ARLISS Team NH
Andrew (ARLISS)
Posts: 213
Hi all,
You may remember some of us from a thread posted last year (tinyurl.com/28zw9kf). Last year, we launched a Board of Education with a Sensirion SHT11 temperature/humidity sensor, real time clock, and a USB data logger to approximately 12,000 feet at ARLISS (www.arliss.org). We are returning to launch our payload once again in the Black Rock Desert, Nevada, this September. Our team has decided that we would like to add a carbon dioxide sensor to our current configuration but several questions arise:
1) Will the Parallax CO2 sensor fit on our breadboard? Take a look at the attached picture. Do you think there is any possibility of the CO2 sensor fitting as the configuration currently stands? We have discussed the possibility of mounting the sensor elsewhere and routing the wires to the board.
2) Are there currently enough I/O 'slots' available? If there aren't enough, what are our options?
3) Do we have enough program memory? As I recall, the most recent version of our program almost filled the EEPROM of the BS2 stamp. We have discussed the possibility of changing to a BS2e, but what would be required in order to do so?
Links:
CO2 Sensor Module - http://www.parallax.com/Store/Sensors/PressureFlexRPM/tabid/177/ProductID/616/List/0/Default.aspx?SortField=ProductName,ProductName
Thank you,
Andrew Mahn
Student Project Lead
ARLISS Team NH
You may remember some of us from a thread posted last year (tinyurl.com/28zw9kf). Last year, we launched a Board of Education with a Sensirion SHT11 temperature/humidity sensor, real time clock, and a USB data logger to approximately 12,000 feet at ARLISS (www.arliss.org). We are returning to launch our payload once again in the Black Rock Desert, Nevada, this September. Our team has decided that we would like to add a carbon dioxide sensor to our current configuration but several questions arise:
1) Will the Parallax CO2 sensor fit on our breadboard? Take a look at the attached picture. Do you think there is any possibility of the CO2 sensor fitting as the configuration currently stands? We have discussed the possibility of mounting the sensor elsewhere and routing the wires to the board.
2) Are there currently enough I/O 'slots' available? If there aren't enough, what are our options?
3) Do we have enough program memory? As I recall, the most recent version of our program almost filled the EEPROM of the BS2 stamp. We have discussed the possibility of changing to a BS2e, but what would be required in order to do so?
Links:
CO2 Sensor Module - http://www.parallax.com/Store/Sensors/PressureFlexRPM/tabid/177/ProductID/616/List/0/Default.aspx?SortField=ProductName,ProductName
Thank you,
Andrew Mahn
Student Project Lead
ARLISS Team NH
1280 x 960 - 467K
Comments
For the input and output slots, are you talking about the two black rails and if so, are they just power strips? Do they have to be side by side? Or are you talking about if there is enough space on the bread board itself, even if we have to wire it somewhere else? Because if i recall correctly, you need a designated hole for the Volts. And I think we could use any BUS to attach the CO2 sensor. So wiring space should not be a problem.
Couldn't we just use a different file, add the programming needed, see what the size is. Then compare it to what we have left?
Post Edited (Dylan Landry) : 5/23/2010 2:47:55 PM GMT
Would moving the datalogger to the other side be a big issue? Would it involve moving a lot of wiring?
Thank you for your reply
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Powered by enthusiasm
SRLM,
Thank you for your advice. Could you please explain what reorganizing the "program to fit between multiple slots" involves?
Thank you,
Andrew
·· Thanks for activating the forum. When·team members e-mail "to all" with technical questions or ideas, please encourage them to post to this forum instead. That way we'll have a running history of ideas, questions and answers for everyone to see.
You make a good point about the CO2 sensor being an 'alarm' rather than a true sensor. Although it can be programmed to activate an alarm at a certain CO2 concentration, doesn't it make sense that it must also be measuring (but not necessarily outputting) C02 concentration...? We have to answer that question before we move ahead with integrating it into the ASP-2. What do our friends on the forum think?
