I need a Geek

Comments

• Jon Williams Posts: 6,491

  2004-10-14 19:07 edited 2004-10-14 19:07

  If you post your requirements, I'm sure you'll get lots of help from the members of this forum.
  
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  Jon Williams
  Applications Engineer, Parallax
  Dallas Office
• KERBS Posts: 26

  2004-10-15 17:15 edited 2004-10-15 17:15

  Thank you, I'll do that
• KERBS Posts: 26

  2004-10-15 17:31 edited 2004-10-15 17:31

  I would like to input 2 pulse signals from hall effect sensors. 1 sensing rotation of the tire and 1 sensing the rotation of the shaft applying the fertilizer. with these 2 rate values, and a opererator entered constants for application width, cu'/revolution and lb/cu' I will be able to display live application rate exprssed in lb/acre. Ideally the end product would have a means of entering and storing the calibration constants in the field. With the information above supplied to the monitor, I will be able to display the following: ground speed, acres covered, current lb/min flow, current lb/ace application rate. there should be some kind of selector that will enable the operator to select what is viewed on the lcd display. this system will enable the user to manually adjust his operating variables to his desired application rate.
• Bean Posts: 8,129

  2004-10-15 17:55 edited 2004-10-15 17:55

  Sounds like an interesting project.
  A question though:
  
  How are you planning to measure the lb's of the fertilizer ? Or do you know the lbs per shaft rotation ?
  
  That is definately a do-able project.
  
  Terry
• KERBS Posts: 26

  2004-10-15 21:24 edited 2004-10-15 21:24

  CU' PER SHAFT REVOLUTION WILL BE USER ENTERED AS A CALIBRATION CONSTANT
  LB/CU' MATERIAL DENSITY WILL BE MEASURED IN THE FIELD AND ENTERED AS AN OTHER USER ENTERED CONSTANT
  
  Post Edited (KERBS) : 10/18/2004 3:29:26 PM GMT
• stamptrol Posts: 1,731

  2004-10-16 12:12 edited 2004-10-16 12:12

  · Good morning,
  
  ····· I've done a a project like this for a specialist in "precision farming". The plan is to not over-seed and then to not over-fertilize.
  
  ···· Our system did all the measurements, as you described, and also logged the GPS coordinates every few meters as the tractor moved down the field. As well, it did real-time soil analysis so that it compensated for variations in soil conditions and adjusted the fertilizer application rate. No sense fertilizing a part of the field if it doesn't need it! Then, that data could be plotted, studied, etc, etc.
  
  ··· Whole system ran on a BS2sx with a bit of extra memory, LCD screen and some extra inputs and outputs.
  
  ··· Not a trivial project, but easily within the capabilities of the Stamp families.
  
  ··· Contact me off-forum if you want to discuss. If nothing else you may want to talk to the researcher.
  
  ···· sisk1404@nb.sympatico.ca
  
  · Cheers,
  
  ·· Tom Sisk
  
  
  
  ···
• KERBS Posts: 26

  2004-10-17 21:41 edited 2004-10-17 21:41

  Thanks Tom,
  And thank you all, for all the interest. You have all been very kind. I really have high hopes now, that this can really be accomplished
• KERBS Posts: 26

  2004-10-19 15:05 edited 2004-10-19 15:05

  can the basic stamp count in the back ground? or can I get another IC to handle this?
• Jon Williams Posts: 6,491

  2004-10-19 23:27 edited 2004-10-19 23:27

  The BASIC Stamp is single threaded; no background tasks.
  
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  Jon Williams
  Applications Engineer, Parallax
  Dallas Office
• KERBS Posts: 26

  2004-10-20 16:22 edited 2004-10-20 16:22

  As regards the total count functions of this monitor, ie. accumulated acres and distance, ( from wheel sensor pulses), and accumulated material applied ( from shaft sensor pulses); if I understand correctly, I need to have a seperate counter collecting accumulated pulses, and then have my basic stamp poll the "pulse accumulator". Does this sound right? If so, do I poll the "pulse accumulator" each time through the basic stamp program loop, or do i do it on some sort of time basis? Also, how do I handle the umdated pulse total? do I have the basic stamp zero out "pulse accumulator" and then add new pulses to the previous total on the stamp, or do I let the pulses continue to accumulate on the "pulse accumulator" and poll the continuously accumulating total from it? if it matters, I would predict that the pulses frequency will be around 2/sec. there may be a situation in the future if I use a flow meter instead of a shaft sensor, that the pulse frequency would be up to 300/sec. in this range is there any thing I should be concerned about?
  thanks again
• Jon Williams Posts: 6,491

