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First impressions and dynamic topologies for the ADAU1452

Question asked by jipihorn on Jun 17, 2014
Latest reply on Nov 6, 2014 by mmmike

Hello,

 

I just get the evaluation board I bought as soon as I discovered the ADAU1452 that seems to be what I've searching for.

I tried to find a kind of "number crushing" DSP with audio input/outputs (with no analog part) that can be driven with a microcontroller. This DSP seems good for that: small number of pins, asrc parts... And the previous parts of the SigmaDSP were, to me, useless because of the incredibly small amount of memory. The ADAU1452 has some more useable amount of memory, even though I don't understand why there is so little memory in the SigmaDSP products.

Anyway, as soon as I took a look at the overall development system, I had the surprise to discover that there is no way to program these DSPs with assembly language, C compiler or whatever. Only a limited set of "Lego" parts are available within a graphical environment.

It is ok for playing a little, but I don't see how it is possible to build something serious with that. I can admit that it can be used by non DSP experts, but these "non DSP experts" expect a little more than a locked system.

I could find the way to modify the parameters of the blocks, which is not very elegant (noting by hand the addresses that the compiler decided to assign is ridiculous, at least setting a user fixed address table for parameters is a minimum), but now how can I make conditional links for example ? Or, more generally, how to make dynamic topologies? I cannot believe that the topology has to be hardcoded once for all. If I want to use this DSP for, say, an active filter, there is no fixed number of stages or kind of filters at startup. The user adds one or more sections, according the needs for each channel. I cannot hard code a fixed number of sections, that's not serious! Especially with so little memory available! Now let's say I have to put a fixed number of sections (because the topology is not modifiable) , how to shortcut the ones that are not used ? I don't want to use the DSP for sections I don't use. What a waste of instructions!

Now, the first thing I tried to do is a standard IIR filter. I saw that FIR is supported, but, to my surprise, there is no IIR block! Is it a joke?

I hope that it will be added soon. FIR is inefficient, especially for low frequency manipulations with high sampling rates.

Speaking about sampling rates, this DSP was intended to be used within a system using a non standard sampling rate (between 128-130kS/s). Much to my surprise, there is no way to set a custom sampling rate, only a small fixed list of values that is even missing some standard ones (88K2 or 176K4) and a 22K value that is, I guess, 22K05.

 

So, my first impression is that there are huge unexpected limitations that are more probably due to bad marketing decisions than real technical ones. There are no serious datasheets, not speaking about good user manuals in pdf, not a wiki that is obsolete and useless like any good wiki. The website is a mess; this chip is not even in the SigmaDSP page list! You have to make a search to find it! I had to put all my personal information to download the only tool that can be used with this chip. As I paid the evaluation board, I was obliged to give them to use the card. I hate this. There is no alternative. Why have I to give personal data for anything? That's insane.

 

The first contact was a big disappointment.

 

Jerome

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