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Topic: Open Source Data Logger Project Using the Arduino? (Read 37 times) previous topic - next topic

rcottiss

I have a need for a data acquisition solution and I would be interested to know if it would fit into the scope of this data logger project.

I have a Wood Fired Brick Oven that I built in my back yard. It has several K Type Thermocouples (5 but other ovens could have up to 8) embedded in the mass to measure the temperature of the oven as it heats over several hours. I connected these thermocouples to my PC via a TC-08 Thermocouple Logger from PicoTech (See:http://www.picotech.com/thermocouple.html - I bought the older serial version) and ran a serial cable into the house ( about 50ft). This worked for a while but I the elements got to the logger and it stopped working. The latest version is USB and it's $500 without wireless capabilities. For a replacement I was thinking about a wireless version using Arduino and the XBee shield. To get 8 channels I guess it needs an multiplexer (or is it a demultiplexer?) module, and possibly a thermocouple A/D converter chip, to poll the thermocouples and communicate to the PC.

This real world example seems to highlight some of the common issues with data acquisition/logging applications:
  • Harsh Environments a the point of acquisition
  • Remoteness of the data acquisition point
  • Real Time data is required. In this case it needs to log the data to a real-time display. Logging to a local data store is not an option
  • Data visualization. It needs a software component to graph the results.


Another logging application I have in mind for Arduino is a GPS logger to geotag digital photos. This would involve logging time and location to a data store (SD for example) and then combining that information with   the digital photos based on the timestamp on the photo.

If anyone is interested in a collaborative project for either of these applications. I would be interested. I do not think it needs a competition if there are members of the community that have a common goal. I see advantages for everyone by working on these types of applications under a common data logger/acquisition project. The results could be more modular.

Thanks, Robin

kg4wsv

Maxim makes an SPI interfaced K type thermocouple interface, complete with reference junction, amplifier,  ADC, etc.  The Arduino can easily handle 8 of them via SPI.  The arduino can also drive an LCD or LED display.

Bluetooth is another wireless option.  The advantage over zigbee is that your computer may already have bluetooth.  can't remember the max range off the to of my head, though...

-j


agent_orange

I did a bit of work on this and got an SD card working (reading/writing) no problem which makes it very easy (and cheap!) to store large amounts of data. Using even a small SD card u could capture data at reasonably high sample rates for a long time. I also added a max1307 real time clock to add timestamps. I did a bit of work on an arduino shield for the circuit with all of this on it but haven't sent it off yet.

To get 8 channels I guess it needs an multiplexer
You can add an 4051 which will give you 8 channels on one analog input and use 3 digital lines.

Real Time data is required/Data visualization
This is actually easier than storing it in a storage device. Just write the results you get to serial. On the pc side read them in and graph them (processing can do this) other options could be python or VBA. There is also a few programs around to do this. A quick google found this one http://www.live-graph.org/



I'll post up my circuits and code once I have it working ok and everything is cleaned up and its not too embarrassing   :P  

follower

#13
Feb 07, 2008, 02:49 pm Last Edit: Feb 07, 2008, 02:50 pm by follower Reason: 1
Quote
everything is cleaned up and its not too embarrassing

I would like to start a campaign on these forums for people to start releasing code when it's still at the "embarassing" stage. The number of times a thread ends with a post saying "I'll release it when it's tidied/not embarrassing/perfect" and no further code seems disturbingly high.

Embrace your code's imperfections in the face of its utility, release now!

In a month's time untidy, embarrassing code is still going to be a lot more useful to others than no code--it also probably won't impact your future employment/dating opportunities too much. :-)

--Phil.

P.S. This isn't aimed specifically at you, this thread just happened to be active as the thought occurred to me. :-)

blalor

Quote
Quote
everything is cleaned up and its not too embarrassing

I would like to start a campaign on these forums for people to start releasing code when it's still at the "embarassing" stage. The number of times a thread ends with a post saying "I'll release it when it's tidied/not embarrassing/perfect" and no further code seems disturbingly high.

Embrace your code's imperfections in the face of its utility, release now!

In a month's time untidy, embarrassing code is still going to be a lot more useful to others than no code--it also probably won't impact your future employment/dating opportunities too much. :-)

I agree!  I think few of us are real professionals here and we're all here to learn, even a brain dump of imperfect information thrown back into the cloud is better than nothing at all, and we can all benefit from dissecting and optimizing what you've got so far.  :)

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