Data logging - time recording setup


#1

Hi - I just purchased one of these boards from you today to explore for data logging - we want to record at set intervals - say every 5 minutes for say 2 minutes or similar (adjustable) and have the recordings time stamped. I will want these to run un-attended in the field on a battery, so I will want to turn off everything not necessary - for instance I imagine the Bluetooth is cool for programming? but would not be necessary for my application. I am wondering what the maximum SD card size is that I can use on the board and what codec is used. I need good quality audio so would look to keep at 44.1/16 but mono. I am wondering if there is already some code floating around that does this kind of thing that I could alter and or if people have experience of this kind of deployment. I also wonder what the current draw is when any unnecessary extensions are disabled for long term applications. Thanks in advance.

ps. I bought your card to test as I was not happy with the sound quality of the Teensy audio card


#2

@garthpaine Thanks for your order! The Tympan team is currently attending the ASA convention in Minneapolis, but I can assure you that your order will ship out tomorrow 5/8 at the latest :wink:

Tympan is battery operated, and comes with a 500mAH battery installed. You can, of course upgrade the battery.
The Bluetooth module is not used for programming the board (Teensy3.6), and if you are not using it, it can be turned off.
I am not sure how large an SD card you can use, but I would assume that it is not really an issue, since the Teensy doesn’t need to manage all of the data on a card, it will just be writing or reading from it.
Yesterday, at our session here at ASA, Christopher Smalt presented on ‘An Open Source Noise Dosimeter’ where he modified a Tympan for use as a dosimeter. In his work, he was writing audio files to the SD card on board. His abstract can be found on page 1737 here


The Tympan is capable of sampling at 96kHz, so that should not be a problem. The codec we are using is the Texas Instruments TLV320AIC3206.
There is also a Real Time Clock on the Teensy 3.6, which is available for time stamping your data records.

@chipaudette will be able to point you to code that you can use to repurpose for your needs.


#3

Thanks for the input @biomurph. I have tried the basic recording patch provided for Arduino and the sound quality is good - previously I have tried the Teensy audio board on a standard Teensy and did not find the quality good enough for the field recording, audio logging we want to do. I really appreciate the size of the Tympan and the quality :slight_smile:

I found this code

Which looks to do all I need , and paired with a Tympan would make one of the best field audio loggers around I think. But I would need some assistance to adjust the code for the Tympan. I see there are some pin differences but when I change the interface I just get a lot of errors that I am not well enough versed in the code to repair. @chipaudette - could you let me know if there is there something like this already existing for the Tympan?

Thanks for sharing a great product and for the community support.

Cheers, Garth


#4

Hi Garth,

Sorry for the silence. For some reason I am not getting email notifications, so I never heard about this thread until just now.

To answer some of you questions, I’ve done audio recordings on sd cards that were 2gb up to 32gb. I’ve not tried other sizes. The longest recording that I personally have done was only ~12 minutes, so I don’t know what would happen if you tried to do a continuous multi gb recording. If you try let us know what happens!

As for example code, there’s an SD writing example that comes with the Tympan Arduino library. Look under Examples/02-Utility. Or, on GitHub: https://github.com/Tympan/Tympan_Library/tree/master/examples/02-Utility/StereoAudioToSD_Fast

In this example, it starts writing when the vol knob is turned up past halfway and it stops recording when the vol knob is turned down below halfway. This sketch also lights the LEDs different when it is actively recording or not.

Chip