a BASIC compiler for ARMs. You almost have to use LPC2000 type of ARMs or AT91SAM7. The price is right! You will get 50MIPs and RAM! 10X speed!

I do not know of DSP-BASIC. DSP is the right choice.

[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...