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4-channel TC meter and datalogger project
JETROASTER
Top  #151 Print Post
Posted on 06/14/2010 3:43 PM

Quote

JimG wrote:
Would like potential users of this board to answer a question:

Should the supply for OT1 and OT2 be taken from the raw, unregulated Vin pin, or from the regulated 5V pin? At present, they are supplied from the regulated 5V pin. But I am leaning heavily towards making the change to Vin.

Opinions?

Quote

milowebailey wrote:
I'd be interested in a couple of these boards if there is a group buy

At present, goldphoenix.com seems to offer the best combination of price and production schedule.

For ~$90, it looks like they will build 25 boards in 5 business days. That is only 20 boards more than we need :-)

Also checked 4pcb.com. Better turnaround time (1 business day). Five boards would run ~$95 for their bare bones option. But there is no silkscreen offered at that price, and I see that as significant problem.

Jim
 
JETROASTER
Top  #152 Print Post
Posted on 06/14/2010 3:50 PM
I guess for the same money, I'd take 2 boards.
...I'm bound to screw one up.
As far as which pins where???....completely clueless. Sorry.
-Scott
 
bvwelch
Top  #153 Print Post
Posted on 06/14/2010 4:33 PM
To clarify - the $90 Jim is referring to the manufacturing cost of a run of 25 bare PCB boards - they will need parts and assembly before they are useful, and you'll need an Arduino board of course.

I'm in for a couple of the bare PCB also. And if someone wants their board assembled and tested, we can work that out too.

Cool!
Edited by bvwelch on 06/14/2010 4:34 PM
 
JimG
Top  #154 Print Post
Posted on 06/14/2010 5:01 PM
Order placed with goldphoenix.

Links to as-ordered bare PCB:

http://www.mlgp-l...06-brd.pdf
http://www.mlgp-l...06-sch.pdf
http://www.mlgp-l...r-0106.zip (gerbers)
http://www.mlgp-l...r-0106.brd
http://www.mlgp-l...r-0106.sch

Jim
Edited by JimG on 06/14/2010 5:02 PM
 
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allenb
Top  #155 Print Post
Posted on 06/14/2010 7:12 PM

Quote

freshbeans wrote:

Quote

JimG wrote:
Would like potential users of this board to answer a question:

Should the supply for OT1 and OT2 be taken from the raw, unregulated Vin pin, or from the regulated 5V pin? At present, they are supplied from the regulated 5V pin. But I am leaning heavily towards making the change to Vin.

Opinions?

Quote

milowebailey wrote:
I'd be interested in a couple of these boards if there is a group buy

At present, goldphoenix.com seems to offer the best combination of price and production schedule.

For ~$90, it looks like they will build 25 boards in 5 business days. That is only 20 boards more than we need :-)

Also checked 4pcb.com. Better turnaround time (1 business day). Five boards would run ~$95 for their bare bones option. But there is no silkscreen offered at that price, and I see that as significant problem.

Jim


I'm assuming OT1 and 2 are PWM to SSR's which, in my experience don't need anything special to pulse them.

Count me in for one board.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
randytsuch
Top  #156 Print Post
Posted on 06/14/2010 7:19 PM
I'll go for at least one board, maybe 2.

I think adding the circuit to drive a couple SSR's is cool, since my end goal is to use this to replace my PID.

I'm wondering if you could use the 2nd SSR output to control fan speed. Would need to switch pretty fast. I was considering another circuit to do it, but since this is "free", I will play with it, and see what I can do.

Thanks for all the work, Bill and Jim.

Randy
 
JimG
Top  #157 Print Post
Posted on 06/14/2010 7:24 PM

Quote

allenb wrote:
I'm assuming OT1 and 2 are PWM to SSR's which, in my experience don't need anything special to pulse them.

Yup, that's what they are. I ended up supplying them from Vin on the theory that this would better protect the Arduino against unwelcome events on the output pins.

Jim
 
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milowebailey
Top  #158 Print Post
Posted on 06/14/2010 11:31 PM
I'll take 5 boards... I'm sure I'll trash one or two with surface mounts..

Let me know how/when you need cash.

I have 3 arduino's laying around here somewhere.....

Thanks for doing this. Great to see others excited about the possibilites of the arduino.
 
JETROASTER
Top  #159 Print Post
Posted on 06/15/2010 6:55 AM
I'd take 2. One would need to be assembled and tested.