Thanks for posting the picture of the ASP circuit board. Can you post the "final" ASP program code from last year for everyone to see? That will help everyone·understand where the wires, sensors, etc. are located and how much space is (or isn't) available on the BOE circuit board, in the BS2 memory, etc.·I'm eager to hear·what Dr. Allen and Sylvie have to say. Have you seen them on the forum?
Standing by--
Mr. Kibler
Sunday - 4:30 PM
The DataLogger is the small circuit board that the flash drive plugs into. The DataLogger then plugs into the Board of Education (the BOE, which is the main circuit board.) Remember that the BOE is the main circuit board. People who log into the forum will use 'BOE' a lot. The BS2 (or BS2e) is a programmable stamp-sized memory chip that plugs into the BOE. In fact, almost everything plugs into the BOE--- sensors, wires, etc.
Mr. Kibler
·· If·you were to·"extend the wiring" and mount the CO2 sensor module·on something other than·the BOE, would you·just solder a wire onto each of the·four CO2 module plug-ins...? Don't the plug-ins connect to something on the under side of the breadboard?
Mark (Team Advisor)
From the pic, it looks as if you have p3, p4, p6, p14 and p15 avaliable on the stamp, you can connect the co2 module to any of these for the co2 module input·and program to do whatever when the preset co2 level is reached and triggers the co2 module output.
Post Edited (kf4ixm) : 5/23/2010 10:38:14 PM GMT
Andrew
EDIT: Oops, I lied. I just attached a newer version.
Post Edited (Andrew (ARLISS)) : 5/23/2010 11:29:01 PM GMT
We don't want·the CO2 sensor·to function as a CO2 alarm. What we'd like is for·the CO2 sensor to output and record·ALL CO2 measurements to the DataLogger/ flash drive (along side the temperature, humidity, flight time and altitude data which our current BOE already records.) Our primary question is: How do we get the CO2 sensor to output and record·ALL CO2 measurements to the DataLogger? What do you think? Does anyone else have any ideas...?
Here are your homework questions...
1-What is the typical concentration of CO2 you would expect to find in the atmosphere, at different altitudes?
2-What is the typical concentration of CO2 in the air that is exhaled by a human being?
3-Find a sensitivity curve for the Parallax sensor, and compare it with atmospheric CO2 levels.
All told, you need to establish whether or not this sensor suitable for your purposes.
Then figure out how to implement it. The output of the sensor board is a threshold switch, but one of the test points also has an analog output proportional to CO2 concentration. That would be more interesting, if the sensor is promises to yield useful data.
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Tracy Allen
www.emesystems.com
1. The average amount of CO2 in the atmosphere is 387 ppm, or 0.0387% by volume.
2. The average amount of CO2 in a human breath is 43.8ppm, or 0.0043% by volume.
3. See attached.
MG811 sensor data sheet - tinyurl.com/2eoyjnl
It's great to have you back with us and to be working together again. Thanks for giving the team·a homework assignment.·You may·get bombarded shortly with replies from ALL of this year's team members/ candidates (which is exactly what we want to happen.) Then what...?!
I'm both curious and excited to see where·this year's project goes.·It's always a new and exciting adventure, and excellent learning.·Thanks so much for your help.
Standing by,
Mark
I've had an exciting year working with the fruits of last year's efforts. Yesterday I flew the XBee-MAWD telemetry rocket for the 10th time, getting good data again. I also presented it at the Unofficial Propeller Expo Chicago last weekend, and yes,·I did mention your project as the inspiration/starting point.·Still working on putting together that article.
Paul
Andrew, or someone, please recheck the figure for exhaled air.
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Tracy Allen
www.emesystems.com
This might be a good time for the students to stop and discuss what kind of answer would be reasonable, based on their understanding of respiration, before trying to find the exact number.
Alright, from some quick research an average exhaled breath contains about 5.3% CO2 by volume, or 53,000 ppm. Does this sound right? And if I may ask, how is this related with integrating a CO2 sensor with our ASP?
Thank you,
Andrew
Source: www.newton.dep.anl.gov/askasci/zoo00/zoo00065.htm
It's great to hear from you and it's great to be together again. I hope you'll be working with us again on this summer's project, the ASP-2.·We're adding a parallax CO2 sensor to the BOE so we can measure yet another greenhouse gas parameter.
