How much power is it going to take to run all the electronics? We would need to find this out first before we can find out if the battery would be sufficent enough.
Tracy,
This seems important to note: PIN 3 and PIN 4 are not assigned or defined in·Andrew's "MAWDBOECO2_w_ADC_TEST -·June 21, 2010" program. The wires to these pins come from the CO2 sensor's ALR and CNTL/HSW
CNTL/HSW <---- goes to ---->· PIN 3 on the BOE
ALR··········<---- goes to ----> PIN 4 BOE
Though we haven't mentioned it much, PIN 15 is taken by the MAWD. It is defined in the program as "MAWDin".
How much power is it going to take to run all the electronics? We would need to find this out first before we can find out if the battery would be sufficent enough.
Justin
Justin,
·· Dylan asked the same question·just two hours·before you did (read his post to the forum):
1.) What is the total Amp drainage of the current ASP build?
2.) What is the combined Voltage requirement of the current ASP build?
3.) What are some Voltage limits of some of the components on the current ASP build?
My answer (posted below) was:
Dylan, you could look at the documentation sheets for each of the parts on the ASP. See what each requires for amperage and then do the math. For example, if the total amperage "draw" (usage) for all the parts happened to be 1000 mA, and if the battery is a 5000 mAH battery, then it should run the ASP-2 for 5 hours...
So the short answer is, read the documentation, see how much amperage each component uses, then do the math. This is homework for the Team. The specifications for our battery are posted below.
This is not a competition to see who can finish first but rather, an opportunity for the the Team to work together to solve·a problem.·Communicate and collaborate, Justin. "Talking with your lab partner IS allowed." Take a leadership role. Solve the problem together.
Dylan, was it you who said you have a very nice multimeter from your grandfather? A multimeter can measure milliamps in additon to Volts and other things. Do you know how to do that? I'd like you to measure the current drawn by the CO2 sensor module, both when the heater is on and when the it is off. Remember, the ASP-2 can turn the heater on and off under program control. We should also find out how long it takes for the CO2 sensor to "warm up". That could be a few seconds, or on the other hand, it could be many minutes. Being able to control the power of external devices can be a great help to save power or to hunker down to critical tasks if the battery is low.
The power consumption issue is complicated by the fact that some loads are not constant. For example, the USB datalogger uses more power (lots more) when it is writing data to the thumb drive than when it is just sitting there. How do you think you will account for a load that spends a percentages of time at different power hunger levels? Evaluate the parts first, then the whole ASP.
I recall that Phidippides had a dead man switch, a wood dowel in a socket, I think, that was pulled out to turn on power when the rocket separated at some point in its trajectory. Am I remembering correctly? And that is no longer the plan, huh? Now the ASP-2 will operate from ground to apogee to landing and after?
Why a 9.6V battery instead of a 7.2V one? What in your system needs 9.6V? I ask because a 7.2V 5Ah battery is lighter weight. A 5Ah NiMH is a hefty battery, and if it is well charged, I am not too worried that you will run out in two or three hours. It's not too heavy for the mission, right? What weight of payload can you carry in this beast of a rocket, anyway?!!
Mark, I am still puzzled by the readings you are reporting. It sounds like there may not be a good connection between the TP1, TP3 test points and channels 0 and 1 on the ADC. Maybe it is the soldering that needs to be done. It is too sensitive and it seems that the effect when you breath on it is not so much due to the CO2 sensor as it is to Murphy's law of vaporous condensation! It will be very useful to have a connection from TP3 over to the MCP3202; that will be a good reference for testing. You will know you have it right when you can adjust the calibration potentiometer from one end to the other and see the screen reading go from 0 to 2730 counts, (0.0 to 3.3 Volts).
I'm pretty much west coast now, as I have lived here since I was 17. My own dad was in government service and we moved around. I was born in Denver, but spent 3rd to 8th grade in Michigan, and 9th to 12th grade at McLean H.S. in Virginia just outside D.C, and finally to California. I spent my summer between HS junior and senior year in an electrical engineering program at the U. of Virginia at Charlottesville VA and at Ft. Mammoth NJ. I remember well teachers I had at that time, and projects with friends. A lot had to do with ham radio, and trying to listen in on the space program and other activities which shall not be fully reported although we managed to stay out of trouble! I appreciate what you are doing with the rocketeers with these exciting and constructive activities and am happy to help when I can.