Let me know the whens and hows. Thanks-Scott
 
farmroast
Top  #160 Print Post
Posted on 06/16/2010 10:42 PM
Could someone summarize the basic capabilities etc. of this latest unit. :|

thanks
Ed B.
DreamRoast 1kg roaster, Levers, Hand Mills http://coffee-roa...gspot.com/
 
JimG
Top  #161 Print Post
Posted on 06/16/2010 11:26 PM

Quote

farmroast wrote:
Could someone summarize the basic capabilities etc. of this latest unit.

First, we must assume the hardware will work as intended Shock

When stacked on an Arduino Duemilanove (or compatible), the board will be capable of reading 4 analog inputs between -2 and +2 volts. They don't necessarily have to be thermocouples, but this is the intent.

It will allow the optional grounding of the thermocouples using jumpers on the board, in case that becomes necessary for correct operation. With the jumpers open, the TC input will float.

It will have two DC outputs that are intended for driving external SSR's using pulse width modulation (PWM).

What can be done with these inputs and outputs then depends on software.

With appropriate programming (and external LCD display), the board could be a standalone roast monitor, showing temperature readings from 4 sensors. It could also be programmed to provide real time rise rates.

It could also be used as a roast monitor and logger while connected via USB to a PC.

Since it has a couple of DC outputs, with the right programming it could also be used to build a PID controller.

Bill is a pro on the software side, so I'm anxious to see what he develops once we have the first generation PCB's in hand.

Jim
 
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bvwelch
Top  #162 Print Post
Posted on 06/17/2010 2:41 AM
I'm not sure that any of my co-workers would call me a 'pro' but I have written a lot of software over the years. At least nowadays I've got better tasting coffee :-)

Since the prototype hardware is already working, I am confident Jim's printed circuit board will also. If not, Jim correct any errors and try again. :-)

One thing I didn't test yet, but should work, is the 4-20mA loop type sensors.
 
bvwelch
Top  #163 Print Post
Posted on 06/18/2010 7:03 AM
I tried to ask over on coffeesnobs about using their software on our project -- instead of a reply, I have been kicked off their forum with no explanation??? And my post has been removed. I don't recall my exact wording, but obviously it was misunderstood. I don't even know who to contact to explain.
 
JETROASTER
Top  #164 Print Post
Posted on 06/18/2010 8:21 AM
So....I will avoid any comments on 'open-source' if I go there. Yikes!
 
endlesscycles
Top  #165 Print Post
Posted on 06/18/2010 10:23 AM
The most valuable application to me is to write, save, and then "play" profiles. I see multiple inputs as a curiosity, but I'm convinced that bean temp is the only thing that matters as roaster design constraints solve for other variables.

It would be cool to automatically optimize the environment for heat transfer efficiency, and I can see that as a possibility, but that's complex.
-Marshall Hance
Asheville, NC
 
bvwelch
Top  #166 Print Post
Posted on 06/18/2010 10:44 AM
Marshall, that's a good summary but 'playing' a profile may not be so easy as it sounds.

A first step might be an overlaid graphic where the 'pattern' profile is displayed as a background (however many inputs you recorded previously), and the 'live' or 'real-time' values are displayed on top, and it is up to you, the human operator -- er -- artisan -- to re-create the same profile by whatever knobs/controls you have.

After you are able to do this consistently, we will be better positioned to automate the process. -bill
 
bvwelch
Top  #167 Print Post
Posted on 06/18/2010 10:48 AM
Just to clarify - I only asked the coffeesnobs about their PC software, because some of you expressed an interest. We already have PC software that works - displays a graph and saves to CSV files. It can be enhanced as we go along, or abandoned if someone provides something better or different.
 
endlesscycles
Top  #168 Print Post
Posted on 06/18/2010 3:58 PM

Quote

bvwelch wrote:
Marshall, that's a good summary but 'playing' a profile may not be so easy as it sounds.

A first step might be an overlaid graphic where the 'pattern' profile is displayed as a background (however many inputs you recorded previously), and the 'live' or 'real-time' values are displayed on top, and it is up to you, the human operator -- er -- artisan -- to re-create the same profile by whatever knobs/controls you have.

After you are able to do this consistently, we will be better positioned to automate the process. -bill


I'm already manually opperating at 20sec intervals to good effect. What I need is a controller with a clock that reads if the present temperature is higher or lower than the intended temperature as saved as a .csv, on one second intervals. No PID computation needed, just on or off. Randy G has a link to such a device, though 10min capacity. It is $65....a little steep, but still less than a PID. The 10min limitation is not ideal, though.
-Marshall Hance
Asheville, NC
 
bvwelch
Top  #169 Print Post
Posted on 06/18/2010 5:01 PM
Our gadget can do what you're asking for, no time limit -- it's only software.

