5 ms·

80 FFTs Per Second To Detect Whistles and Switch On Lights

156 points by Lightning 13y ago

bbq 13y ago
Great execution on every level. Incredible work.
dan1234 13y ago
Does anyone know how much power this would use while waiting for commands, considering it really needs to be running 24/7?
- simcop2387 13y ago
  Looking at the hardware he's got there, 10-15 mW max.
- notimetorelax 13y ago
  Not much I'd think. It is based on a microcontroller [1] that runs on 50MHz frequency. If my calculations are right then maximum consumption for it is 0.0486 Watt. [1] http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=K10_50&webpageId=132639102321170846DD8B&nodeId=01624698C9DE2DDD8B&fromPage=tax http://www.freescale.com/webapp/sps/site/prod_summary.jsp?co...
- drostie 13y ago
  Assuming that the FFTs handle independent slices of data (as I can't see why you'd go back to the time domain), the data throughput they're handling is 2048 * 15 bits * 80 Hz = 2.5 Mbps. That may sound like a lot, but it's not unprecedented and it does not require huge power consumption; think of a USB connection hub or perhaps an ethernet hub. Actually the thermodynamic requirements of that sort of computation are much much less than the practical requirements; at room temperature the minimum power to handle that bandwidth is only 3 × 10^-15 watts; the FFT doesn't need to add to that because the FFT is a reversible computation. We're a long way away from perfection in this sense.
- Retric 13y ago
  Not much, I have seen similar projects powered by leaching energy from radio waves.
- swamp40 13y ago
  It has a plug for a wallbrick, and I don't think the author optimized his hardware or code for ultra-low power - ie small batteries. (Running 80 FFT's every second isn't going to be great on batteries.) The Kinetis K10 he used WOULD BE an excellent processor choice for an ultra-low power design, though. You could have a low-power comparator monitor for noises and only wake the processor up when it heard something interesting. With some simple tricks like that, you could probably run for months on a couple AA batteries.
  - stephencanon 13y ago
    > Running 80 FFT's every second isn't going to be great on batteries. Assume for the moment that floating-point were used instead of fixed-point: A 2048-element real-to-real FFT requires a bit less than 40Kflop, or 3.2Mflop/sec to get 80FFT/sec. Modern hardware is capable of > 1Gflop/joule, so the raw compute of 3.2Mflop/sec actually takes something on the order of 3.2mw. Of course, the computation is being done in q15 instead of float, which (in theory) should require something on the order of 1/2 the energy. On the other hand, the processor can’t just do FFTs. It’s spending energy going in and out of lower-power states, running other code, etc, etc, and I don’t have any data for the energy usage of the M4 specifically, to say nothing of the other components on the board. In principle though, the energy actually consumed by performing the FFTs should be pretty minimal; most of it will be going to everything else unless the hardware and software are both very carefully designed for efficiency.
femto 13y ago
It'd be fun to put this beside a bird cage, and see if the bird could learn to control its environment. If so, I imagine quite a number of doting bird owners would be prepared to pay money to give their pet "the gift of independence".
- rurounijones 13y ago
  That is a frankly brilliant idea which I never would have thought of. Probably very doable with smart birds like (but not limited to so, don't hate me) parrots. On the other hand, some of those bird species can be quite mischievous, be very careful before giving it control over your house.
annon2003 13y ago
You can also whistle to your android i.e. to wake up a Siri like assistant: https://play.google.com/store/apps/details?id=com.pannous.voice.actions.free https://play.google.com/store/apps/details?id=com.pannous.vo...
deleted 13y ago
[deleted]
MichaelApproved 13y ago
This feels like The Clapper of the 21st century. That product is still bought and in the pop culture. Good luck to the developer. http://www.youtube.com/watch?v=cfgN5tUgjb8 http://www.youtube.com/watch?v=cfgN5tUgjb8
jwr 13y ago
The ARM Cortex M4 is quite an amazing core, actually. The DSP instruction set is beautiful in its simplicity, and the best part is the table with clock cycles per instruction ("1" in all rows). On a related note, I wonder — the OP used a Freescale Kinetis microcontroller, those begin at around $2.50 at Farnell. Meanwhile, Texas Instruments still hasn't began distributing their Tiva (formerly Stellaris) chips, with the M4F core. I wonder when they'll finally get around to it, and whether the pricing will be competitive with Kinetis.
RBerenguel 13y ago
Reminds me of an IBM DeveloperWorks (IIRC) script to control your computer by whistling (I wrote about it in my blog many years ago and used it for a while, it was fun :)
mjb 13y ago
That's a really cool project. On one hand, I feel like it's wasteful to do stuff like this digitally, with FFTs, rather than with analog filters. That's a whole lot of transistors to do something that could be done with vastly fewer with an analog approach. On the other hand, the digital approach is more flexible, almost certainly lower power, and not much more expensive. The rise of tiny chips that are great at DSP, partially driven by mobile tech, is really exciting. It'll be great to see what it's going to lead to in future.
- droz 13y ago
  Sadly, analog design seems to be becoming a lost art.
  - swamp40 13y ago
    Agree. As a hardware design engineer, I can't say I miss it too much though. Run the signal right into a DSP and call it a day. Doesn't work right? Must be a firmware problem.
joelcollinsdc 13y ago
What courses/topics does one need to learn to be able to create this kind of hardware themselves?
- stonemetal 13y ago
  Depends on if you mean off the shelf chips or not. If not then I would expect a second or third year EE student to be able to pull it off. It is way to simple for an EE undergrad senior project. If you mean design and fabricate the chips then that is a bit more.
  - alexchamberlain 13y ago
    The main thing I struggle with is the confidence to actually manufacture something; I can sketch a schematic, but I've never produced a PCB.
    - femto 13y ago
      It's educational and confidence building to DIY for a simple circuit. Try a board with all "though hole" components first. Start with a simple schematic, maybe a 555 timer flashing an LED[1]? Grab a PCB layout program, such as gEDA/PCB [2], Eagle [3] or an old version of Protel. You can even use an everyday drawing package, such as Inkscape for really simple boards, if you think a CAD package is too complex. Alternatively, use a resist pen [7] to draw the circuit directly on your blank PCB. Buy a PCB making kit, which includes a blank piece of PCB, chemicals and instructions [4]. Follow the instructions [5]. Solder the components on [6]. Turn on the power! [1] http://www.instructables.com/id/Flashing-LED-using-555-Timer/ http://www.instructables.com/id/Flashing-LED-using-555-Timer... [2] http://pcb.geda-project.org/ http://pcb.geda-project.org/ [3] http://www.cadsoftusa.com/eagle-pcb-design-software/ http://www.cadsoftusa.com/eagle-pcb-design-software/ [4] http://www.jaycar.com.au/productView.asp?ID=HG9990 http://www.jaycar.com.au/productView.asp?ID=HG9990 [5] http://www.jaycar.com.au/images_uploaded/pcboards.pdf http://www.jaycar.com.au/images_uploaded/pcboards.pdf [6] http://www.staff.vu.edu.au/sokolov/library/datasheets/solderng.pdf http://www.staff.vu.edu.au/sokolov/library/datasheets/solder... [7] http://www.jaycar.com.au/productView.asp?ID=TM3000 http://www.jaycar.com.au/productView.asp?ID=TM3000 --- Edit: add resist pen suggestion
Shivetya 13y ago
Eight paragraph of this article, http://www.washingtonpost.com/wp-dyn/content/article/2007/02/16/AR2007021602102.html http://www.washingtonpost.com/wp-dyn/content/article/2007/02... sounds like a forerunner
snake_plissken 13y ago
i can't whistle! :'[

156 points by Lightning 13y ago

bbq 13y ago

Great execution on every level. Incredible work.

Does anyone know how much power this would use while waiting for commands, considering it really needs to be running 24/7?

simcop2387 13y ago
Looking at the hardware he's got there, 10-15 mW max.
notimetorelax 13y ago
Not much I'd think. It is based on a microcontroller [1] that runs on 50MHz frequency. If my calculations are right then maximum consumption for it is 0.0486 Watt. [1] http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=K10_50&webpageId=132639102321170846DD8B&nodeId=01624698C9DE2DDD8B&fromPage=tax http://www.freescale.com/webapp/sps/site/prod_summary.jsp?co...
drostie 13y ago
Assuming that the FFTs handle independent slices of data (as I can't see why you'd go back to the time domain), the data throughput they're handling is 2048 * 15 bits * 80 Hz = 2.5 Mbps. That may sound like a lot, but it's not unprecedented and it does not require huge power consumption; think of a USB connection hub or perhaps an ethernet hub. Actually the thermodynamic requirements of that sort of computation are much much less than the practical requirements; at room temperature the minimum power to handle that bandwidth is only 3 × 10^-15 watts; the FFT doesn't need to add to that because the FFT is a reversible computation. We're a long way away from perfection in this sense.
Retric 13y ago
Not much, I have seen similar projects powered by leaching energy from radio waves.
swamp40 13y ago
It has a plug for a wallbrick, and I don't think the author optimized his hardware or code for ultra-low power - ie small batteries. (Running 80 FFT's every second isn't going to be great on batteries.) The Kinetis K10 he used WOULD BE an excellent processor choice for an ultra-low power design, though. You could have a low-power comparator monitor for noises and only wake the processor up when it heard something interesting. With some simple tricks like that, you could probably run for months on a couple AA batteries.
- stephencanon 13y ago
  > Running 80 FFT's every second isn't going to be great on batteries. Assume for the moment that floating-point were used instead of fixed-point: A 2048-element real-to-real FFT requires a bit less than 40Kflop, or 3.2Mflop/sec to get 80FFT/sec. Modern hardware is capable of > 1Gflop/joule, so the raw compute of 3.2Mflop/sec actually takes something on the order of 3.2mw. Of course, the computation is being done in q15 instead of float, which (in theory) should require something on the order of 1/2 the energy. On the other hand, the processor can’t just do FFTs. It’s spending energy going in and out of lower-power states, running other code, etc, etc, and I don’t have any data for the energy usage of the M4 specifically, to say nothing of the other components on the board. In principle though, the energy actually consumed by performing the FFTs should be pretty minimal; most of it will be going to everything else unless the hardware and software are both very carefully designed for efficiency.

