interest check--HTPC receiver kit

[Aristarchus]

If somebody were to offer a kit to build a nice HTPC receiver, (assemble it yourself) would anybody be interested? I'm starting on a reference design for Analog Devices' Blackfin line of DSPs, and am kicking around the idea of using that processor as the brains of a simple-yet-high-quality audio receiver. It would end up being less sophisticated than most commercial receivers, but avoid making compromises in the power amplifier section just to cut costs. Seeing as how most sound cards have all the effects processing on board that anybody could ever really want, I see no reason to buy a commercial unit that implements it all over again.

Anyhow, it's a project that I felt like doing for myself, and was wondering if it would be worthwhile to document my efforts for others' use & adaptation.

 

[xonik]

Oh yes, this is something that I think a lot of people (like me) would take interest in. Are you at a point where you can share the general plan you have envisioned?

 

[lamarth]

Put me down as interested, too. I'm a noob though as far as HTPC building goes, so I'd like to know more about how this could benefit me/us in building a HTPC system.

 

[xonik]

Oh, and can you define the scope of such a receiver? Is it strictly for audio, or also video? Will there be resampling/post-processing/converting of audio/video? How about audio/video switching functions? Headphone amplifier? Front-panel display? On-screen display?

By the way, I'd like to offer help if you would like some.

 

[gee]

I've designed, programmed (C/ASM) and production-readied a few boards now which use ADI DSP's, and I've got the Blackfin/SHARC VisualDSP++ tools and a HPUSB-ICE at my disposal.

If you need any help, just ask.

 

[Aristarchus]

I've designed, programmed (C/ASM) and production-readied a few boards now which use ADI DSP's, and I've got the Blackfin/SHARC VisualDSP++ tools and a HPUSB-ICE at my disposal.

If you need any help, just ask.

Nice... I think Iv'e got the hardware end covered, as I've got at least an entire drawer full of ADI dev tools. At one point, I even had 3 BF537 EZ-LITES on mydesk. (too bad they were the crappy old silicon rev though...)

I might tap into your software development expereience though, as I'm pretty much new to the ADI game. Essentially, what I'm working on is a set of modular reference designs for the Blackfin. I'm starting off working on a board that includes RAM, flash, the B-fin and switching regulators, and maybe a PAL or CPLD. The idea is to bring the I/O pins from the Blackfin's ports out to the ednge of the board, so you can more or less cut and paste the peripherals of your choice into a design... Add an ADC and and LCD screen, and you've got a spectrum analyzer. Replace the LCD with a DAC, and you've got an analog signal processor, that you could adapt for either an audio mixing console or a rocket guidance system... Or for that matter, an HTPC receiver My goal at first is to try to make the Blackfin approachable to the common man, by avoiding BGA packages & such.

Anyhow, I'm ramblling. I'm just getting started at this point, Looking at the STAMP board and trying to figure out what I can leave out to make the base module more generalized. As far as what would be included in the HTPC kit, the only limit is the bandwidth of the processor. I'm not sure how much decoding/post processing could be done, as the B-fin is a fixed-point DSP. Still fast though, so it shows promise. As far as features are concerned, you could pretty much add whatever you want....

BTW gee, where do you work? If you're developing professionally with ADI, we need to talk PM me when you get the chance...

 

[gee]

Sounds like you're describing a Cambridge DSP stamp - http://www.camsig.co.uk/products.htm

Here's my thoughts on how to make a dirt cheap Blackfin-based receiver core.

- 4 layer PCB.
- Power supply inputs: 3.3V digital, 5V analog.
- ADSP-BF532 in LQFP. Use a cheap LDO for Vcore, since on-the-fly voltage selection and good efficiency isn't a requirement.
- No SDRAM.
- SPI flash for code storage.
- CS42448 CODEC chip for 6 analog inputs, 8 analog outputs. Connected via TDM to a Blackfin SPORT, configured via SPI or I2S.
- CS8416 for digital input receiption, feeding an AD1895 SRC which drives the aux input on the 42448. Allows up to 6 SPDIF/Toslink inputs. SPI or I2S configuration.
- 24.576MHz oscillator clocking the DSP PLL and all audio hardware. Do all audio processing at 96KHz.
- RS232 interface to a controller. Could be the host PC directly, or a separate control board which includes a LCD and a PIC/AVR/whatnot.

- Simple software architecture, kicked off by the SPORT ISR. Each output channel is a mixture of any of the input channels, fed through an array of connectable 31-bit fixed point biquads which form high/low/bandpass filters, parametric equalizers and whatever else. Main thread handles communication with the controller.

- Analog outputs... use an array of gainclones