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Miniaturized standalone audio analysis tool with Raspi
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Please be positive and constructive with your questions and comments.

Miniaturized standalone audio analysis tool with Raspi

by moscardo on Thu May 13, 2021 6:56 am

Dear Adafruit Support,

I'm working on a project where I would like to have a portable RaspberryPi Zero W to make some audio analysis (speech detection) via a python script and send result back to a server on the local net.

Project constraints are:
    a. form factor and overall size - everything must stay in a small space in order to be integrated inside an helmet;
    b. weight - Because it is to be integrated into a wearable helmet, the weight of the entire project must be kept low;
    c. power consumption - the project must be portable and have a working autonomy of at least 6 to 8 hours;

Questions I'm facing:

Microprocessor / board

Given the space requirements, I thought of the raspberry Pi Zero W. However:

1. are there other boards that can offer the same or better performance (perhaps a small board with a quad core Cortex A7)?
2. does Adafruit have some linux based embedded system which can make a python script (and external libraries) work?

Michorphone input

I need the Raspberry Pi to get audio from an external lavalier microphone. The microphone come with the classical 3.5mm jack.
The first solution I have come up with is to use an USB audio interface which make also necessary to use some sort of USB-OTG to female USB A like this .

3. Is there some "unified" solution instead of using two different pieces of hardware? maybe some sort of hat I can place on top of the Raspberry Pi Zero?

battery and battery charger / booster

To power the project I thought of using the combination of a PowerBoost 1000 Charger - Rechargeable 5V Lipo USB Boost @ 1A - 1000C and a Lithium Ion Polymer Battery - 3.7v 2500mAh or Lithium Ion Cylindrical Battery - 3.7v 2200mAh.

I do not know if I am oversizing the power supply circuit. I guess to figure that out, you need to empirically measure the current consumption with the design up and running, maybe with something like the USB Voltage Meter with OLED Display

4. What are your though about it? Does it make sense to you?
5. Do you think I should use a particular battery for this?
6. Do you think the PowerBoost 500 Charger can also do the job? or maybe some different kind of booster/charger (I've seen there's a lot of them inside the Adafruit product catalogue)?
7. Is it possible to charge the battery using some sort of induction circuitry like this one or this?

As always thank yo so much for you help and support.

moscardo
 
Posts: 18
Joined: Sun Nov 06, 2016 6:12 am

Re: Miniaturized standalone audio analysis tool with Raspi

by blnkjns on Thu May 13, 2021 8:35 am

Can't you do the task in C(++)? Python kind of inflates power use by a factor 5.
Do you want the overhead of Linux? Is boot time important?
Also think about the network connection. WiFi can be demanding. If it does al detection on board, you might just want to share some agregated data, which could be better off with Bluetooth Low Energy. It also has better reach.
I know the new micro:bit v2 has a built-in microphone, can handle speech recognition and has BLE 5.0 and battery connector. The adafruit nRF52 sense is similar:
https://www.adafruit.com/product/4516
I know it has no lavalier input, but the board is so small, you can put it directly at the mouth position.
Or interface a stand-alone one:
https://www.adafruit.com/product/3492
You can even let the helmet track temperature, shake, heading (compass) altitude and humidity!

blnkjns
 
Posts: 624
Joined: Fri Oct 02, 2020 3:33 am

Re: Miniaturized standalone audio analysis tool with Raspi

by moscardo on Tue May 18, 2021 5:52 am

Thank you @blnkjns for your ideas and valuable insights.

Incidentally, I had also considered using an alternative, miniaturized microphone, but I was thinking more of an electret microphone. Nice to have learned about a technique I didn't know before (pulse density modulation).

At the moment I don't know what the weak points of the project might be, either on the software side or on the power consumption side. That's why I wanted to write here: to gather ideas and suggestions from the community.

What I am less familiar with are the issues:
* battery power (LiPo, Lion, etc...);
* induction charging;

If any of you have any further advice or suggestions it will be greatly appreciated.
thanks

moscardo
 
Posts: 18
Joined: Sun Nov 06, 2016 6:12 am

Please be positive and constructive with your questions and comments.