  2004-10-20 17:02 edited 2004-10-20 17:02

  We have a device called the PWMPAL that may be useful in your application. It fits under a BS2 module and has multiple pulse inputs -- inputs that can easily handle your requirements. It's PWM output capability may of some use as well. Communication with the PWMPAL is serial via P0.
  
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  Jon Williams
  Applications Engineer, Parallax
  Dallas Office
• KERBS Posts: 26

  2004-10-22 16:47 edited 2004-10-22 16:47

  Do i communicate with the lcd serial or paralel?
• Jon Williams Posts: 6,491

  2004-10-22 18:24 edited 2004-10-22 18:24

  You can do either -- your choice.
  
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  Jon Williams
  Applications Engineer, Parallax
  Dallas Office
• KERBS Posts: 26

  2004-10-22 22:12 edited 2004-10-22 22:12

  OK,· Here is what my plan is to this point.· I will use a 8 or 16 bit counter to accumulate pulses from both sensors, these I will poll periodicly to produce readings for· distance traveled, total acres applied, total revolutions, total product applied.· I will use the count command on the bs2 to read pulse rates (frequency) to produce readings for aplication rate ( lb/ minute) and speed ( miles/ hr). The basic stamp will perform calculations based on these numbers and output to an LCD the desired information in useful units.
  ···· To this end I have collected these Items·· cp82c54·with 3 independant 16 bit counter, ·74LS590 8 bit counter, 74HC165 Parallel in/Serial out interface chip, and a 44780 LCD.·· Now, can any one help me from here.· Do I need a to use the 16 bit counter, or will the 8 bit unit work for me.·· And Since the 16 bit counter has 3 independant counters, can I use it for counting both signals from the 2 sensors?· And once I get this assembled, how the heck do I write the code??· AAAAAAAAAAAAAH
  ·
• Bean Posts: 8,129

  2004-10-23 03:33 edited 2004-10-23 03:33

  Kerbs,
  If it was easy someone else would have done it already.
  
  Terry
• KERBS Posts: 26

  2004-10-29 13:30 edited 2004-10-29 13:30

  Any Suggestions for collecting and calculating for pulse frequency when pulses are comming in at 1 per 3 sec?
• Bean Posts: 8,129

  2004-10-29 13:58 edited 2004-10-29 13:58

  If the pulses are 1 every 3 seconds the BS2 can easily count them by itself (with proper programming).
  
  Bean.
• KERBS Posts: 26

  2004-10-31 19:36 edited 2004-10-31 19:36

  I was asking hose this would be done. Specificly
• Harry W. Lewis Posts: 13

  2004-11-25 05:46 edited 2004-11-25 05:46

  Counting pulses that come once every 3 seconds is somewhere between easy and impossible for a Stamp.
  
  If the pulse input is on for 1/2 the time, you just have to look at the signal more often than once per 1.5 seconds to count the pulses. Easy!
  
  If the pulse is only on for 1 microsecond every 3 seconds, the Stamp can't do it without hardware help. i.e. Impossible.
  
  What kind of signal does your sensor put out?
  
  Also, while the Stamp is single threaded, if you have an external timer you can easily run multiple threads if the job is slow enough. Our Co-Processor has timers that let you do it. Your job sounds like it might be slow enough. Coding for multi-threaded robotics applications are on my website. ( www.bluebelldesign.com )
  
  Blue Bell Design Inc. is also a commercial electronic product developer using BASIC Stamps so, if you are interested in hiring a consultant, our services are available to help.
  
  Harry
  Stamp Robotics to the next level
  www.bluebelldesign.com
  
  Blue Bell Design Inc. - Makes Co-Processors, Co-Processors PCB and kits for Stamp applications. There is also a Tech Center section with lots of technical information for beginners to more advanced Stamp users.