Building Scientific Instruments with the Propeller
RJSM
Posts: 68
For many years Ive quietly watched these forums with great interest (and Im yet another Aussie !!). Ive keenly followed the development of the P1 and then the P2; the problems with the latter it seems may have led some forum members to lose interest and perhaps go elsewhere.
Id like to echo the positive comments of others that the P1 has been and still is a fantastic development platform and this seems like the perfect time to inject something completely new into this forum.
Im a chemical physicist with 25+ years in academia. Tiring of university life I moved into the corporate sector with a major scientific instrument company about 4 years ago. Ive been building scientific instruments since long before the P1 was released (in fact as far back as the late 70s/early 80s when I was a grad student at Cornell and postdoc at Stanford) - but nearly all of my recent projects have used the Propeller chip.
In my instruments, Propeller-based hardware teams up with a LabVIEWTM PC-based front end, giving a high quality GUI. For me, the synergy of those two tools comes close to nirvana for rapid development of easy-to-use scientific instruments rivalling the performance of commercial products but at typically 1/10-1/100 the cost. Thats potentially great news for educators with large teaching labs but small budgets.
To whet your appetite Ive attached a couple of photos polarimeter and potentiostat PCB's both P1-based. Without going into any great scientific detail, the former instrument can distinguish and quantify left and right-handed molecules (for example sugars, like sucrose, glucose and fructose) while the latter accurately measures trace heavy metals like Cd and Pb at parts-per-billion levels in water samples. I've also attached pics showing the LabVIEW front panels that control/acquire data from each of these instruments.
These are just two examples from an extensive suite of analytical chemistry/test instruments Ive designed and built using the P1. 12 months ago I had the fortunate opportunity to visit Parallax and show Ken, Andy and Stephanie what Ive been up to.
Im hopefully now just a couple of months away from launching a website that will put all of this information into the public domain, both to promote science and so that others may benefit from my work. The P1 is here and now and Ive never really found it unable to do anything Ive wanted it to it just works, and works perfectly ! Im very excited about a P2 in the pipeline but Im certainly not going to enter a state of paralysis while waiting for either an FPGA image or silicon ! There are just too many projects still waiting to be tackled with what we already have at our disposal.
In the coming months Ill use this thread to keep you posted about other P1-based scientific instruments Ive built/am working on and also about how to access my website when it is ready. Hopefully exciting times ahead...
Id like to echo the positive comments of others that the P1 has been and still is a fantastic development platform and this seems like the perfect time to inject something completely new into this forum.
Im a chemical physicist with 25+ years in academia. Tiring of university life I moved into the corporate sector with a major scientific instrument company about 4 years ago. Ive been building scientific instruments since long before the P1 was released (in fact as far back as the late 70s/early 80s when I was a grad student at Cornell and postdoc at Stanford) - but nearly all of my recent projects have used the Propeller chip.
In my instruments, Propeller-based hardware teams up with a LabVIEWTM PC-based front end, giving a high quality GUI. For me, the synergy of those two tools comes close to nirvana for rapid development of easy-to-use scientific instruments rivalling the performance of commercial products but at typically 1/10-1/100 the cost. Thats potentially great news for educators with large teaching labs but small budgets.
To whet your appetite Ive attached a couple of photos polarimeter and potentiostat PCB's both P1-based. Without going into any great scientific detail, the former instrument can distinguish and quantify left and right-handed molecules (for example sugars, like sucrose, glucose and fructose) while the latter accurately measures trace heavy metals like Cd and Pb at parts-per-billion levels in water samples. I've also attached pics showing the LabVIEW front panels that control/acquire data from each of these instruments.
These are just two examples from an extensive suite of analytical chemistry/test instruments Ive designed and built using the P1. 12 months ago I had the fortunate opportunity to visit Parallax and show Ken, Andy and Stephanie what Ive been up to.
Im hopefully now just a couple of months away from launching a website that will put all of this information into the public domain, both to promote science and so that others may benefit from my work. The P1 is here and now and Ive never really found it unable to do anything Ive wanted it to it just works, and works perfectly ! Im very excited about a P2 in the pipeline but Im certainly not going to enter a state of paralysis while waiting for either an FPGA image or silicon ! There are just too many projects still waiting to be tackled with what we already have at our disposal.
