Category Archives: Arduino

Pretty on the outside and ugly on the inside prototype

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So I’ve been busy doing a bunch of computer maintenance and looking into other things I’ve neglected while building the roaster so it’s been a bit slow.  I decided I wanted to start gluing corners together and drilling some holes to see how the case goes together so I can eventually get back to fixing the issues with the roast controller case.  Over the past several weeks I soldered together all of the boards, made wiring harnesses and figured out a bunch of “oops” moves I had made designing things when I got rushed for time.

Turns out I was not able to get stand offs locally in the sizes I had wanted so the heights are all screwed up where I placed holes on the outside surfaces.  I also forgot to specifically allocate power for the exhaust fan in the original design BUT I did have “Spare” pins allocated. The fan I ordered also was not the right size for the hole template I had used (Inside fan dimension vs outside screw / case dimension)… neither of them were actually labeled right the way every other fan I have is sized.

So with everything screwed or harnessed in place this is what I have for the Arduino…

The Arduino wired for Coffee Roaster control

It is a MEGA2560 mounted on a Crib for Arduino.  On top is an Ethernet Shield w/ microSD slot.  Then I used a variety of crimped headers to connect to some of the pins on the MEGA and on the ethernet shield.  I have twenty five lines in the bundle going to the Arduino.  I had some spare 10 strand cables from a project at Halloween and no 25 strand cables to use so I used one of those cable wraps to keep the all together after connecting DB25 to one end and header pins to the other.  Once the lid for the crib for Arduino is in place it then connects to the back of the enclosure.

Wiring Harness connecting to the back of the controller enclosure

As you may notice the sockets I was using for connecting the power out are the type that snap in.  The majority of these will not snap into most laser cut plastic sheets and instead are designed for aluminum cases.  The plug to the right on the other hand screws in.  These work great with a variety of thicker locations.  The fan was originally going to be on the inside with a wire cover on the outside but with the wrong size fan hole in use I had the wrong cover to fit the fans that I had that would fit the hole.

For the DB25 connectors it turned out good that I had decided to use a cut out pattern  that had the holes on the side for the anchoring hex nuts rather than just having them cut out so that I could mount them to the socket and anchor the connector.  Since the stand offs were too short they don’t allow me to anchor the PCBs to the bottom plate.  Instead I had to screw them to the back plate using normal screws and with the burnt circles on the laser cut work I had to use some washers too to keep it sturdy.  This is what the back plate looks like.

Rear Panel of controller

This panel includes – One non-filtered switched 15Amp Power Entry module, 2 snap in 15 amp convenience plugs, 1 5VDC fan, 2 DB-25.  The left one is the main guts for the LCD, TRIAC control, potentiometers, thermocouple, and a variety of other sensors.  The right includes all the non-essential stuff for backlighting all the buttons on the button pad and a few other things including spare wiring.  You cna see just a screw on the right since it was relatively intact and so it won’t block the DB25 plug being used.  The right DB25 has washers and screws in place.  These are primarily used to attached the PCB in place attached to the back side.

Next up is the inside view of the electronics area:

Rear View of the Back Panel

Rear view of the back panel.  I need to shrink up the crimp connectors around the wire  (they shrink like heat shrink tubing but is actually much firmer).  Also the connector on the right side (the switched power entry module) should have the screws more securely fastened with nuts and washers but this is mainly just a test to ensure it all fits together and then allow me to focus on some programming for a while to see if I can get more working and develop menus etc.  The clear acrylic bar is used to anchor the corners better.  I need to change the locations of the screws since I could not find screws the size I wanted without spending way too much for large quantities of them on the internet and having them shipped to me etc.  The thermocouple board on the right had the same issue with the stand offs so it is just floating loose in there right now.  I need to find somewhere to get the Omron thermocouple sockets where I dont need to order them by the 1000s since it looks like Ryan McLaughlin has stopped selling things on his site when they (used to) have problems getting the newer MAXIM thermocouple chip.  They’re all over the place now but he hasn’t restarted his store up so I don’t know the deal there.

