Recording wav file Using Arduino

Question

I am bit stuck, how can I make my arduino record into .wav files? The arduino is connected with a microphone, and am using the Arduino ADC. Any ideas? Will I be able to play them back using my pc?

many question cross my head

1- Is this possible using an arduino Uno

2- Is this possile using just a microphone connected to the Arduino ADC

3- if yes how can i get the wav format.

The idea gonna be like this

Ardiuno microphone-->Uno ADC -->arduino (library making wav sound)--> Storing data to a an SD card connected via SPI or maybe (connecting a Raspberry as a storage device)

also another question:

4- Do I need an amplifier due to the act that analog output from the microphone is very weak so the ADC couldn't detect the variation

In another log i had seen that i should connect the microphone to a level shifter.And that cause of the analog output is AC so i have to make the negative wave as 0 (for 10 it ADC) the zero point as 512 and the positive as 1024 (10 bit ADC).(really i'm not sure about this part)

doing some research i got this library "https://github.com/TMRh20/TMRpcm/wiki/Advanced-Features#recording-audio" which is supposed to do the job, I mean making some wav file from the analog input.

So any help would be appreciated Thx in advance,

Salah Laaroussi

Answer 1

Yes, although a bit complex it is very possible to do this via an uno.

The biggest hurdles to overcome is the limited amount of RAM and the clock speed. You will have to setup twin buffers to handle writing to the SD card. Make sure the card has a high enough write speed or the entire program will come to a screeching halt as you will run out of memory.

apc mag has a great article detailing out the circuit and code.

http://apcmag.com/arduino-projects-digital-audio-recorder.htm/

Answer 2

There are many things you haven't prepared yet:

1. output of microphone (assuming you know about electronics: still requires a biasing circuit e.g. a resistor + capacitor).

2. the output of the microphone is still very weak (in the magnitude of mV), which Arduino is incapable of capturing so you need a pre-amplifier

3. the design of the pre-amplifier will also include DC offset which makes the output of the microphone all above 0VDC which is in the range of the Arduino ADC otherwise the arduino will capture only those above 0VDC.