In the coming months Ill use this thread to keep you posted about other P1-based scientific instruments Ive built/am working on and also about how to access my website when it is ready. Hopefully exciting times ahead...
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Comments
http://forums.parallax.com/showthread.php/160016-First-attempt-at-building-a-P1V-image-for-the-BeMicro-Max10
out of that may come hardware that sits between P1 and P2 and would be well suited to instrument development.
I must say that you write very well and welcome to the forums.
I am not a scientific type of person, but I like creative thinkers. A while back, actually several years ago, I thought about trying to interact with the prop through Lab View, because I had a temporary license from a previous employer, but I never followed through with it. It is so cool to see someone actually putting the two of them together and displaying pics. I hope to hear a lot more about your creativity and use of LabView.
Bruce
thanks very much for your comments. I've been using LV for quite some time now. While the full development environment is quite expensive, LV allows you to take your vi's and generate a runtime executable that is free distributable without any licensing fees. In the education area, that's a real bonus when budgets are often stretched.
I'm sure you are also aware that once your data is uploaded (in my instruments via USB-to-serial interface) to the PC, LV has numerous powerful algorithms for data processing (things like Savitsky-Golay filters, FFT etc etc) Why re-invent the wheel when all that is already built-in.
Richard
To be perfectly honest, I only played with LabView for about a week or two, but pretty extensively during that time frame, just learning the environment. I must say that I was very highly impressed with the software, because it was just simply amazing, with all the various controls and the GUIs that you could create. After having developed software for Windows, I am very GUI oriented. I like it a lot when a GUI looks nice and functions very well. I can only imagine how much time and money NI must have invested into that software.
Bruce
Yes I've been following what ozpropdev has been up to and it is certainly great stuff !
I've dabbled a bit with FPGA's in the past, particularly for image acquisition from scientific grade CCD's.
Here's a happy snap of a PCB I put together that allows me to run an 8 cog P1V and access an on-board 256kx16 SRAM via use of ports A and B. The slick yellow module that you see on the PCB was designed by a guy in Brisbane, here in Australia. Sadly, he's no longer making these but has made the design open source, I believe. Same FPGA here as on the DE-0 Nano.
I'll have more to say about all of this down the track.
Richard
Hi, and welcome to the Forum.
Excellent designs and it's great to see the info and pictures.t. I was curious about the K1 "Goodsky:DIR - SPST DIR-S8-105-A" and had to look it up. LOL
I played with Labview for a few months a few years ago. I did 2 of their FPGA courses but never really got to use any of it. Unfortunately I don't have access to the software anymore.
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For anyone else interested:
Propeller Potentiostat
U8
TL074AC
TL07x Low-Noise JFET-Input Operational Amplifier
http://www.mouser.com/ds/2/405/slos080l-316255.pdf
U10
LMC6001
Ultra-Low Input Current Amplifier
http://www.ti.com/lit/ds/symlink/lmc6001.pdf
U6
1865 / 623:
LTC1865 - µPower, 16-Bit, 250ksps 1- and 2-Channel ADCs in MSOP
http://www.linear.com/product/LTC1865
U7
AD623
Instrument AMp:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD623.pdf
U9
ADG508AKR
CMOS 4-/8-Channel Analog Multiplexers
http://www.analog.com/media/en/technical-documentation/data-sheets/ADG508A_509A.pdf
K1
Goodsky:
DIR - SPST
DIR-S8-105-A
http://www.goodsky.co.uk/datafiles/DIR.pdf
U5
MAXIM Integrated:
MAX1673
Regulated, 125mA-Output,
Charge-Pump DC-DC Inverter
U4
FTDI FT245RL
http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT245R.pdf
U2
Microchip
24LC256
CMOS serial EEPROM
http://ww1.microchip.com/downloads/en/DeviceDoc/20001203U.pdf
U1
P8X32A_044
http://www.parallax.com/product/p8x32a-q44
U3 ? I can't read the numbers (looks like a voltage reg)
I'll look forward to seeing your website when it's finished.