Here is the view down into the enclosure from above:

Top view into enclosure

With the cover on:

Front panel installed on enclosure

Front panel running

Front Panel Running

When I send it back out again for a new case I hope to have a different board to install that will be switching the smaller breakout boards being designed onto the circuit board as well as add a power supply and possibly having an arduino board mated on top of the circuit board perhaps to bring more of the electronics inside.  I might want to try to get a Digilent board perhaps to try converting to it as a transition between Arduino and PIC32 before I completely switch to a dedicated PIC32.

I’ve also been looking at possibly creating a dedicated PC application to communicate with it directly via USB and over ethernet.  I am toying around with the “QT/QML” language but havent gotten too far with it.  I may just go back to Processing though.

Ordered more stuff – headaches and new replacement stuff

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I had a “Chromalyte” LCD screen that came from EIO.  I needed some sort of cable for another thing going on at home and EIO came up having it in some google search.  It was cheap and the price for a similar cable from darn near anywhere else on the planet was about 5 times higher plus obscene shipping on top of that for something that ultimately ends up in a padded envelope and has $2 of postage on it.  Anyway this LCD was supposed to do 20 characters by 4 lines.  Currently I’ve been using a 20 by 2 lines LCD by Newhaven.  The Newhaven works great.  The Chromalyte?  Not so much.

I googled Chromalyte looking for a data sheet and figuring there may be some info somewhere on the internet about it and maybe using it on an Arduino project or something like that.  I noticed I kept finding pages for EIO.  I looked the product over and kept trying to find some sort of marking on it.  I looked at the data sheet found on EIO and it was pretty basic.

It mentioned using some sort of software available for download from Chromalyte’s website to test it from your Windows PC.  I figured maybe I could try that and tried harder looking for some sort of Chromalyte website.  I threw Incorporated into the search and still kept coming up with EIO.  I really started to wonder at this point and went to Archive.org looking for historical websites that were named Chromalyte.  What I discovered?  EVEN YEARS AGO Chromalyte dot com pointed to EIO’s sales pages.  Today?  It’s current contents?  It’s a GoDaddy “is this your website” listing.  But with the history seeming to always be EIO they don’t even seem to be a real company and are instead just a propped up brand name for EIO.

What made me look into Chromalyte so much that I was having problems with?  Newhaven LCD I can serial.print and serial.write decimal or hex codes to it all day long…. move the cursor around on the screen, clear the screen, put text anywhere etc.  Chromalyte? I print serial to it and nothing happens.  I throw in slash n and r to see if that helps and it doesn’t.  I try sending hex codes for all sorts of thing and nothing.  If I serial.write a clear screen it wipes the screen.  If I serial write movement commands and turn on the cursor I can watch the cursor dance around all over the screen.  I print more serial to it and nothing happens.  I serial.println to it? I get a white box IN FRONT OF the text and the line that I want anywhere I tell it to move the cursor to.

Is there anything about this in the data sheet?  Nope.  Anyone used one on an Arduino?  Not that I can find…. Heck if it wasn’t for EIO listings all over the place I don’t think anything comes back about Chromalyte at all.  I’d have to format some search keywords to force it to drop out EIO responses just to see if I could find anything else because when I searched for that name every entry for pages and pages came back as EIO.

The codes it uses are really bizarre compared to most other LCD brands available.  I think I found someone’s code ONCE that actually used a similar command structure for clearing the screen and moving the cursor but all of the other codes were different.  I’m not a stranger to writing to serial driven LCD as well as using parallel, SPI, and I2C to write to text and graphic LCDs.  This thing is just plain weird.

Sure I could probably email EIO and bitch about it but if this thing is this weird it’s just not worth it to me.  It was cheap enough compared to the hundreds and hundreds of dollars I’ve spent on all the other hardware to build a coffee roaster that it’s but a blip.  I just don’t see myself buying another one, ever.

If anyone out there can send me an Arduino program that DOES indeed work on a Chromalyte labeled as a c420a that simply clears the screen, writes Line 1 to line 1, Line 2 to line 2 and so on I’ll be amazed.  If such a thing does occur I’ll permanently install the screen in a project I’ll be doing later to read a flow meter and open/close a water valve on my reverse osmosis water system so that I can punch up a 1/2/5 gallon fill without needing to watch it.  I’m hoping to have it monitor my total water into the system and the output into a bottle and then monitor TDS sensors to gauge water purity.  Then have it alert me to change the filters and keep track of water input purity throughout the year.

To my girlfriend:  Yes I am too lazy to set a timer to track how long I’ve been adding water to a water bottle.  Instead I will design a circuit, solder up a board, write software for a microcontroller, and then mount the thing in a case so that I don’t have to set a timer so I don’t overflow the water bottle.  I know my limitations.  Building a system to turn the water off by itself is FAR easier for me to do.

So anyway today arrived a Newhaven NHD-0420D3Z-NSW-BBW as well as a pair of PCB solderable DB25 connectors, a bag of 100 B3F-1000 type Omron buttons and a few Maxim MAX31855 thermocouple ADC chips.  I figure I’ll make a board up that does 4 inputs at some point so I got enough to do that plus a couple spares.  I still need the sockets though.  Nobody seems to sell those except for Ryan McLaughlin.  After the MAX31855 that he switched to from the MAX6675 became scarce he shut down his store.  Hopefully he will pop back up sometime soon since his boards were really well made and I think he’d be a great resource for DIY’ers building smoker controllers and coffee roasters and other such things.

Anyway this weekend I will be doing my taxes and then spending the rest of time soldering pins to the Newhaven display and connecting it to the roaster controller.  This past two weeks I converted the entire roaster program over to Arduino 1.0 and updated all of the Libraries that I was using to the latest versions.  I few I had to modify slightly due to them not being 1.0 updated but the majority of them were available on the internet updated already.

The conversion to 1.0 made me make a note of all of the libraries I had used and begin to create a list.  If you look at the menu bar you will see “Resources” up top.  This allows you to pick an Arduino link and then get links that go to sites to download the current libraries if you are looking to build your own project.  I’ll be adding a few more projects and libraries that seem useful to DIY Coffee Roasters (and controllers) over the coming weeks too.

Hey you…Yes you…This is what I’m building…

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I’m focused on building a Roast Controller GUI to automate and track my coffee roaster.  I wanted to document my progress and share as much as possible.  For several months I seemed to spend a LOT of time trying to deal with blog spammers instead.  It’s sort of weird having all these bells and whistles for the blog software.  I’ve got all sorts of filtering tools installed to stop the blog spammers from even SEEING the blog.  Then for the ones that don’t get stopped looking at the blog there’s yet another array of tools to stop known spammers from registering accounts and commenting.  Pretty much on a DAILY BASIS the system automatically kills upwards of over 150 unique IPs trying to spam this thing.  This leaves the rest of you that stop by here and look things over.  I like you guys.  Every so often I get a comment or an email from one or two of you so I at least know some of you come back regularly and a few have even started following on Twitter.  I know some of you are curious what exactly I’m trying to do as my “target” roaster.

If you’ve been around enough to read the older blogs and/or looked in the forum you might have seen some of the parts lists that I’ve purchased on my path to automation.  I’ve mentioned a few tools I’ve used to develop various pieces and I figured I’d show you some of what I’ve been up to… First of all I need to build a “development board” for coffee roasting automation that will be migrated from Arduino to PIC32 eventually.  I’ve had some renderings made of portions of my current “board layout” I’ve been slowly cobbling together.

View showing dual TRIACs and Heat Sink w/ High Voltage Terminal connections.

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Low Voltage pins, position for DB-25 interface to a micro controller wire harness and the control panel socket.

Finally is my favorite piece that I’m eager to get to.  When I can finally get my PIC32 project back up and running I have a GUI mostly built that I need to replace the smaller one with.  I used a tool called VGDD by a guy named Fabio.  His website was found here: http://virtualfab.it/mediawiki/index.php/VGDD:Visual_Graphics_Display_Designer

This product is used to design GUIs for Microchip brand processors.  These include (mostly) the PIC18, PIC24, and PIC32 that can use the Graphics Object Library (GOL).  The Microchip provided tool is pretty much a very crude tool that yields complicated junk that needs a LOT of effort to integrate.  Fabio’s product instead turns the entire process into something pretty simple, allows you to actually write code quicker to control the screen transitions by pressing the buttons and then simulate it (AND send it to other people to review) without ever having to compile it.  It makes the Microchip system quite attractive to create a GUI on.

