Thanks for the response! I'll be recording uncompressed and saving as a WAV file. The audio files will be used in video editing so uncompressed is preferred, and avoiding licensing fees is always good. Yeah, I misread the stuff about the card size limits. From their user guide= : *This driver supports the following cards (operating at the standard +3.3V):-* ** All standard SD cards (up to 4GB which is the maximum possible)* ** All standard SDHC cards* ** All standard MMC cards* ** All standard MMC Plus cards* Reverse FAT32 driver? I don't suppose there is one already out there? The codec IC I may be using is the Nuvoton NAU8822L. I only have experience with PIC microcontrollers so that's what I will be selecting from, 18F or 24F families. Package size, power usage, amount of RAM for a sufficient buffer, and required peripherals will be considered. Size is my biggest concern. There are tons of digital audio recorders out there, but the small ones (really small ones) don't have the features needed for my purposes. And the recorders that do, such as the Zoom H1, are too big. Even small personal recorders such as those from Sony or Olympus are just a touch too big. -- Sincerely, James Burkart *Filmmaker & Documentarian* *Burkart Studios* 415.738.2071 | Phone 925.226.4910 | Fax *Web:* burkartstudios.com *Facebook:* facebook.com/burkartstudios On Thu, May 12, 2016 at 3:13 AM, James Cameron wrote: > On Thu, May 12, 2016 at 02:31:30AM -0600, James Burkart wrote: > > I aspire to make a small audio recorder. I need to decide how and on > > what it will record on, and how I will retrieve the files. > > > > I was originally considering having it record to microSD. Initial > > obstacles I found were speed limitations from using SPI, and the > > FAT32 drivers I was looking into will only access up to 4GB. > > > > FAT Driver I am reading up on. > > * > http://www.embedded-code.com/source-code/memory/secure-digital-mmc-memory= -cards/secure-digital-mmc-memory-card-fat16-fat32-driver > > < > http://www.embedded-code.com/source-code/memory/secure-digital-mmc-memory= -cards/secure-digital-mmc-memory-card-fat16-fat32-driver > >* > > I've not used this code, but I have used some of the Arduino SD > libraries, as well as the one in Open Firmware. (I've also dabbled > last year in Linux kernel audio drivers for codec chips.) > > I'm surprised at a 4GB card size limit, but a 4GB file size limit is > inherent in the FAT format. You can work around that by opening a new > file. At your fastest bit rate, no compression, you'll need one every > 4.14 hours. > > > Alternatively I was considering having the recorder write to flash > > memory and then retrieving the files via USB interface. I know next > > to nothing about attempting this method. Immediate obstacles for me > > would be figuring out the whole USB thing, and finding/writing FAT32 > > drivers for use with the flash memory (or do I?). > > Correct, you won't need FAT32 media drivers if you aren't exposing the > Flash > directly to USB on a block by block basis. But if you want to use USB > storage class, you'll need a reverse FAT32 driver to map the I/O > requests to Flash blocks. > > > USB stuff I have found. > > *http://www.signal11.us/oss/m-stack >* > > > > I would appreciate any thoughts or input, suggestions, sources to read, > > what to consider, etc... > > What questions should I be asking myself? > > 1. which processor to use? > > 2. which audio codec chip to use? > > 3. if using a codec, how to clock the i2s stream into your core. > > Suggested sources: > > https://www.pjrc.com/store/teensy3_audio.html (codec daughter board > for an ARM board), > > http://www.pjrc.com/teensy/td_libs_Audio.html > > https://www.arduino.cc/en/Reference/SD > > https://www.adafruit.com/products/1381 (buy an interface module rather > than make it yourself, then hook it up to your micro of choice) > > > Note: I would like to be able to record stereo 48kHz/24-bit but I will > > settle on mono 44.1kHz/16-bit. > > With or without audio data compression? (mp3, ogg) > > For what it is worth, I was preparing to embark on a similar project > and decided it was better to buy a pre-made purpose-built device. > > https://www.zoom.co.jp/ was where I went for them, got an H4n field > recorder, which I use for wildlife, and sound system integration (XLR > yay), and an H1 for lectures and sermons, since gifted. > > > James Burkart > > -- > James Cameron > http://quozl.netrek.org/ > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .