[DIYbio] Re: Open-Source Spectrometer

So... ~2.5 years later and I just ordered a PCB for the openSpectrometer:
https://github.com/nmz787/open-spectrometer/blob/master/pcb-design/propeller_square/trace_layers.png

After tons of reading about electronics, it still isn't as good as I
can do, but I think it's a good start to at least make sure the
general circuit works as expected/intended... then I can think about
noise reduction a little more. For example I'm only really using 3 of
the 4 layers of the PCB right now, routing power traces through the
3rd layer or changing the layer stack with GND on both exteriors is
also an decent idea, but having signals inside makes debugging hard...
but I'm pretty happy with this for a 'first' pass.

There seems to be a lot of room on the PCB, but I wanted to keep as
much digital out of the ground plane around the analog area. After
debugging I'll probably want to split the board into two, so I think
the room will get diced away and lead to slightly lower board cost
altogether.

Right now, for this 4-layer board, 3 copies of the PCB from OSHPark
was $67.... so <$33 per PCB. Previously I estimated about $46 in
parts, so 46+33 = $79 with no optics (or SD card or USB cable or
housing or upgraded/coated CCD window).

I've added the current files to github, but I'm not sure all the
libraries are there, but that shouldn't stop a determined person from
googling for the missing modules/footprints! I'll figure that out soon
enough!