The great part is with the new GOL 3.0 and some new graphics chips you can create higher resolution GUIs and this development tool doesn’t seem to mind one bit.  One of the screens I built for watching the roast will look like this on the 7″ touch screen.  I cropped a roast curve from one of the logged roasts I made a few weeks ago into the blank space for the graph.  At this time VGDD does not appear to have the chart/graph function included into it.  I’m thinking there’s a way to allocate the space for it in the system but I haven’t really concentrated on it.

Simulated Auto Roasting screen prototype from VGDD.

I figured I needed to clue more of you in as to what was going on and hopefully this helps explain it!

Some of the buttons/controls will change slightly as time goes on but I figured I needed to start allocating space for things as I came up with the ideas and see if it made sense.  As you can see from the date on the GUI mockup there’s been a long time since I started working on that screen.  With the recent Arduino progress I’m feeling like I’ll be getting back to the fancier GUI that will sit on top of the Arduino back end in the coming months.  Eventually I’ll convert some more functions BACK to the PIC32 system since it seems to run faster and can do more of the math faster.  Then I can free the Arduino up to just responding to commands.

Roast controller now at full power.

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So I’ve played around with the PID settings.  I haven’t officially sat down and tried to do a “real” tuning since the processing app I’m using right now lets you play with different numbers and feed it back to the Arduino to tweak it.  As a result I came up with a few numbers that flattened out a lot more than it did previously.

First roast with crudely adjusted PID

Next I will need to take it more seriously I wipe out the configurations, dump some junk beans in, and fire up the roaster and calibrate until I can’t stand it anymore and then roast some coffee again.

In regards to the button controller I have figured out a layout that I will likely use but I’m trying to keep this accurate on the schematic system I’m working with to build a real PCB later.  For whatever reason the part in the system appears to not match every other part I’ve seen out there and what I’m currently working with.  I also need to go back to radioshack and buy a resistor I’m going to need because the big multi-pack I have doesn’t include that one resistor that I need to make the math work.

The last couple roasts with this new controller turned out decent enough.  After 3-4 days rest they had extremely good smells (but tasted only “pretty good”.)  Today’s two tests are MUCH closer to ideal roasting the way they worked out and the smells (and the smoke detector) agreed at the right times.  I’ve got two batches waiting that will get consumed over the next several days and we’ll see how it’s going as they rest.  I’ve got a single serve coffee brewer that’s working out better than some of the other ones so it will take me some time to work through all of the beans.

Ahh the smell of progress… roasting coffee!

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So as I mentioned yesterday I roasted some coffee.  This time (except for manual control of the fan) the roaster did it all by itself.  I had given it a handicap of limiting power to the heater only to 85% of the capacity but it appears to have worked ok.  The Arduino roaster controller worked well enough considering the state it is in.  Power control from the Arduino worked for manual potentiometer signaling the fan speed and a data array of settings for the heat controlled the roast automatically trying to maintain the temperature.

I’m going to increase the power again to 90%.  The room temperature was around 45-50 degrees since I roasted it out in my garage so I think it did pretty well getting to temperature.  I’ve also bumped the fan up slightly to a higher maximum.

I will need to get a button controller going soon so that I can force the system from automatic into manual mode so I can quickly shut down heat if necessary without having the laptop connected while letting the fan continue to run.  I’ve got a CAD type design of a PCB going that has a button controller but I haven’t ACTUALLY prototyped it out on some RadioShack boards.  I do have some etch-able boards here to try a toner transfer to build out some controls.  I still need some carbide drill bits though for drilling the through hole parts and the jumper connectors.  If I had SMD header pins I think I actually have all the parts I’d need to build a 6 or 7 button analog pin matrix.  I may need a couple more resistors though to pull that off.  I’m pretty sure I could get at least 4 buttons though.

The power control system had started to get out of control with the heat sinks so I had to beef it up some.  Before anyone says it I know the large heat sink is on upside down.  I didn’t want to drill the board before I was sure it was going to work so those bottom pins are sticking out the top.  I’ll probably run it like this for a little while until I make a permanent board though.

So for those of you keeping track… I went from this:

First working prototype in Radioshack Project Case

To this:

This is MUCH better for the following reason…heat sinks got out of control and all the wires were getting obnoxious:

Next Steps?

  1. Increase allowed power to heater
  2. Make button control pad.
  3. Tune PID.
  4. Improve CSV log system.
  5. Add automation to the Fan control.  Use mild PID triggered adjustments to the fan.  Coarse heat changes by heater.  Minor heat changes (a few degrees) by Fan.
  6. Add current sensor to judge wattage to the heater.
  7. Get profiles loading from SD memory using button pad to select them.
  8. Begin creating circuit to connect my original PIC32 project to the arduino over serial / rx/tx or other communication method.
  9. Complete 7 inch touch screen (I have a screen designed but it’s not entirely stable yet… the backlight flickers occasionally and the image stutters here and there but it’s there…)  I’ll upload a bitmap from the layout tool soon.
  10. Migrate most functions to PIC32 eventually.
  11. Build a final PCB.
  12. Get a case made for it.
  13. Roast lots of coffee.
  14. Brew it.
  15. Drink it.

That heater (triac) is HOT…

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So today at lunch I threw some beans into the roasting chamber and then ran the roast controller to see what it would do. The wild swings were much flatter today and appeared to get “tighter” on the swings as it went but then a short while later ran out of power again due to my self-imposed limit. I’ve got a joint issue on the potentiometer for one of the soldered on wires possibly losing contact causing the fan to jump around. Finally… the heater TRIAC is pretty hot. It’s not enough to burn you but it’s way hotter than it should be right now.

I’ve got a box with some heat sinks in it that I need to dig out. I picked up a lot of odds and ends the last time I was in Sonoma County, California. There’s a surplus parts company down there that I bought lots of wire, connectors, various sockets, heat shrink etc. One of the items I purchased was a small selection of heat sinks in various sizes and shapes that were compatible with the package of the TRIAC I use to run the heater. The heat sink I have installed now is not meant to be used for anything very hot. It’s great for the fan transformer but for 1000+ watts of heater…. no. I’m not certain I can get it to line up very well without possibly needing to remount the other heat sink and then bend it slightly before installing the larger one. I may need to rebuild the power control board or instead focus on building my custom PCB more quickly.

Update: I’ve procured an IR spot thermometer. It appears that the Triac package is hovering around the upper range of the package. It seems to be JUST enough to keep it from overheating by about 10 degrees after I allowed more power in the software right now. I am about 1/4 inch too tight to make the bigger heat sink fit so I will rebuild the board today to see if I can make it work. The PID is actually showing a faster response to flattening the swing and staying flat faster and longer with the extra power but I still need a small amount more power to be ideal and run a full roast. /Update

In other news I couldn’t stand it any more and ended up pre-ordering the ZPMEspresso.com Nocturn Espresso machine. Over the next couple hours they have it at a $300 price instead of a $350 price it will be later tonight. Eventually it will go up again to the $400 price it will remain at when they start producing them. I’m such a geek that I HAVE TO have an espresso machine that I can reprogram. I’ve done so much with the Arduino on this coffee roaster I just CAN’T not get one now… especially with a discount!

Guaranteed I WILL be hacking this thing once I get it. They’re doing a great thing the way they’re building it but it’s lacking in a few areas that appeal to the REAL geek that wants to hack it. I already know where I’m going to start… muahahahahahahaaaaaa

First test run of the Arduino FreshRoast SR500 Controller

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This afternoon when I was home for lunch I ran the Arduino control touching a light bulb plugged into the heater output.  It tracked the heat pretty closely until it got up around 300 degrees.  It overshot by about 10-20 degrees initially and then once it caught up it was pretty close the rest of the way pulsing the power as necessary.  After it neared 300 degrees it couldn’t keep up and started lagging.  At that point I left the fan running at full speed for the duration of a normal roast.