·· Guys, because you don't have a complete ASP at home to work with, I think your best approach is to read the documentation for every one of the components, find out how much amperage each one uses, then add all the amperages together to get a total. It would be tough to measure actual amperage while the ASP is running because:
1) We would need 6 people and 12 hands to hold all the voltmeters needed to connect to every device on the ASP when it's running.
2) The amperage varies (changes) on each device when it runs. So I think it might be hard to record because it would read read "high", "low", "high", "low", etc... on each device.
3) Our actually "meeting·time" is severly limited so doing step #1 is not an option for weeks. And we only have two voltmeters...
I would look at the documentation and add all the "amperages required" together.
Dr. Allen believes that the battery we're using has plenty of power storage capability (see his comment directly below.) I agree, but let's prove it with math.
Andrew, please guide this discussion.
Good work~ Good morning (yawn),
Mr. Kibler
dylan landry wrote:
> Dear Mike,
> Test? You mearn like attach a voltimeter at certain TP to see ramaining
> voltage + mAH before and after to see the requirements?
>·
> (Last email, gotta snooze)
>·
> Dylan Landry
>
> On Tue, Jun 22, 2010 at 11:58 PM, Mike Prindiville ·wrote:
>>
>> Dylan, do you think we should test it?
>>
>> ________________________________
>> From: dylan landry
>>
>> Dear Project Team,
>> Mr. Kibler has recently assigned questions for us to fill out.
>> __________________________________________________________
>>
>> QUESTION: Will our battery be "dependable" enough for the mission we have
>> planned? Yes, or no? Defend your answer with facts and details, not vague
>> speculation or science fiction. If you're not certain, write a simple plan
>> explaining how we can/should find out.·
>> This question is quite challenging. We will need a lot of information to
>> answer it.
>> 1.) What is the total Amp drainage of the current ASP build?
>>
>> 2.) What is the combined Voltage requirement of the current ASP build?
>> I believe that if we combine all of the voltage requirements for the
>> current ASP build, we will get the answer to how much volts it needs. But I
>> have a feeling that I am dearly wrong on that one. Any help would be great.
>> But I am a little bit sure that if you do combine the mAH needed that you
>> will get your answer· to if it has enough mAH. Again, any help would be
>> great. First, we need to find out if what i just said is correct : ). Once
>> we get that cleared we can assign each other certain parts of the ASP, get
>> there requirements then have our answer.
Why a 9.6V battery instead of a 7.2V one? What in your system needs 9.6V? I ask because a 7.2V 5Ah battery is lighter weight. A 5Ah NiMH is a hefty battery, and if it is well charged, I am not too worried that you will run out in two or three hours. It's not too heavy for the mission, right? What weight of payload can you carry in this beast of a rocket, anyway?!!
Tracy,
We're using a 9.6 volt Ni-Cd battery because it was what we had available. Our budget, as always, is very limited. If we wanted to achieve a higher altitude-- and if we were building the rocket, too-- I would make everything much lighter, including the battery. Weight isn't a real consideration because the rocket motor is pretty powerful. Physical space is the most limiting factor.
I'm packing up the ASP until we get back to NH tomorrow afternoon. I have to retrieve Christopher from freshman orientation and (maybe) go to an Orioles game at Camden yard this evening. I'll be checking in regularly until we leave for NH.
E-MAIL RECEIVED FROM ANDREW (in Florida). Thanks, Andrew! Excellent leadership.
"Dylan and others,
Thank you for reiterating these questions. While they may not seem important on the surface, they are in fact very mission critical. Mr. Kibler may remember when we added a large piezo buzzer to the NASA SLI robot, last minute. We only tested the robot on the ground for a couple of minutes, but never actually stress tested it. If we had, we would have learned that the robot, even with a brand new and fully charged 9v lithium battery, would only last (consistently) for just a few minutes. After the few short minutes of battery life, the battery dropped below the minimum amount of electricity required by the components, and the robot reset itself numerous times, which was evident in the data log when we analyzed it later {Mr. Kibler notes: This actually happened to the robot during our second trip to NASA...!}
As Dylan first suggested, you might consider taking a look at the electrical draw of each of the individual components and adding them up together. Then, you might consider looking at the specification sheet for the current battery (yes, they have them for batteries too) and interpreting whether or not it will suit our needs. More importantly, let's assume that the battery we have will not last long enough. Then what? Answer that, as well as the other questions below. Try to answer them independently and please show your methods and data, so it's easier to compare our solutions.