On Wed, Dec 14, 2011 at 1:59 AM, Nathan McCorkle <nmz787@gmail.com> wrote:
> Here's a first try at a block diagram:
> https://github.com/nmz787/open-spectrometer/blob/master/pcb-design/openSpec_Block_Diagram_1.png
>
> With this design it should be
> A) programmable with Arduino IDE
> B) be adaptable for Ardunio shield or standalone PCB
> C) ~60 fps of RAW uncompressed pixel data sent off-board via either
> USB 2.0 or to the uSD card
>
> Cost for standalone board should be (roughly) something like this:
> $2.82 * 2 - atmega328
> $2.01 - WM8253
> $4.25 - FT232H
> $3 - uSD slot (push/push)
> $20 - CCD (TCD1304AP)
> $1.45 - uUSB B connector (through hole, DX4R005J91R1500)
> $0.26 - EEPROM for FT232H (93LC56B)
>
> $10 for power management and various capacitors, resistors, and crystals
> $20 for PCB, potentially 1/10th that if made at home
>
> Total: $66.61
>
> Plus $150 grating
> Plus $20 aluminum/steel plate for optics (probably a high estimate)
> Add 3D printed case and some 3D printed optics mounts, practically
> free if you have a 3D printer
>
> Total $236.61
>
> Depending on the type of fiber you get (TOSlink vs Thor labs or Wards)
> add $4-$80
>
> Paint/evap on some phosphor/fluorophore to the CCD to allow UV
> detection - maybe about $20
> (this stuff might work, though a different Lumogen is what all the CCD
> UV papers talk about, this may be equivalent:
> http://www.kremer-pigments.com/shopus/index.php?cat=010703&lang=ENG&product=94730)
>
> Add a light source - $20 UV germicidal lamp, $1 CFL, $0.1 LED, etc...
>
> <$350 UV-Vis spectrometer that should be good for DNA
>
> I just got the ADC and Hi-Speed FTDI chips in the mail today, I should
> be able to breadboard them within the next few weeks... then I'll
> probably try to make some PCBs with copper-clad and the laser cutter
> etch method (coat copper-clad with spray paint then etch with laser,
> then with copper etcher)
>
> I've also got a sample of the $150 grating, so maybe I can make some
> progress on a 3D printed tip-tilt mount (hard for me to get started
> because the point of rotation should ideally be at the center of the
> convex grating's surface) for that during my Christmas/New Years
> school break.
>
> We also got in some cheap holographic transmission grating last week,
> the kind that comes in 8.5x11 inch sheets.
>
> Lots to do and play with!
>
> On Fri, Nov 18, 2011 at 7:23 AM, Nathan McCorkle <nmz787@gmail.com> wrote:
>> On Fri, Nov 18, 2011 at 5:37 AM, Nathan McCorkle <nmz787@gmail.com> wrote:
>>> On Wed, Nov 16, 2011 at 2:33 PM, John Griessen <john@industromatic.com> wrote:
>>>> On 11/16/2011 12:10 PM, Cathal Garvey wrote:
>>>>>
>>>>> Wouldn't that
>>>>> mean your "job" would then be to create a "shield"
>>>>
>>>> Your job as product developer is to deliver more bang per buck, so the
>>>> $89 price of a Beagle Bone is hard to resell for cheap. And
>>>> Teensy ardino compatibles are better to design on top of than
>>>> straight "shield" versions with their large connectors and large
>>>> size and large price for newbies.
>>>>
>>>> On 11/16/2011 12:17 PM, Nathan McCorkle wrote:
>>>>> What's the cheapest embedded linux board that's out there that can
>>>>> bring over the 1MB/s from a 2nd micro?
>>>>
>>>> There's more to consider. Why not have the first micro reduce the data some
>>>> also? 1MB/s is raw, very raw. A little filtering by the first micro
>>>> would let you have a cheap flat pack leaded linux running micro instead
>>>> of the all out ones you like. Likewise with the Wifi.. 1MB/s is letting
>>>> your lab instrument do nothing but send raw data... If you reduce
>>>> it reasonably, you still have plenty of room for outside re-analysis.
>>>
>>> In my experience no science compresses their data, except for CERN
>>> maybe... I'm not sure a slow micro could handle a compression scheme
>>> though. Something linux-based could though.
>>>
>>>>
>>>> Having the first processor be a python-on-a-chip one would let users
>>>> easily change the filtering routines and access raw data as well.
>>>>
>>>
>>> I don't like the sound of python on a chip for more than a learning
>>> tool, but my friend said there was a microfluidic controller that had
>>> lots of MUXed pins for valving that ran with a python-on-a-chip
>>> chip... he did say it didn't go anywhere, can't say it was because of
>>> the chip though :)
>>>
>>>> There's just not going to be much interest in the world for the CCD raw data
>>>> though,
>>>> so why send it out? Making an open way to access it as it flies by inside
>>>> the machine
>>>> is better.
>>>>
>>>> The electronics bill of materials should be $20-$30 for two processors,
>>>> one running linux, and USB ports, not including the CCD.
>>>>
>>>
>>> Ok, TI launchpad is $4.30, has SPI, master clock at 16Mhz with
>>> 62.5ns/instruction. Arduino 16Mhz (not sure on timings, probably
>>> similar)... both compile with GCC (this is a feature that I'd like to
>>> preserve no matter what platform) and are coded in C, can optimize
>>> with assembly if needed... Launchpad is cheaper really because its
>>> subsidized by TI
>>>
>>> Link one of those uCs to the CCD, link the CCD out to the nice ADC
>>> with SPI out, link the SPI out to this FTDI SPI-USB virtual com port
>>> chip (FT232H, USB 2.0, win, linux, mac drivers, $4.3), link that to
>>> whatever system you want.
>>> http://www.mouser.com/search/refine.aspx?Ntk=P_MarCom&Ntt=123533426
>>>
>>
>> Seems the FTDI USB driver is supported in rooted Android...
>> http://www.ftdichip.com/Android.htm
>>
>> iPhone has a serial port cable, so pulling the data into the uC and
>> putting it out the UART could work... @57.6Kbps you could sustain
>> about 1 read per second (1 read is 59104 bits), or multi-shot into
>> buffer, then long readout
>> http://blog.makezine.com/archive/2011/07/59-cable-lets-you-connect-iphone-to-arduino-no-jailbreaking.html
>> http://www.redpark.com/c2db9.html
>>
>> either uC would need some extra RAM for buffering, but this is solved
>> and looks easy:
>> http://www.arduino.cc/playground/Main/SpiRAM
>>
>> So that would instantly give you access to a huge market of Android
>> and iDevices, new and used:
>> display, storage, comms (cell, wifi, GPS)
>>
>>> Just found this via the Arduino wikipedia page, near the bottom...
>>> this ($35 100Mhz ARM) or the $5-cheaper 60Mhz might run linux (uClinux
>>> comes to mind) and a web server, then attach the CCD subsystem and
>>> comms dongle via USB.
>>>
>>>> John
>>>>
>>>
>>>
>>> --
>>> Nathan McCorkle
>>> Rochester Institute of Technology
>>> College of Science, Biotechnology/Bioinformatics
>>>
>>
>>
>>
>> --
>> Nathan McCorkle
>> Rochester Institute of Technology
>> College of Science, Biotechnology/Bioinformatics
>
>
>
> --
> Nathan McCorkle
> Rochester Institute of Technology
> College of Science, Biotechnology/Bioinformatics



--
-Nathan

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