femto 13y ago

It'd be fun to put this beside a bird cage, and see if the bird could learn to control its environment. If so, I imagine quite a number of doting bird owners would be prepared to pay money to give their pet "the gift of independence".

rurounijones 13y ago
That is a frankly brilliant idea which I never would have thought of. Probably very doable with smart birds like (but not limited to so, don't hate me) parrots. On the other hand, some of those bird species can be quite mischievous, be very careful before giving it control over your house.

annon2003 13y ago

You can also whistle to your android i.e. to wake up a Siri like assistant: https://play.google.com/store/apps/details?id=com.pannous.voice.actions.free https://play.google.com/store/apps/details?id=com.pannous.vo...

deleted 13y ago

[deleted]

MichaelApproved 13y ago

This feels like The Clapper of the 21st century. That product is still bought and in the pop culture. Good luck to the developer. http://www.youtube.com/watch?v=cfgN5tUgjb8 http://www.youtube.com/watch?v=cfgN5tUgjb8

jwr 13y ago

The ARM Cortex M4 is quite an amazing core, actually. The DSP instruction set is beautiful in its simplicity, and the best part is the table with clock cycles per instruction ("1" in all rows). On a related note, I wonder — the OP used a Freescale Kinetis microcontroller, those begin at around $2.50 at Farnell. Meanwhile, Texas Instruments still hasn't began distributing their Tiva (formerly Stellaris) chips, with the M4F core. I wonder when they'll finally get around to it, and whether the pricing will be competitive with Kinetis.

RBerenguel 13y ago

Reminds me of an IBM DeveloperWorks (IIRC) script to control your computer by whistling (I wrote about it in my blog many years ago and used it for a while, it was fun :)

mjb 13y ago

That's a really cool project. On one hand, I feel like it's wasteful to do stuff like this digitally, with FFTs, rather than with analog filters. That's a whole lot of transistors to do something that could be done with vastly fewer with an analog approach. On the other hand, the digital approach is more flexible, almost certainly lower power, and not much more expensive. The rise of tiny chips that are great at DSP, partially driven by mobile tech, is really exciting. It'll be great to see what it's going to lead to in future.

droz 13y ago
Sadly, analog design seems to be becoming a lost art.
- swamp40 13y ago
  Agree. As a hardware design engineer, I can't say I miss it too much though. Run the signal right into a DSP and call it a day. Doesn't work right? Must be a firmware problem.

joelcollinsdc 13y ago

What courses/topics does one need to learn to be able to create this kind of hardware themselves?

stonemetal 13y ago
Depends on if you mean off the shelf chips or not. If not then I would expect a second or third year EE student to be able to pull it off. It is way to simple for an EE undergrad senior project. If you mean design and fabricate the chips then that is a bit more.
- alexchamberlain 13y ago
  The main thing I struggle with is the confidence to actually manufacture something; I can sketch a schematic, but I've never produced a PCB.
  - femto 13y ago
    It's educational and confidence building to DIY for a simple circuit. Try a board with all "though hole" components first. Start with a simple schematic, maybe a 555 timer flashing an LED[1]? Grab a PCB layout program, such as gEDA/PCB [2], Eagle [3] or an old version of Protel. You can even use an everyday drawing package, such as Inkscape for really simple boards, if you think a CAD package is too complex. Alternatively, use a resist pen [7] to draw the circuit directly on your blank PCB. Buy a PCB making kit, which includes a blank piece of PCB, chemicals and instructions [4]. Follow the instructions [5]. Solder the components on [6]. Turn on the power! [1] http://www.instructables.com/id/Flashing-LED-using-555-Timer/ http://www.instructables.com/id/Flashing-LED-using-555-Timer... [2] http://pcb.geda-project.org/ http://pcb.geda-project.org/ [3] http://www.cadsoftusa.com/eagle-pcb-design-software/ http://www.cadsoftusa.com/eagle-pcb-design-software/ [4] http://www.jaycar.com.au/productView.asp?ID=HG9990 http://www.jaycar.com.au/productView.asp?ID=HG9990 [5] http://www.jaycar.com.au/images_uploaded/pcboards.pdf http://www.jaycar.com.au/images_uploaded/pcboards.pdf [6] http://www.staff.vu.edu.au/sokolov/library/datasheets/solderng.pdf http://www.staff.vu.edu.au/sokolov/library/datasheets/solder... [7] http://www.jaycar.com.au/productView.asp?ID=TM3000 http://www.jaycar.com.au/productView.asp?ID=TM3000 --- Edit: add resist pen suggestion

Shivetya 13y ago

Eight paragraph of this article, http://www.washingtonpost.com/wp-dyn/content/article/2007/02/16/AR2007021602102.html http://www.washingtonpost.com/wp-dyn/content/article/2007/02... sounds like a forerunner

snake_plissken 13y ago

i can't whistle! :'[