Dear Andrew,
I have just hit a roadblock, what are all the components on the ASP anyways? Andrew, could you possibly get that, "Build List" that you where making to me. I, and i'm sure others, have no idea of what components are attached to the current ASP build.
Somewhere in another thread in these forums someone recently said that people shouldn't work with electronic parts until they know what they're doing. To some extent that's true, of course, but to a great extent, you learn what you're doing by working with the parts and making some mistakes.
Having a robot that continuously reset itself was probably a great lesson about what kind of power supply you need. I learned that a somewhat harder way, involving lots of smoke and the frying of two $19 boards. In retrospect, knowing what I know now, it was obvious, but I don't think I would have learned about being careful about total current draw without having made that mistake myself.
There are some other issues I still don't understand having to do with power supplies, including the ability of a supply to provide a certain amount of current quickly, which is a big issue for rocket motor and ejection charge igniters. I see people talk about the "internal resistance" of batteries when they explain that, but I don't yet understand it. I will.
An Orioles game sounds like a blast. Camden Yards is definitely on my list of stadiums to see.
Obviously I picked the wrong team in the World Cup. France completely melted down in an utterly graceless way. I cannot defend any of that.
Spain, on the other hand, seems to be resurgent, and I'm excited about that.
Sylvie, I see you are following the World Cup too! I love soccer, I can see Brazil taking the World Cup this year, but my other guesses are Ghana or Cote D'ivoire (Ivory Coast)... alot of ties going on right now, which I like to see, much better than blow outs ! Enjoy your trip Mr. Kibler!
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔ "Learn to obey before you command."
The main devices you're going to need to worry about (as far as current draw) are the microprocessor itself (whichever version of the BS2 you're using), the datalogger, the CO2 sensor, the real time clock chip, the 3202, and the other sensors you're using (just the SHT11 humidity sensor, right?).
So you've got these devices to worry about powering:
BS2e (correct?)
USB Datalogger
SHT11 Humidity sensor
CO2 sensor
1302 Real time clock chip (correct?)
3202 ADC chip
I believe that you're powering the MAWD from its own 9V battery. Is that correct? If so, then you do not need to figure it into your current draw. If that's not right - if you're running it from the same battery and/or power supply, then you have to figure it as well.
The six devices I listed above are all Parallax products, and I believe that you can find the current draw for each in the product pages. I just looked up the Memory Stick Datalogger, and it's there. So are both sensors, and the RTC chip. You should be able to find what you need, though you'll have to snoop around a bit in the documentation.
===================
I see that both the US and England won, and have advanced to the round of 16. Still have my fingers crossed for Spain.
Post Edited (sylvie369) : 6/23/2010 4:36:02 PM GMT
sylvie369 said...
The main devices you're going to need to worry about (as far as current draw) are the microprocessor itself (whichever version of the BS2 you're using), the datalogger, the CO2 sensor, the real time clock chip, the 3202, and the other sensors you're using (just the SHT11 humidity sensor, right?).
So you've got these devices to worry about powering:
BS2e (correct?)
USB Datalogger
SHT11 Humidity sensor
CO2 sensor
1302 Real time clock chip (correct?)
3202 ADC chip
I believe that you're powering the MAWD from its own 9V battery. Is that correct? If so, then you do not need to figure it into your current draw. If that's not right - if you're running it from the same battery and/or power supply, then you have to figure it as well.
The six devices I listed above are all Parallax products, and I believe that you can find the current draw for each in the product pages. I just looked up the Memory Stick Datalogger, and it's there. So are both sensors, and the RTC chip. You should be able to find what you need, though you'll have to snoop around a bit in the documentation.
===================
I see that both the US and England won, and have advanced to the round of 16. Still have my fingers crossed for Spain.
Sylvie,
You've got everything listed correctly. We can plan on using a BS2e, not a BS2, and I already have one installed in my ASP-2 mockup. As you said, the MAWD is powered by it's own battery. I'll dig up all those data sheets later, and see what I can find. Team members -- please do the same, as we have been discussing via e-mail recently.
I may be mistaken, but didn't the ASP also record TEMP?
Excellent observation, and a good answer from Andrew.
I think that when you look at the current draws of these various devices, you will learn something very interesting. It's an excellent exercise. I sure wish someone had put me through this when I was your age (I believe we had electricity at the time. I know fire had already been invented).
The SHT11 is also known as the Sensirion Temperature/Humidity Sensor correct? I believe I found the correct one on Parallax but I am not entirely sure. Here is the link to the Sensirion Temperature/Humidity Sensor.
