DAC talk: FPGA vs DSP?

Are you an idiot? You realize that ASICs are significantly more efficient, are significantly smaller, and consume less power.

You use FPGAs if you don't want to incur NRE, you are trying to reduce development time, you need field programmability, or you want a marketing sound bite.

 

Not true. There are many reasons to use an FPGA.

• You aren't manufacturing at volume so the cost of developing custom silicon and building a manufacturing process is prohibitive
• You need field programmability for your particular application, for instance, you need to implement specific features post launch
• You're in prototyping and need to spin up revisions quickly
• A small penalty in size, power consumption, and efficiency is acceptable

In general, FPGAs have steadily followed Moore's law making them more attractive over time. That doesn't necessarily make them the best solution for an audio implementation, but I understand why some companies would use them.

 

Sure.

As an aside, I'd suggest finishing your high school basic electronics class or at least research more on Wikipedia before trying to opine on here about the relative merits of different ICs.

 

bwhaha, after reading your post, felib, I realized the original post said DSP vs FPGA.

DSPs = simpler, more efficient for signal processing. they can also be a good choice if you don't need the performance of an FPGA.

Once you move to bonkers sampling rates, DSPs fall apart and cost per unit goes up.

 

DSPs are processors, with special DSP purpose HW. An FPGA is more like configurable HW.

FPGAs do concurrent "operations". Programming FPGAs requires knowledge of programming languages similar to those used to develop ASICs (VHDL and Verilog). DSPs still need to execute instructions one or a few at a time. Programming FPGAs requires knowledge of typical processor programming languages such as C or C++ (along with the processor's own Assembly language).

To program an FPGA one usually requires a HW/Design Engineer. For a DSP one usually require a SW/Embedded Engineer.

In general:
1) FPGAs tend to be much faster.
2) FPGAs tend to be more expensive, and may require more power than DSPs

One can put a processor core in an FPGA, but typically those are general purpose processor cores.

I would probably go for a DSP if I want cheaper and less power consumption, and all things required can be acomplished by the DSP. If I cannot acomplish certain critical things with a DSP, then I would go for an FPGA.

If I'm not going to change HW, and I have shit loads of volume, then I would go from an FPGA to an ASIC, since volume can drive ASIC cost way down (per part), and power/size can be significantly lower.

All those PCM whatever DAC chips from TI, or AKM parts and so forth, are ASICs. They tend to be cheaper and much more efficient than DSPs and FPGAs... because of volume.

IMO, the cheap, efficient, and in some ways desirable way to design, say a DAC end product, is to get an ASIC from TI, AKM, ESS or whatever. If you want to do something that those ASICs do not support, then I would consider a DSP. If the DSP does not cut it (and that would be surprising), then I would go for an FPGA. To me it is hard to justify an FPGA in most audio designs though. But then you do have folks like Chord that has these crazy fast ultrasonic filters. Go figure.

 

BTW, I just looked at the Lattice ECP3-150 thingy the OP alludes to. Thats 149k LUTs (149 LUTs is basically nothing, to the point that one can't do shit with it).

The claimed 0.5 W power consumption is a starting point. Once you put shit on the FPGA, power is going to go up.

Lattice specs:

• Up to 16 channels at 3.125 Gbps
• 800 MBps DDR3, 1Gbps LVDS.
• Up to 586 programmable sysIO buffers with support for PCI Express, Ethernet (GbE, XAUI, & SGMII), HDMI, SMPTE, Serial Rapid I/O, CPRI and JESD204A/B and more.
• Up to 150 k LUTs and 6.8 Mbits of SRAM.
• Wide array of packages as small as 10.0 mm x 10.0 mm with power consumption below 0.5 W.

And you need all that for an audio application, because?

All that power is not likely gonna come out for free.

Price -
Lattice ECP3-150: $400 - $610 (http://www.latticestore.com/searchresults/tabid/463/searchid/1/default.aspx?searchvalue=lfe3*)
ADSP-SC589: $17 (http://electronicdesign.com/micropr...porates-cortex-a5-connected-signal-processing)

With the given specs power consumption for the Lattice is probably going to be way higher than the ADSP chip.

So why the OP feels the Lattice part is "certainly better than high level DSPs" is beyond me.

Not only that, the FPGA market is mainly dominated by Xilinx and Altera. I would be concerned about tool maturity and support. Xilinx, big as it is, had some mayor issues when they switched to the Vivado design suite. I dunno how stable and well supported Lattice parts are.

 

Michelle Wie wears tight clothes and is very very cute. Like FPGAs, she proly consumes a lot of power and is pricy.

 

U guys are assholes. I like.