Welcome to the forums, but you said you have been around awhile.
Thanks for the great write up and great pictures.
Welcome! Looks like you build some nice instruments!
For one-off projects, I've used MakerPlot with the Propeller and assorted microcontrollers - it is not LabView, but has a very affordable lab license.
On the subject of making things "low cost, high performance" (is that an oxymoron ?) I continue to be amazed at what is possible.
I'm a spectroscopist and that basically means using light to record the signatures of atoms and molecules. Spectral signatures can arise due to absorption or emission of radiation. The amount of light that gets absorbed or emitted can be related to concentration - which is why spectroscopy is so important for chemical analysis.
Sometimes we use very short pulses of light to excite molecules to fluoresce (e.g. pulsed lasers). For example a molecule like quinine (found in tonic water) if excited by pulses of near-UV light will fluoresce in the blue region of the spectrum - and the timescale for the emission is very short - just a few tens of nanoseconds.
One of the P1-based instruments I've made uses an LED to generate nsec pulses and a technique called photon counting to detect these pulses. The instrument can then be used to measure these very short fluorescence lifetimes.
Take a look at this LabVIEW screen dump and you'll see a pulse profile of a Nichia 370 nm UV LED, generated and measured by a Propeller. The FWHM of the LED profile here is ~ 2.5 nsec !
On my website i'll have lots of experimental data like this to demonstrate many of the neat things you can do with scientific instruments.
Richard Morrison
Excellent work mate!
Looking forward to your future contributions.
Cheers
Brian
BTW. A few of us are based in Melbourne and catch up when we can to talk all things Propeller. Where are you based?
Small world - i'm here in Melbourne too (Caulfield). Happy to join the local group for Prop discussions.
Cheers
Richard
Totally agreed there is still a lot we can do with the P1.
Love your projects. Looking forward to hear more about them.
Ray
Looks like our local gatherings are about to get even more interesting.
Thanks for taking the time to present what you're doing. I think labview is great for getting things going, I'll be interested how the gui translates to the prop, but the prop should be good for this kind of thing.
That fpga module is interesting - but looks like the fpgamodule.com site has gone. Do you have any other links?
regards
Lachlan
sure - you can find documentation for the FPGA module at https://github.com/thin-layer/helix_4_fpga_module. There's a complete set of Altium design files there and a nice pdf with the module pinout too.
The modules were not expensive at around $40 - there were 4CE10 and 4CE22 variants; each module had an SRAM but there was also a beefed up version with DDR2 DRAM as you'll see when you get the zip file.
I communicated with the designer quite a bit around 6 months ago. I thought his modules were just the ticket for dropping into projects and soldering them onto a motherboard was trivial - so I ended up setting one up as an 8 cog P1V as you saw in the photo.
Sadly though, the modules didn't exactly sell like hotcakes, hence the disappearance of the website, as you discovered. Luckily I bought up the rest of Brent's inventory before that happened ! I did talk to him about doing another production run but that never happened.
It would be great to have a local gathering - how regularly do you guys do that ?
Richard
You Aussies really stick together, all while hanging upside down on the earth!
Want proof...
Land (earth) is heavier than water.
There is more land in the northern hemisphere and more water in the southern hemisphere.
Hence the land part would fall to the bottom
Therefore, Oz is on top
Really interesting little module, thanks for the links Richard. Wish I had known about it at the time.
Regarding how regularly - too early to establish a pattern, but every few months (or when another prophead is in town, or someone has something new/interesting that needs appraisal). Always worthwhile.
It seems there are a few Prop guys in Melbourne and I always like visiting the place although normally I don't have much time but if we all can make a date in April sometime then I may pop down for a couple of days.
How about a hands-up firstly from all the Aussies reading this and secondly who might be interested in a workshop get-together down in Melbourne in April? I gather that there are a number of suitable places we could meet.
If there is enough interest we could maybe formalise it into more of an UPEDU (down under) or at least plan such an event. Maybe we might even have a P2 image by then.
Peter (and others) if you ever have a few hours spare down here, let us know. It's a standing offer.