· Good work! THIS is what we're looking for to determine how much amperage the ASP will use. This is what you need to know to calculate the answer to the question, "How big of a battery (how much amperage) will the ASP need? Our battery is a 5000 mAH (milli-amp-hour) battery. That means the ASP could use 5,000 mA for one hour, 2,500 mAH for 2 hours (2,500 x 2), 1,666 mA for 3 hours (1,666 x 3), 1,250 mA for 4 hours, etc. ·
On Wed, Jun 23, 2010 at 2:14 PM, dylan landry wrote:
Dear Project Team,
·· Ive gotten the mAH count for all the components, but I have had trouble reading the BS2e data sheet. Apparently, it is 30 mAH per PIN input/output. I am not sure if I am reading this correctly but that is what I got.
mA requirements of each component:
BS2e= 30 mAH per PIN input/output
Datalogger, Standby= 2mA, running= 25mA
SHT11 = N/A (Checked all sources on Parallax that I could find)
CO2 sensor = ~160 mA (Sense Mode) / ~2 mA (Standby)
1302 Real time clock chip= less than ~300 nA ( If somebody could tell me what nA is? I think it was a typo on their part (This is all I could find that resembled mA)
3202 ADC= 550 µA
I would like someone to double check these due to the chance that they are wrong.
Dylan Landry
[noparse][[/noparse]Sylvie and Dr. Allen, what are your thoughts about Dylan's answer...? - Mark]
Somewhere... recently said that people shouldn't work with electronic parts until they know what they're doing... Having a robot that continuously reset itself was probably a great lesson about what kind of power supply you need.
Yes, it was a lesson learned the hard way. But it was·one of many lessons·learned. That's why we're thrilled to have experts like you and Tracy to guide us along. I hope the Rocketeers are learning a lot. That's what the project is all about.
Sylvie said, "I believe that you're powering the MAWD from its own 9V battery. Is that correct? If so, then you do not need to figure it into your current draw.
The MAWD has a separate power power supply so it isn't figured into the amperage calculations.
Sylvie said, The six devices I listed above are all Parallax products, and I believe that you can find the current draw for each in the product pages.. You should be able to find what you need, though you'll have to snoop around a bit in the documentation.
Rocketeers, Sylvie confirmed what I suggested. This is how you calculate how much amperage the ASP will draw (use) and what "size" of battery we will need.
===================
Sylvie, as we were walking down the street from campus to the Metro (subway stop), Christopher and I met Donald Rumsfeld and chatted with him for a short while. Welcome to Washington, DC, Christopher...!
Thanks for all your helpful input, Paul. We'll be cheering for the Orioles in a·little while·(and later, for "our favorite" soccer team... whichever that is!)
The 1302 Real time clock chip = less than ~300 nA... could somebody tell me what nA is? I think it was a typo on their part (This is all I could find that resembled mA)
Dylan,
·· Assuming that "nA" not a typo,·where else could you find the answer? What small·amount of measurement·could the letter "n" represent? Think of tiny, tiny, tiny...! You could "google" RTC ("Real Time Clock" chip) and read more. Or is it just a typo?
What could happen to the ASP (data, electronics, and our mission) if WE miscalculate...?
Good work Dylan. Now you're starting to think and work·like a scientist!
1) This website says that "their" RTC (Real Time Clock" chip) drawa 450 nA, not mA. So "nA" appears to be a correct unit of measurement:
"Drawing only 450nA (typical), the·[noparse][[/noparse]RTC] can accurately keep time for more than ten years on a 48mAh lithium coin cell." (HINT! HINT!)·
Will the RTC chip drain the power from our ASP battery...?
Go Orioles! Go Cote d'Ivoire "football" team (Mike, I·lived·in Cote d'Ivoire·twice. I actually saw their national team play in Abidjan, the capital city, and in Yamossoukro) Keep up the good work. I'm working on trying to find a way to get you to Nevada, too.
I have been searching for a little bit now. The only thing I can find is that Na (not nA) is the chemical symbol for sodium. Possibly it could be something along the lines of mA (micro-amp).. The only thing I can think of off the top of my head that is smaller then Micro is, nano? As in, nanotechnology? Nano-Amps. Is that why the post, "Less then"? To indicate that you really don't have to worry about it? I have a good feeling about this.
P.S Donald Rumsfeld was the Secretary of Defense for Bush's term.
Dylan Landry said...
