Recording sound times and porting them to a computer.

[hobbyingNow]

Hello all!

Disclaimer: My microcontroller knowledge is based off of a couple courses I took in college so anything that I write here could be absolutely wrong.

So a general overview of what I would like to do is record beeps and along with those beeps record a precise time of when the beep happened. How I was envisioning doing this was have a microcontroller with some memory, a microphone and a ban pass filter on it and through that put my audio onto the circuit memory. Then I would like to transfer the audio with times from the circuit memory to my computer into a file of some sort so that I can use it in a program I've made.

I don't even know where to start other then I know that the microcontroller I used in college was a PIC. I was hope I could get some specific parts that would be good to use on this project. Also if anyone has any advice or a better design or has questions please let me know.

Thanks,
-Josh

 

[mdanh2002]

You can build a simple recording device from a PIC. Use an electric condenser microphone (ECM) with the correct preamp (can be built from a few transistors, resistors and capacitors) to get the output voltage within 0-5V. Then feed it into the PIC's analog-to-digital converter (ADC) unit, which will convert the voltage (0-5V) to a byte value (0-255). You can then transmit the bytes to the computer serial port via the PIC UART unit. A simple software running on the PC (something like Hyperterminal) will save those bytes into a file.

If the PIC has some storage capability such as external EEPROM or SD-card, you can also save the data without needing for a PC client.

Given the PIC and the serial speed, you can probably record at 8bit, 8kHz sampling rate. The analysis of when the beep happens will probably have to be done on the computer side, as the PIC is nowhere fast enough for audio recording and processing at the same time.

 

[Mr RB]

Trying to record people's PIN numbers??

 

[misterT]

Trying to record people's PIN numbers??

ATM machines or card readers don't use different tones for button presses. Just one tone to give user feedback.

 

[Mr RB]

Good point!

Maybe I'm too suspicious lately, there's been plenty of news reports of crims recording PINs and key data from public library computers and internet cafes, or attaching devices to cash machines etc.