Adau1467 expand I/O ADC and DAC

Hello Martmarttoo,

I would like to ask a few more questions. 

What kind of microphones are you using? Do you need to use an analog mic and an ADC? Can a digital PDM or I2S MEMS microphone work for your application? 

What are the details of the 1 audio input? What level of signal? Where is it coming from? 

The ADAU1966 is really cost effective because it has 16 channels all in one part. 

Also, what is the sampling rates you plan to use? 

There may be an 8-channel ADC that might work for you. I would have to do some more investigation. 

Dave T

Dear Dave T,

Thank you for your reply!

I had to specify, it's not the cost of he IC's but the development boards. As I work in a research and teaching environment, 2x $750 for the boards for one set takes a lot of the budget.

The microphones used are currently InvenSense ICS-40180, using SparkFun Analog MEMS Microphone Breakout - ICS-40180.

We use them to capture environmental sound.

The line in is just something from an esp32/8266.

Best regards!

Hello Martmarttoo,

I understand. The difficulty is the amount of inputs and outputs you are looking for. You could look at the older but still very capable Sigma200 DSP, The ADAU1442. The evaluation board is not cheap but it has two codecs so it has eight analog inputs and 16 analog outputs. It also has a GPIO expansion board which is handy for teaching how to use GPIO in the DSP.

EVAL-ADAU1442EBZ Analog Devices Inc. | Development Boards, Kits, Programmers | DigiKey

For the interface to the PDM microphones I would look at the ADAU7118. It is easy to use and I designed that eval board to be low cost but I did just check on DigiKey and they want $500 for it! I thought this would come in around $200. I obviously have no say with the prices. 

EVAL-ADAU7118Z Analog Devices Inc. | Development Boards, Kits, Programmers | DigiKey

I may contact you directly since I also do some teaching. There may be some other solutions down the road. 

Dave T

Thank you for your help!

Sorry for my late reply, must have lost a notification.

I understand the production of evaluation boards is small batch, but buying a couple adds up quickly.

The amount of outputs is less important. In the final version are only 1 or 2 channels used, the others are for evaluation purposes, so we can switch them around.

This is the first time I use I2S, but now I did some more reading, I've come to understand that every I2S port contains two channels. So if we swap the mic's for a version with integrated I2S, I can connect up to 8 microphones?

Where did you teach?

Thanks again!

Thank you for your help!

Sorry for my late reply, must have lost a notification.

I understand the production of evaluation boards is small batch, but buying a couple adds up quickly.

The amount of outputs is less important. In the final version are only 1 or 2 channels used, the others are for evaluation purposes, so we can switch them around.

This is the first time I use I2S, but now I did some more reading, I've come to understand that every I2S port contains two channels. So if we swap the mic's for a version with integrated I2S, I can connect up to 8 microphones?

Where did you teach?

Thanks again!