We all seem to be out east / south east and fairly flexible
Optical detectors such as photomultiplier tubes and photodiodes produce small currents. Less well known is the fact that LEDs can also be used as optical detectors.
Im currently documenting a USB-enabled, P1+LV-based instrument that measures and logs very small currents and voltages. My instrument allows direct connection of a large number of sensors - with all necessary data acquisition circuitry on-board.
The tests Im carrying out at the moment are using a water clear 5mm LED (in this case a turquoise green emitter), using the instrument to measure the photocurrent produced by this LED under illumination.
Questions :
How tiny a current/voltage do you think it might be possible to measure with a low cost, Propeller-based instrument ? The instrument is to draw its power from a laptops USB port and Im interested in demonstrated, not theoretical performance.
What current would my LED detector produce in the dark, and then under ambient room light conditions, and how much noise would one expect in these measurements ?
If one were to shine red, and then blue light from LEDs onto this detector, what response(s) might we expect ?
Before spilling the beans, Id be curious to hear the thoughts of others !
This instrumentation project is really nicely suited to use of a P1 Propeller and the results I think are quite remarkable. I hope be in a position to post some data (that will answer the above questions) and more technical information about this instrument in the coming week.
Richard
One tenth to one hundreth the cost........ This is something I have long suspected to be true of the Propeller. It is also indicative of there being enough of a difference in cost and market price of finished product to allow innovators to make a reasonable profit for their efforts. (Maybe as an educational device supplier.)
The Chinese have even gone so far as to translate the Propeller Manual into Simplified Chinese. That seems to indicate that they too see the value in this alternative architecture.
The public consumer may be fickle as to which processor gets the buzz, but having people that really invest a great deal of time in creative research on Parallax's side is greatly appreciated.
++++++++++++
I can't answer the LED question, but would like to see the answer as well.
I do know that the Red LED will accept a broader bandwidth of light than a Blue LED, with other colors in between in the ROY G BIV sequence of colors. There has been a few projects using LED as touch switch sensors sampling the voltage/current produced from ambient light.
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Also, I think Parallax would love to hear your thoughts on what the Propeller 2 might add to your present scheme.
I presume you are aware of the work on LED light detection by Forrest Mims. He as many publications on the topic especially w.r.t. atmospheric measurements: http://www.forrestmims.org/publications.html
Forrest Mims was the pioneer in that application of LED's. He has done some wonderful work on atmospheric aerosol and column ozone/water vapor measurements using LED detectors, and who could forget his classic Engineer's Mini-Notebooks, published by Radio Shack. Inspirational stuff !
Richard
re: What current would my LED detector produce in the dark,
Zero
re: : What current would my LED detector produce and then under ambient room light conditions,
it is dependent on the brightness of the light source and the color of the LED .Also the shape of the LED may affect it (round vrs square, flat vrs round etc)
Red will produce the less current , red, yellow, and green will produce the most current.
re: If one were to shine red, and then blue light from LEDs onto this detector, what response(s) might we expect ?
You will have less current flow with the Blue LED
What current would my LED detector produce in the dark
None
Am I correct or off in the weeds?
Hi Richard
I did the Forrest Mimms LED as light detector experiments, and originally used a BASIC Stamp to measure the rctime (time to discharge to zero) for a reverse biased LED to discharge under various lighting conditions. One set of results was:
Blue LED can detect light from a Blue LED.
Green LED can detect light from Green and Blue LEDs.
Red LED can detect light from Red, Green, and Blue LED.
Red works best with red. I was about to determine if same color works better or red works better for all cases, but I was distracted by another project and 15 years went by.
In any case, the current is very small, but if you can reverse bias the detector LED, it will discharge in a short time (under half a second?), and sooner with more light applied. I only used two LEDs, but with a proper instrumentation amplifier circuit it might be more senstive.
Do you have any evidence that "the Propeller is preferred for scientific tools" ?
My guess is that the world is full of thousands of scientific tools and some vanishingly small percentage of them use a Propeller.
Certainly a vanishingly small percentage of the world knows anything about Spin/PASM. Be sure determinism is not unknown outside of Spin/PASM.
The control software of the F-35 Joint Strike Fighter is in C++. A deterministic, real-time application if ever there was one.