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I have a bit of a specialized question for you. Recently I got my Pi up and running, and am amazed at what it can pull off. But I want more.

I want to be able to record the output from an accelerometer, which is recording aspects of an impact. To do so I will need a minimum of a 12 bit ADC sampling at 100 kHz. At that speed I figure I will need an external microcontroller to buffer the samples, and then have the Pi read in from the buffer to do all of its fun UI stuff. I am planning on using SPI to let them all chat, but am open to suggestions.

Now the kicker is I can only use DIP packages since I do not have PCB abilities. Could someone suggest a microcontroller and ADC that could handle this? I would prefer if there were no expensive programmers required, gotta love the open source theme with the Pi.

Thanks in advance for the suggestions!

  • If you need 100MHz sampling you are probably looking at something that costs a good bit more than the Raspberry Pi. And as soon as you add the requirement that it is a DIP I think you are searching for something that does not exist. – Craig Sep 24 '13 at 20:23
  • Thanks Craig for the reply, good to know that they dont make something in a DIP package that will do that. – user1003131 Sep 25 '13 at 0:57
  • 100kHz is much different. My comment only applied if you needed MHz – Craig Sep 25 '13 at 19:46
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It looks like a MCP3008 may be exactly what you want. The datasheet claims up to 200 ksps at 5 Volts.

In fact there is a tutorial about using this with a Raspberry Pi.

  • Perfect! Thank you Craig. That is a great starting point. I'll be writing the code in Java or C, but it should be fairly analogous. – user1003131 Sep 26 '13 at 12:44
  • Just note that the MCP3008 is 10 bit resolution and you said you needed a minimum of 12 bits. – Frank Smith Sep 26 '13 at 18:57
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100kHz is very much easier than 100MHz!

You could try an ADC121S021 or an ADS7822

  • Perfect! I suspect I'll need a microcontroller to buffer the output from the ADC as well? I dont think the Pi will be able to keep up if it is running a UI. – user1003131 Sep 25 '13 at 13:01
  • @user1003131, Not sure. If you are using spidev the kernel probably does some buffering for you. You should report back here with your findings. – John La Rooy Sep 26 '13 at 1:44
  • Sounds good, will do! – user1003131 Sep 26 '13 at 12:45
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the lack of pcb abilities can be easily compensated with abundance of pcb fab houses on the internet, that not only manufacture, but also assemble your design for a small price.

other than that, you're out of luck. 12bit (16bit w/padding) @ 100Mhz is about 200MB/sec of data you have to process, the Raspberry Pi will NOT be able to do that no matter how many external microcontrollers you attach to it.

  • I factored in the padding into the 12 bit, but understand where your coming from. I did mean to say 100 kHz, but it is still quite a bit of data. I only need to capture for a 10 second interval if that makes any difference. – user1003131 Sep 25 '13 at 1:01

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