Re: Maximum iPhone sample rate
Re: Maximum iPhone sample rate
- Subject: Re: Maximum iPhone sample rate
- From: Alex Wiltschko <email@hidden>
- Date: Tue, 11 May 2010 10:30:35 -0400
>From some preliminary digging around, it seems that I'd be able to pass data over digital pins. I'm not 100% sure, and I also don't know whether the baud rate over the pins would exceed 48K, but hopefully I'll be a member of the program soon and all will be revealed.
re: logic sniffer, I'm trying to make a general-function, super-portable oscilloscope that's easy to set up and use. Rather, I've already done that for audio inputs, but I'd like to extend it to applications which require higher-throughput and/or DC coupled signals. Although powerful, the Dangerous Prototypes products aren't as portable (require a laptop) and definitely aren't as easy to use and interact with as the iPhone.
William: I couldn't find it listed anywhere. Under "Audio Playback" in the iPhone tech specs (
http://www.apple.com/iphone/specs.html), the playback frequency response is listed as 20 - 20,000 Hz, but nothing is listed for the microphone or line input.
For now, I'll have to be satisfied with 48K sampling. If you're interested, the app's called "oScope" on the app store.
Alex
On Mon, May 10, 2010 at 9:48 PM, Brian Willoughby
<email@hidden> wrote:
I suppose it may be obvious that I'm not signed on to the "Made for iPhone" program. I have no idea whether the digital pins are accessible in an arbitrary programmed manner. All pins may have defined functions already, so it may not just be that you aren't allowed, but it may not even be possible.
If you just want digital inputs, then the Openbench Logic Sniffer is already functional and is shipping. It's only the analog inputs that are still being designed.
I believe the OLS supports 200 MHz sampling on 32 inputs. Since you're only interested in 100 kHz, you might try the Dangerous Prototypes "Bus Pirate" which you could even write new firmware for, if you need different features.
Brian
On May 10, 2010, at 18:34, Alex Wiltschko wrote:
The idea would be to use the digital pins, not the audio pins on the dock. That way I'd be able to bypass any filtering the built-in DSP chip is doing. I'm talking with some hardware folks about that possibility.
Very cool tip on Dangerous Prototypes, that's exactly the kind of thing I'm looking for! Thanks,
Alex
On May 10, 2010, at 9:23 PM, Brian Willoughby wrote:
The sample rate is limited by the iPod/iPhone/iPad hardware. Joining the "Made for iP*" program won't change the hardware. You could attach external hardware, but by the time you attach external hardware, you might as well be using a real Mac as a host. If you're going to design an accessory, then the iPhone is probably not the correct host platform for your desired features.
If you want to do 100 kHz sampling with DC coupling for electronic circuit troubleshooting, then you should look into Dangerous Prototypes. They have an Openbench Logic Sniffer project that is shipping and a Digital Sampling Oscilloscope project that is in the design phase. These are USB devices which can plug in to any USB host.
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