I have been searching for a little bit now. The only thing I can find is that Na (not nA) is the chemical symbol for sodium. Possibly it could be something along the lines of mA (micro-amp).. The only thing I can think of off the top of my head that is smaller then Micro is, nano? As in, nanotechnology? Nano-Amps. Is that why the post, "Less then"? To indicate that you really don't have to worry about it? I have a good feeling about this.
P.S Donald Rumsfeld was the Secretary of Defense for Bush's term.
Yes, "n" = nano. Click on the last link I posted, and the first two links. There you will find your answer.
I have a good feeling about this, too. We're not talking about much amperage here at all (for the RTC chip anyway.)
Oh wow. I didn't even see those links. I think I wrote the reply before you posted the links and then posted mine after yours.
"I have a good feeling about this, too. We're not talking about much amperage here at all (for the RTC chip anyway.)" Could I ask you what you mean by that?
Does he mean that the RTC chip will only take up 0.00045 mA? Check my calculations, but on the second link Mr. Kibler posted (near the bottom) it says that 1 mA= 1,000,000 nA. Since the RTC chip only takes up 450 nA, that would be the same as 0.00045 mA.
Justin,
Yes, that would be the correct conversion. But according to the Parallax Documentation, it is only ~300 nA (.0003 mA). We only need the SHT sensor now but there is no reference to the amount of Amps needed. Just 30μW which is not AMPs. You cannot convert that I don't think but I could be wrong. I have checked conversion websites and Watts is not posted. If someone could help on this it would be greatly appreciated.
550 µA (micro amps) equals 0.55 mA (for the 3202 ADC). On the second link Mr. Kibler posted, it says that 1 micro amp equals 0.001 mA. If the 3202 uses 550 µA, then it uses 0.55 mA (0.001 x 550).
Justin,
Look 5 posts up. It has MOST of the mA needed except for the SHT11. We need to figure out how many amps the SHT11 needs. It doesn't post it on the documentation from Parallax so we need to figure where else we can find it.
Comments
How much power is it going to take to run all the electronics? We would need to find this out first before we can find out if the battery would be sufficent enough.
Justin
This seems important to note: PIN 3 and PIN 4 are not assigned or defined in·Andrew's "MAWDBOECO2_w_ADC_TEST -·June 21, 2010" program. The wires to these pins come from the CO2 sensor's ALR and CNTL/HSW
CNTL/HSW <---- goes to ---->· PIN 3 on the BOE
ALR··········<---- goes to ----> PIN 4 BOE
Though we haven't mentioned it much, PIN 15 is taken by the MAWD. It is defined in the program as "MAWDin".
Mark
·· Dylan asked the same question·just two hours·before you did (read his post to the forum):
1.) What is the total Amp drainage of the current ASP build?
2.) What is the combined Voltage requirement of the current ASP build?
3.) What are some Voltage limits of some of the components on the current ASP build?
My answer (posted below) was:
Dylan, you could look at the documentation sheets for each of the parts on the ASP. See what each requires for amperage and then do the math. For example, if the total amperage "draw" (usage) for all the parts happened to be 1000 mA, and if the battery is a 5000 mAH battery, then it should run the ASP-2 for 5 hours...
So the short answer is, read the documentation, see how much amperage each component uses, then do the math. This is homework for the Team. The specifications for our battery are posted below.
This is not a competition to see who can finish first but rather, an opportunity for the the Team to work together to solve·a problem.·Communicate and collaborate, Justin. "Talking with your lab partner IS allowed." Take a leadership role. Solve the problem together.
Mr. Kibler
The power consumption issue is complicated by the fact that some loads are not constant. For example, the USB datalogger uses more power (lots more) when it is writing data to the thumb drive than when it is just sitting there. How do you think you will account for a load that spends a percentages of time at different power hunger levels? Evaluate the parts first, then the whole ASP.
I recall that Phidippides had a dead man switch, a wood dowel in a socket, I think, that was pulled out to turn on power when the rocket separated at some point in its trajectory. Am I remembering correctly? And that is no longer the plan, huh? Now the ASP-2 will operate from ground to apogee to landing and after?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tracy Allen
www.emesystems.com
Mark, I am still puzzled by the readings you are reporting. It sounds like there may not be a good connection between the TP1, TP3 test points and channels 0 and 1 on the ADC. Maybe it is the soldering that needs to be done. It is too sensitive and it seems that the effect when you breath on it is not so much due to the CO2 sensor as it is to Murphy's law of vaporous condensation! It will be very useful to have a connection from TP3 over to the MCP3202; that will be a good reference for testing. You will know you have it right when you can adjust the calibration potentiometer from one end to the other and see the screen reading go from 0 to 2730 counts, (0.0 to 3.3 Volts).
