It seems very basic but I am new designing these parts.
When you say turning the part on and off, do you mean fully powering down and powering up the ADAU1761? Or do you want to temporarily mute the audio?
Powering the part down and up is not quite as simple as just pressing a button, if you want to fully remove power to the 1761. The issue is that when you turn it back on after cutting the power, you will need to reload all of the register settings to the 1761. Take a look at page 24 of the datasheet for the startup sequence for more information about what this would mean.
If your goal is to temporarily mute audio coming from the 1761, then return it when the button is released, you have a few options. If you're using an external microcontroller, you could set it to make an I2C or SPI write to the 1761 to mute your desired output. Otherwise, there are some potential workarounds you could try involving the JACKDET pin or one of the ADCs, but those have tradeoffs of their own.
Let me know a little more about your application and what you mean by turning it off and on, and I will help you narrow down the best solution.
since this is a battery powered device, I dont want the product to drain
the batteries when not in use.
I appreciate any comments
Do you have a controller in the design?
You can stop the DSP, you can stop clocks going to several different sections of the part and you can stop the clock generators themselves. All will lower power but it would require an external controller. It cannot shut itself down.
no controller is in the design now
the project is pretty straight forward. It is hearing protection (think
those big ear muffs) , that have microphones on the outside and speakers
inside. User can adjust the volume level he hears. SOund is picked up
with analog mic, filtered, and then compressed when volume level to the
internal speakers exceeds a certain level. SO if working in a loud
environment, I can still hear you but if a big clang or bang goes off,
my hearing is protected.
It is battery powered, as typical use is maybe 2 hours at a time, maybe
once or twice a month, maybe 2 or 3 months between uses.
The Adau1761 does not have a self boot mode. You need a microcontroller to handle loading code into the DSP.
Thanks for the extra clarification. Sometimes I am too busy with other thoughts and I miss the obvious.
So if this is your project then the ADAU1772 is the part you need to look into. It is low power and is designed to be used in a headset under battery power. It has a limiter, a PGA for each of four analog inputs, headphone output, and low latency. It has a very limited "DSP" which is designed for calculating 32 bi-quad filters quickly. There is also a new part that will be out soon that is a wafer level part and with even lower latency.
The ADAU1772 will boot up on its own using an external EEPROM. It has some GPIO pins that can be used for things like up/down volume, mute, bypass, or a different filter configuration.
So you could realize your product with very few external components.
I looked at his part too and have its eval board. do you think there
is a way to use an adc for analog volume control?
I think there may be a creative way to do this. You can bring an external ADC data into the core using the serial port. So that is easy. Unfortunately this part does not have en externally controlled volume control. What I mean by external is where there is a pin on the GUI for a gain input that sets the gain of the volume control. The other way to do it is to use a multiply block to multiply the audio with an external ADC signal but again, there is not 2-input multiple in this part.
However! there are four limiters in this part and there is a GUI for these that bring out the input to the sidechain signal path. Then the limiter can be setup to function as a gain control. The software team has actually been working on this limiter cell to improve its functionality and also to make it work as a zipper-less volume control. So let me digest some of their work and see if this would work for you. It is not available yet but will be soon.
Feel free to remind me if you do not hear back in a reasonable time.
that would be great
But if I am correct, all the configuation regisers have to be loaded
from the outside on power up. I interpret this a it must have an
outside microprocessor to load the registers, Am I wrong ?
No, you do not need an external MCU. This part can self-boot from an external EEPROM. It will load in the program and all register settings. Any external ADC will have to be configured somehow. This part is not able to configure another part.
is there a way to use EVAl1761 board in untethered from PC operation?
(stand alone, battery powered)
No, the ADAU1761 requires a controller to boot it up if you are not using SigmaStudio. This part is not capable of booting itself.
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