This evening I went out and plugged in the heater.  The heater is a totally different monster!  It tracks but it OBVIOUSLY needs the PID calibrated until it works better.  At low fan when the heater dies down it has a massive swing in temperature going under and then back over again.  It appears to only do ok at the lower temperatures and then is all over the place at the higher temperatures.  What is noteworthy is that it DOES track the same “slop” drift around the target temperature all the way up.  The drop/gain on the % power is simply too drastic and needs to be adjusted to flatten out more.

For giggles I’m throwing out for view a test graph as it ran (no beans) for a few minutes once with low fan and another with higher fan.  I have the heat maxed at 80% power in the program so that I don’t burn anything up accidentally until I’m sure it can run like it should.

First Arduino Roast Controller test with heater connected

In the lower graph it shows a low fan vs a higher fan setting.  The middle one is a heat amount that actually gets reduced to 80% in the code during testing.  The green in the top graph is the target while the red is the actual temperature reading. Both tests were run with the roasting chamber left empty.  I’ll try adjusting the PID settings a little bit to smooth it out to have smaller sweeps and then start loading some old green coffee in to test it with a “load” and see  how much that stops the swing.

Now that the heat is able to be completely shut off this helps the temperature drop a lot faster.  It’s my guess this would be better for the roaster overall to completely drop the temperature of the coils before turning it off while it cools the beans.  I’ve set the system so that the cooling requires the probe to reach a low temperature before turning off so the coffee beans should be quite cooled before it shuts down by itself.

Nearing a rough prototype roast controller setup

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I haven’t had a lot of time to work on this project lately.  A few weeks ago I had ordered a variety of jumper/header crimp pins, housings, and tools to crimp with.  With those ends I’ve pieced together “arduino compatible” wiring harnesses to go between break out boards, arduino and to the perfboard and other pieces I’ve thrown together.  As a result I feel I am now approaching a rough prototype roast controller.

One of my other purchases was a “Crib for Arduino” to mount some of the pieces inside a box that were not already part of the RadioShack case pictured in my last blog entry.  Most of the crazy wiring on the Arduino photo has been woven together into separate bundles and connected directly to the DB25 connector cable which I’ve also been slowly crimping together.

I would have been testing the fan and heat controls last weekend (and when I had time this week) except that when I finally got it hooked up the fan and heat were no longer “smooth” but instead stuttered all over the place.  It had been quite a while since I had the Arduino side of it hooked up to the mains power so I had to go through and double check all the wiring in the harnesses and DB25 hookups.  Eventually I figured I’m either overloading it with the service schedule on reading sensors and writing to SD, updating the screen and not having time to trigger the mains voltage properly or else the timer wasn’t triggering properly.

Once I had confirmed all the wires were right I looked up the interrupt lines and timer lines in the Arduino website and realized the code probably had the wrong interrupt in there.  Several months ago while trying to clean up some of the code I remember having accidentally typed over the interrupt number in the attachinterrupt line and saved it without realizing it had been modified while updating other code.  Once I returned it back to the proper interrupt for the pin I was using everything worked again.

Tonight I tried running a load of beans through the roaster on fan only.  I believe my adjustments for the fan power are slightly off because the beans begin moving a tiny bit too far into the % potentiometer.  I’ll need to try running beans in an unmodified roaster and pay attention to the level of movement in both roasters based on the position of the knob.  If I had some sort of manometer it would probably help more but I don’t have one.  There are several DIY projects that appear to have built one that I’ve seen months ago that I might end up trying to look up again but I’ll have to see how well it goes without it.

This weekend I’ve got other things going on so it will probably be over the next week and following weekend that I try to calibrate the fan and then the heater.  Once I’ve accomplished both things I’ll begin testing the PID settings to see how well I can control everything to automate the roast

Once the automation appears to be working I do want to add a few additional sensors still.  I then will start working on an Arduino to PIC32 conversion of the controls adding the touch screen and using it to send instructions to the Arduino.  Then slowly migrating more and more sensors and devices back over to PIC32 until eventually I’ve eliminated the Arduino unless it proves helpful to have separate microcontrollers for specific functions.  There will probably be a basic Arduino compatible roast controller in between that will be built onto a PCB that will be professionally produced using one of the quick PCB prototype companies.