I'm pretty much west coast now, as I have lived here since I was 17. My own dad was in government service and we moved around. I was born in Denver, but spent 3rd to 8th grade in Michigan, and 9th to 12th grade at McLean H.S. in Virginia just outside D.C, and finally to California. I spent my summer between HS junior and senior year in an electrical engineering program at the U. of Virginia at Charlottesville VA and at Ft. Mammoth NJ. I remember well teachers I had at that time, and projects with friends. A lot had to do with ham radio, and trying to listen in on the space program and other activities which shall not be fully reported although we managed to stay out of trouble! I appreciate what you are doing with the rocketeers with these exciting and constructive activities and am happy to help when I can.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tracy Allen
www.emesystems.com
·· Guys, because you don't have a complete ASP at home to work with, I think your best approach is to read the documentation for every one of the components, find out how much amperage each one uses, then add all the amperages together to get a total. It would be tough to measure actual amperage while the ASP is running because:
1) We would need 6 people and 12 hands to hold all the voltmeters needed to connect to every device on the ASP when it's running.
2) The amperage varies (changes) on each device when it runs. So I think it might be hard to record because it would read read "high", "low", "high", "low", etc... on each device.
3) Our actually "meeting·time" is severly limited so doing step #1 is not an option for weeks. And we only have two voltmeters...
I would look at the documentation and add all the "amperages required" together.
Dr. Allen believes that the battery we're using has plenty of power storage capability (see his comment directly below.) I agree, but let's prove it with math.
Andrew, please guide this discussion.
Good work~ Good morning (yawn),
Mr. Kibler
dylan landry wrote:
> Dear Mike,
> Test? You mearn like attach a voltimeter at certain TP to see ramaining
> voltage + mAH before and after to see the requirements?
>·
> (Last email, gotta snooze)
>·
> Dylan Landry
>
> On Tue, Jun 22, 2010 at 11:58 PM, Mike Prindiville ·wrote:
>>
>> Dylan, do you think we should test it?
>>
>> ________________________________
>> From: dylan landry
>>
>> Dear Project Team,
>> Mr. Kibler has recently assigned questions for us to fill out.
>> __________________________________________________________
>>
>> QUESTION: Will our battery be "dependable" enough for the mission we have
>> planned? Yes, or no? Defend your answer with facts and details, not vague
>> speculation or science fiction. If you're not certain, write a simple plan
>> explaining how we can/should find out.·
>> This question is quite challenging. We will need a lot of information to
>> answer it.
>> 1.) What is the total Amp drainage of the current ASP build?
>>
>> 2.) What is the combined Voltage requirement of the current ASP build?
>> I believe that if we combine all of the voltage requirements for the
>> current ASP build, we will get the answer to how much volts it needs. But I
>> have a feeling that I am dearly wrong on that one. Any help would be great.
>> But I am a little bit sure that if you do combine the mAH needed that you
>> will get your answer· to if it has enough mAH. Again, any help would be
>> great. First, we need to find out if what i just said is correct : ). Once
>> we get that cleared we can assign each other certain parts of the ASP, get
>> there requirements then have our answer.
>> Dylan Landry
We're using a 9.6 volt Ni-Cd battery because it was what we had available. Our budget, as always, is very limited. If we wanted to achieve a higher altitude-- and if we were building the rocket, too-- I would make everything much lighter, including the battery. Weight isn't a real consideration because the rocket motor is pretty powerful. Physical space is the most limiting factor.
I'm packing up the ASP until we get back to NH tomorrow afternoon. I have to retrieve Christopher from freshman orientation and (maybe) go to an Orioles game at Camden yard this evening. I'll be checking in regularly until we leave for NH.
Mark
·
"Dylan and others,
Thank you for reiterating these questions. While they may not seem important on the surface, they are in fact very mission critical. Mr. Kibler may remember when we added a large piezo buzzer to the NASA SLI robot, last minute. We only tested the robot on the ground for a couple of minutes, but never actually stress tested it. If we had, we would have learned that the robot, even with a brand new and fully charged 9v lithium battery, would only last (consistently) for just a few minutes. After the few short minutes of battery life, the battery dropped below the minimum amount of electricity required by the components, and the robot reset itself numerous times, which was evident in the data log when we analyzed it later {Mr. Kibler notes: This actually happened to the robot during our second trip to NASA...!}
As Dylan first suggested, you might consider taking a look at the electrical draw of each of the individual components and adding them up together. Then, you might consider looking at the specification sheet for the current battery (yes, they have them for batteries too) and interpreting whether or not it will suit our needs. More importantly, let's assume that the battery we have will not last long enough. Then what? Answer that, as well as the other questions below. Try to answer them independently and please show your methods and data, so it's easier to compare our solutions.
