trinket arrives!

A project log for A Wearable Voice Memo Recorder

This project is intended as an entry for the Trinket Everyday Carry Contest. A trinket based, convenient, wearable voice memo recorder

Rue MohrRue Mohr 01/11/2015 at 08:533 Comments

The trinket arrived! kinda late, muh...

New problem tho, it uses a usb-micro connector. It didn't come with a cable and I don't have one.... more ordering and waiting!

let there be progress tho!

A board corey got working found us a new problem. It seems that most SD cards can stall upwards of 300ms 0.3seconds! during write, even at 8khz sampling this is waaaay too long for the avrs ram to buffer samples. we tried an 8G card, 4G card, and an older 512M card, of them, the 512M card was best, peaking its delays at about 148ms. Not sure how to solve this issue.


John Hamann wrote 01/12/2015 at 04:39 point

I don't know that much about how the audio recording process works, but would an external FRAM ic help with buffering the delay?

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davedarko wrote 01/11/2015 at 09:34 point

you could still use an arduino as a SPI programmer or an FTDI adapter to program it? Good luck with SD cards, I'm sorry I can't help you with that.

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esot.eric wrote 01/11/2015 at 09:23 point

write stalls: I ran into this as well, with my similar and kinda-competing project... It turned out something seemingly unrelated was wrong in my initialization/handling of the SD card... (was it treating an HC card as an SC, or vice-versa? I forget). I think, now, it does that only about once every 2 minutes, which, really, .3sec loss every two minutes is hardly noticeable...

There may be other reasons it's not as-regular a problem on mine as it once was (besides the configuration-fix)... one that comes to mind is that I have a blocking printout to the UART (several bytes at 9600bps... so a sizeable fraction of a second, each second), so maybe the SD Card write delays are somehow happening during this time (certainly not *planned* that way). Also, I'm not using a filesystem, blocks are being written almost always consecutively, not sure if that's relevent...

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