·The team from "Mad West" sure showed their stuff at last year's TARC finals, didn't they. I'd say they·had some excellent mentoring...!
Thanks for pointing out that 338 ppm is not necessarily the same as 0.00000038% CO2 by volume. The kids are checking their·"facts" and they will post updated and correct information (from at least three sources) later today.
Notes to ARLISS Team members, including Tracy and Sylvie,
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I just spoke with Dave at Parallax Tech support and here’s what he had to say about using the Parallax CO2 sensor:
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········· CO2 concentration, as we determined yesterday, is measured and recorded in ‘parts per million’, or ‘ppm’. That’s a standard unit and so we will use ‘ppm’ in our data/ DataLogger.
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········· How you set the CO2 sensor’s potentiometer (which is a very low resistor) determines the sensor’s sensitivity.
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········· The potentiometer has two settings: “high” and “low”.
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········· Set the sensor “high” for higher concentrations of CO2, lower for lower CO2 concentrations.
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········· The CO2 sensor has two other (?) settings:
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········· The “trigger level” (ppm = ?) determines when the CO2 sensor’s alarm is activated.
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········· The “set point” triggers an audible alarm on the CO2 sensor.
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········· Question from Mark: Can we set the “trigger” setting so low (0.00000000001 for example) to make the sensor turns on automatically when the BOE is powered up?
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········· In the program code, if “alarm > 1 then debug” (I think this means that an electrical impulse or “output” is sent to the alarm if “alarm > 1“, turning the alarm on.)
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A (Parallax, etc.) computer program simple reads an electric impulse and converts it to numbers, makes it triggers a alarm, etc. If the output can be converted to “ppm” instead of using it to trigger the CO2 alarm, the CO2 sensor might work on the ASP-2 to measure and record CO2 concentrations and correlate it with altitude. I think…
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What do others who are more knowledgeable in programming think? What are your thoughts, ARLISS team members?
Thanks!
·
Mark
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Would you mind confirming this information (5.3% CO2) from at least two other scientific sources? Be sure to include where you got the information in your reply.
Read my post below. I think Professor Allen is trying to get us to figure out how low or high to set the "threshold limit" on the CO2 sensor. But maybe I may be·mistaken.·I'm eager to hear. Let's be sure we get accurate information so he/ we·can make a well-informed decision. Thanks!
Mr. Kibler
"Qui peut dire le faut et le real?"
Please post your three scientific sources and what they have to say about CO2 concentration as soon as you have them. Be certain that your information is accurate. All three numbers should be very close but they will not necessarily be the same number.
Mr. Kibler
It is always a good idea to check figures from different sources. Atmospheric concentration varies with the seasons and from location to location, and maybe with altitude. How much variation? Similarly, exhaled air varies from person to person under different circumstances. How much variation in that? Notice especially that there are always about two orders of magnitude difference between atmospheric concentrations and exhaled air.
Andrew said, "And if I may ask, how is this related with integrating a CO2 sensor with our ASP?" Why compare CO2 concentrations in the atmosphere with exhaled air? There won't be any exhaled air in the rocket? I want you to think quantitatively about what you are trying to measure.
Come up with a voltage that you might expect to see from the Parallax sensor when it is exposed to those levels. The exhaled air is a comparison point. Here is the graph you found in the data sheet that is available on the Parallax web site. What voltage level would you expect to see from the sensor when exposed to atmospheric CO2 and to an exhaled breath respectively? (approximate okay).
Parallax sells both the raw sensor (605-00010) and that same sensor mounted on a PCB with support circuitry (27929). The raw sensor does need support circuitry to interface with the Stamp.
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Tracy Allen
www.emesystems.com
Tracy also made an earlier comment about a 'test point' on the sensor that could be used to bypass the "all or none" (alarm) nature of the sensor. I'm interested in hearing more, and I think you guys should be as well.
Post Edited (sylvie369) : 5/24/2010 7:48:26 PM GMT
2.) 4% of all chemicals in a human breath is CO2. 450 mL of CO2 is exhaled per minute.
3.) Working on it.....