Thank you,
Andrew"
I have just hit a roadblock, what are all the components on the ASP anyways? Andrew, could you possibly get that, "Build List" that you where making to me. I, and i'm sure others, have no idea of what components are attached to the current ASP build.
Dylan Landry
Having a robot that continuously reset itself was probably a great lesson about what kind of power supply you need. I learned that a somewhat harder way, involving lots of smoke and the frying of two $19 boards. In retrospect, knowing what I know now, it was obvious, but I don't think I would have learned about being careful about total current draw without having made that mistake myself.
There are some other issues I still don't understand having to do with power supplies, including the ability of a supply to provide a certain amount of current quickly, which is a big issue for rocket motor and ejection charge igniters. I see people talk about the "internal resistance" of batteries when they explain that, but I don't yet understand it. I will.
An Orioles game sounds like a blast. Camden Yards is definitely on my list of stadiums to see.
Obviously I picked the wrong team in the World Cup. France completely melted down in an utterly graceless way. I cannot defend any of that.
Spain, on the other hand, seems to be resurgent, and I'm excited about that.
The US plays in about a half-hour.
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"Learn to obey before you command."
-Solon
Post Edited (Mike NH) : 6/23/2010 4:02:40 PM GMT
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"Learn to obey before you command."
-Solon
So you've got these devices to worry about powering:
BS2e (correct?)
USB Datalogger
SHT11 Humidity sensor
CO2 sensor
1302 Real time clock chip (correct?)
3202 ADC chip
I believe that you're powering the MAWD from its own 9V battery. Is that correct? If so, then you do not need to figure it into your current draw. If that's not right - if you're running it from the same battery and/or power supply, then you have to figure it as well.
The six devices I listed above are all Parallax products, and I believe that you can find the current draw for each in the product pages. I just looked up the Memory Stick Datalogger, and it's there. So are both sensors, and the RTC chip. You should be able to find what you need, though you'll have to snoop around a bit in the documentation.
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I see that both the US and England won, and have advanced to the round of 16. Still have my fingers crossed for Spain.
Post Edited (sylvie369) : 6/23/2010 4:36:02 PM GMT
I may be mistaken, but didn't the ASP also record TEMP?
Dylan,
The SHT11 is both a temperature/humidity sensor.
Andrew
Sylvie,
You've got everything listed correctly. We can plan on using a BS2e, not a BS2, and I already have one installed in my ASP-2 mockup. As you said, the MAWD is powered by it's own battery. I'll dig up all those data sheets later, and see what I can find. Team members -- please do the same, as we have been discussing via e-mail recently.
Andrew
I think that when you look at the current draws of these various devices, you will learn something very interesting. It's an excellent exercise. I sure wish someone had put me through this when I was your age (I believe we had electricity at the time. I know fire had already been invented).
The SHT11 is also known as the Sensirion Temperature/Humidity Sensor correct? I believe I found the correct one on Parallax but I am not entirely sure. Here is the link to the Sensirion Temperature/Humidity Sensor.
http://www.parallax.com/StoreSearchResults/tabid/768/List/0/SortField/4/ProductID/94/Default.aspx?txtSearch=SHT+11
Tracy,
If you read the first paragraph of the description, you are mentioned and so is your website. I just thought that was kind of interesting.
Sean
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"Learn to obey before you command."
-Solon
· Good work! THIS is what we're looking for to determine how much amperage the ASP will use. This is what you need to know to calculate the answer to the question, "How big of a battery (how much amperage) will the ASP need? Our battery is a 5000 mAH (milli-amp-hour) battery. That means the ASP could use 5,000 mA for one hour, 2,500 mAH for 2 hours (2,500 x 2), 1,666 mA for 3 hours (1,666 x 3), 1,250 mA for 4 hours, etc.
