Recommended SigmaDSP Model To Start With

Hello Matthew,

This is a bit of a difficult question to ask because it is rather open ended but it is a good question. The 1701 is a great processor to start with because it is easy to learn the SigmaDSP operation and programming since the I/O is pretty much built in and does not take much to configure. There are not a lot of registers so it is not difficult to setup.

Concepts to understand?...

1) The SigmaDSP , especially the 1701, is deterministic in that it executes the code every sample period and there are no loops or jumps in the program. So it cannot hang up or get lost in an infinite loop. So understanding that the schematic you are putting together is executed fully during one sample period. So at any instant it is one sample it is working on. There are ways to operate on more than one sample period like delay lines etc., but for the most part you are using sums and filters for longer response times.

2) The Fixed point architecture is also important to understand.

3) SigmaStudio is not an emulator, the code is being run in the DSP and SigmaStudio is simply communicating with objects running in the DSP code. SigmaStudio will compile and program the part but does not run the actual code.

The RAM in the 1701 is sufficient for running programs at 48kHz or higher. If you run at a lower sample rate then it might become limiting since there are more clock cycles per sample period so more instructions can be executed. If you are looking to have many delay lines or a long delay line then yes, the memory is limiting.

The ADAU1452 family (We call it the Sigma300) is far superior in performance and memory but the converters are not built in and the other features in the part like the sample rate converters and the SPDIF all make for loads of registers. So the part is a bit more complex to get to know. The evaluation boards do help. These processors are much faster and also can do much more like loops and interrupts so it is a little different from the simple 1701.

The ADAU1467 family (We call the Sigma350), is almost exactly the same as the 1452 but it has a lot more memory and more flexibility with the serial ports and the master control port. There are a few other small differences.

So what are you planning to do with the DSP? This will help in choosing. Things like space and power and complexity can make the decision easier.

This should get the conversation going...

Dave T

Hey Dave,

Thanks for all of that info, that is super helpful! Definitely helped me getting a better idea of what the difference would be in getting started. I think for my eventual product design I would need to use either the 1452 or 1467 in order to get the amount of RAM I would need.

I am definitely familiar with the concept of single cycle code execution, so that is good to know about the SigmaDSP line. I noticed you mentioned there being more registers with the superior models, did you simply mean there would be more to learn because of those or is there another drawback that I might be misunderstanding?

Kind of off topic, but is there an advantage to using the 52 versus the 67 if I still plan on using external RAM? Just curious.

As far as what I plan to use them for, I would like to use it in Audio DSP applications for effects processing. Ideally in a guitar effects circuit application and eventually rack mounted effects as well. The effects (Reverbs, Delays, Choruses etc.) all require a good amount of delay memory space.

Thanks so much for your help!

Hello Matthew,

The 52 vs the 67 will depend on what you plan to use it for I suppose. With what you told me there is a possibility that you may want to use more GPIO for controls. The 52 has a number of GPIO for switches/LEDs etc, and it has 6 AUX ADCs for things like control pots. The GPIO is muxed with other pins often.

The 67 has 88 pins so more GPIO pins are available and there are 8 AUX ADCs. So this may be a tipping factor in your design but maybe not. These two parts are very close and the processing cores are exactly the same.

I don't think you will need the extra serial ports but the pins can also be extra GPIO and that you might use.

So these are things to study.

Dave T

I see, it looks like I will only require the features of the 52, I plan on using an independent microcontroller to access controls, but the AUX ADCs will definitely come in handy for potentiometer controls, so thank you for addressing that!

As far as the SigmaStudio software, is there any difference in the setup/getting started aspect when using a chip like the 52 versus the 1701? Obviously the 1701 is a simpler design so I would imagine it would naturally be easier, but mainly I am wondering if there is anything extra setup or install steps when using the 52?

Thanks!

Hello Matthew,

Sorry for the delay in responding.

Yes, the 1701 is a simpler design from a hardware standpoint and simpler from a SigmaStudio standpoint as well. Way fewer registers and no interfacing to an external ADC and DAC.

Since you have DSP experience and I assume experience in I2S and TDM transmissions then starting with the 1452 would not be too difficult.

When you obtain an eval board and want to begin with a simple starter project then get in touch with me. I have a lot of programs that can serve as good starting points.

Dave T