Choose different EQ Presets / Filter with GPIOs

MarkusAD Question

Jul 19, 2012 00:00

Hello,

i want to choose between different EQ Presets / Filter via GPIO Pins.

I have a ADAU1401 and he is connected to a microcontroller via I²C. 6 GPIO Pins are connected directly to the microcontroller. The signal which I want to change is delivered via I²S, input is the GPIO Pin 1 (MP1 - Input Sdata_in1) and output ist the GPIO Pin 6 (MP6 - Sdata_out0).

Is it possible to set a value for the 6 Pins (000000 - 111111 [i don't need so many options]), read that value, look, which preset it stands for and "switch this on" ? I could only find a Toggle button function for going through a list of different presets.

I hope i described my problem good enough. I never did anything before with dsp and filter etc. Would be great if somebody could help me.

Thanks.

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ADIApproved Reply

Jul 19, 2012 00:00

In order to do this, you need to do two basic things:

Create a GPIO-to-Index converter.

Use an index-selectable filter cell for your presets.

GPIO-to-Index converter:

For each GPIO input pin, create the following three cells:

GPIO input

DC source

Multiply

Hook them up like this:

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This takes the 5.23 GPIO input and converts it to a 28.0 integer number. The LSB should be multiplied by 1, the next bit by 2, the next bit by 4, and so on...

You then sum up those inputs to create a single integer index number based on the binary adder for the GPIO inputs.

In my example below, I used 4 bits to create an index value that goes between 0 and 15.

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Now, use this as the input to an index-selectable cell that will act as your EQ. I used the IdxSelectable Indp. Multiple Band Filter. The help document attached explains the use of this cell.

Here is the finished product:

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You can find additional help with GPIO usage here: http://www.analog.com/static/imported-files/application_notes/AN-951.pdf

You can also find example projects using GPIO here: http://wiki.analog.com/resources/tools-software/sigmastudio/tutorials

Brett

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MarkusAD Reply

Jul 20, 2012 00:00

Hello Brett,

thank you very much for your fast and detailed reply. This is exactly what i need. In my case i just use the GPIO Pins 1 & 6 for Audio Input & Output.

But I think there is the problem. The audio input signal is a digital signal over I²S in I²S audio mode. The idxSelectbale MBF needs an analog signal. Is there a way to convert the signal? I could not find anything in the SigmaStudio.

One more question i have is why is the IdxSelectable Indp. Multiple Band Filter limited to 16? (it is enough for my purpose) Just want to know for understanding.

Thank you for your help in this matter.

Markus

25970cb0ce01748ace44e135730614e8.jpg-450x293.jpg

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ADIApproved Reply

Jul 20, 2012 00:00

Hi Markus,

Actually, the way to access digital audio data is not to use the "GPIO Input" and "GPIO Output" cells (GPIO_1 and GPIO_6 in your project). Those cells are only used when GPIO inputs/outputs are digital control signals.

When you use the serial ports, the audio signals appear on the input cells and output cells.

Please see here for documentation:

http://wiki.analog.com/resources/tools-software/sigmastudio/toolbox/io/input

http://wiki.analog.com/resources/tools-software/sigmastudio/toolbox/io/output

(and just for reference, your project should look like this)