·
On Wed, Jun 23, 2010 at 2:14 PM, dylan landry wrote:
Dear Project Team,
·· Ive gotten the mAH count for all the components, but I have had trouble reading the BS2e data sheet. Apparently, it is 30 mAH per PIN input/output. I am not sure if I am reading this correctly but that is what I got.
mA requirements of each component:
BS2e= 30 mAH per PIN input/output
Datalogger, Standby= 2mA, running= 25mA
SHT11 = N/A (Checked all sources on Parallax that I could find)
CO2 sensor = ~160 mA (Sense Mode) / ~2 mA (Standby)
1302 Real time clock chip= less than ~300 nA ( If somebody could tell me what nA is? I think it was a typo on their part (This is all I could find that resembled mA)
3202 ADC= 550 µA
I would like someone to double check these due to the chance that they are wrong.
Dylan Landry
[noparse][[/noparse]Sylvie and Dr. Allen, what are your thoughts about Dylan's answer...? - Mark]
Sylvie said, "I believe that you're powering the MAWD from its own 9V battery. Is that correct? If so, then you do not need to figure it into your current draw.
The MAWD has a separate power power supply so it isn't figured into the amperage calculations.
Sylvie said, The six devices I listed above are all Parallax products, and I believe that you can find the current draw for each in the product pages.. You should be able to find what you need, though you'll have to snoop around a bit in the documentation.
Rocketeers, Sylvie confirmed what I suggested. This is how you calculate how much amperage the ASP will draw (use) and what "size" of battery we will need.
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Sylvie, as we were walking down the street from campus to the Metro (subway stop), Christopher and I met Donald Rumsfeld and chatted with him for a short while. Welcome to Washington, DC, Christopher...!
Thanks for all your helpful input, Paul. We'll be cheering for the Orioles in a·little while·(and later, for "our favorite" soccer team... whichever that is!)
Mark
·· Assuming that "nA" not a typo,·where else could you find the answer? What small·amount of measurement·could the letter "n" represent? Think of tiny, tiny, tiny...! You could "google" RTC ("Real Time Clock" chip) and read more. Or is it just a typo?
What could happen to the ASP (data, electronics, and our mission) if WE miscalculate...?
Good work Dylan. Now you're starting to think and work·like a scientist!
PS - Who is Donald Rumsfeld anyway...?
Mr. Kibler
1) This website says that "their" RTC (Real Time Clock" chip) drawa 450 nA, not mA. So "nA" appears to be a correct unit of measurement:
"Drawing only 450nA (typical), the·[noparse][[/noparse]RTC] can accurately keep time for more than ten years on a 48mAh lithium coin cell." (HINT! HINT!)·
http://www.futurlec.com/News/ST/Clock_Chip.shtml
2) Or you could look at this website:
http://theknowledgeworld.com/world-of-aerospace/Convert-Ampere-pA-nA-uA-mA-A.htm
3) Or this one:
http://en.wiktionary.org/wiki/nanoamp
C'mon guys, do you homework:
What IS a "nA"?
Will the RTC chip drain the power from our ASP battery...?
Go Orioles! Go Cote d'Ivoire "football" team (Mike, I·lived·in Cote d'Ivoire·twice. I actually saw their national team play in Abidjan, the capital city, and in Yamossoukro) Keep up the good work. I'm working on trying to find a way to get you to Nevada, too.
Mr. Kibler
P.S Donald Rumsfeld was the Secretary of Defense for Bush's term.
I have a good feeling about this, too. We're not talking about much amperage here at all (for the RTC chip anyway.)
"I have a good feeling about this, too. We're not talking about much amperage here at all (for the RTC chip anyway.)" Could I ask you what you mean by that?
Does he mean that the RTC chip will only take up 0.00045 mA? Check my calculations, but on the second link Mr. Kibler posted (near the bottom) it says that 1 mA= 1,000,000 nA. Since the RTC chip only takes up 450 nA, that would be the same as 0.00045 mA.
Yes, that would be the correct conversion. But according to the Parallax Documentation, it is only ~300 nA (.0003 mA). We only need the SHT sensor now but there is no reference to the amount of Amps needed. Just 30μW which is not AMPs. You cannot convert that I don't think but I could be wrong. I have checked conversion websites and Watts is not posted. If someone could help on this it would be greatly appreciated.
550 µA (micro amps) equals 0.55 mA (for the 3202 ADC). On the second link Mr. Kibler posted, it says that 1 micro amp equals 0.001 mA. If the 3202 uses 550 µA, then it uses 0.55 mA (0.001 x 550).
Look 5 posts up. It has MOST of the mA needed except for the SHT11. We need to figure out how many amps the SHT11 needs. It doesn't post it on the documentation from Parallax so we need to figure where else we can find it.