I don't know exact parts cost yet, and some one will need to assemble the unit.

The software may cost you a taste of some of this home roast you're bragging about. :-)
 
endlesscycles
Top  #170 Print Post
Posted on 06/18/2010 5:29 PM
I've got lots of amazing coffee, green and roasted!

Here's the toy: http://www.thesil...;Itemid=57

And it's book: http://www.thesil...reflow.pdf
-Marshall Hance
Asheville, NC
 
bvwelch
Top  #171 Print Post
Posted on 06/18/2010 7:34 PM
Yeah, we talked about that gadget previously in this thread - frankly it looks good, and priced cheap. There is a good chance we could re-program it too - that is the sort of cpu chip I use in my day-job doing embedded programming. But they are mighty proud of their lcd display.
Edited by bvwelch on 06/18/2010 7:36 PM
 
farmroast
Top  #172 Print Post
Posted on 06/19/2010 10:54 AM

Quote

bvwelch wrote:
I tried to ask over on coffeesnobs about using their software on our project -- instead of a reply, I have been kicked off their forum with no explanation??? And my post has been removed. I don't recall my exact wording, but obviously it was misunderstood. I don't even know who to contact to explain.

andy@coffeesnobs.com.au Andy Freeman
Ed B.
DreamRoast 1kg roaster, Levers, Hand Mills http://coffee-roa...gspot.com/
 
JimG
Top  #173 Print Post
Posted on 06/20/2010 10:17 PM
With Bill's assistance and guidance, I am making progress on a few software fronts.

1) There is now an open source pulse width modulation (PWM) library available that uses 16-bit Timer1 on the Arduino. This library supports the longer cycle times I like to use for PWM control of heaters. The default Arduino PWM system runs at 490Hz with a resolution of 255 (it is an 8-bit timer).

The new library supports cycle times from 128Hz to 4 seconds, with much higher resolution.

2) There is now an open source type K thermocouple linearization library. It is based on the ITS-90 standard and is "exact" to within reasonable limits. This library can be used to replace/improve the approximation of 40.69uV per degree C that Bill's first logger program uses (turns out that really isn't a bad approximation at roasting temps). I've tested the new library using one of Bill's prototype boards and a thermocouple calibrator. Very close agreement.

3). Some improvements have been made to the ambient temperature sensing code. We've gone from 9 bits to 11 bits on the MCP9800 config. And have added code to do some smoothing of the ambient temp readings (they should vary only very slowly, so quick changes are probably noise). Better ambient temp sensing is giving steadier and more accurate thermocouple readings on the bench.

There is an open source archive for this new code here:

http://code.googl...loads/list

I've not received a ship notification from Goldphoenix on the PCB's yet, but I hope they'll have them to Fedex some time this week. Once they arrive here, I'll put one together to be sure there aren't any bonehead errors on the boards, then distribute them to whoever who asks, or has already signed up. I'll propose to split the actual costs ($92) depending on the number of boards that get distributed. It will probably run between $4 and $10 per board, plus mailing costs.

I'm not going to offer to assemble finished boards, but I think Bill might be planning to offer his services?

Jim
 
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JimG
Top  #174 Print Post
Posted on 06/24/2010 9:32 PM
4-channel TC input PCB's are here. I've assembled and tested one, and all seems to be OK. All 4 inputs are working, as well as both DC pulse outputs. Even better, it stacks on the Arduino Duemilanove just like it's supposed to.

I'll get some pictures posted soon.

Jim

Pictures:

www.mlgp-llc.com/arduino/public/P1000736small.jpg
www.mlgp-llc.com/arduino/public/P1000735small.jpg
Edited by seedlings on 08/30/2010 3:22 PM
 
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bvwelch
Top  #175 Print Post
Posted on 06/24/2010 9:58 PM
Very cool! Good photos too!

There are only two SMT parts on the board - not hard to solder. I can help but I'm pretty sloppy at soldering and I am pretty slow at it too. Anyone else want to jump in and help with soldering, making parts lists, or maybe putting together a little kit of parts?

I've been roasting all week using a prototype version and tinkering my PC logging software. Our meter's data format is open-source, so maybe some other guys will want to get their software working with our meter. Until then, I've got something going that will log to a CSV file and also displays a target 'profile' on-screen and a rudimentary method of making notes during the roast.

I'll also get back to working on the hand-held rise-o-meter too. I have a prototype but will welcome feedback on how to improve it.
Edited by bvwelch on 06/24/2010 10:03 PM
 
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