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renatoa
03/25/2024 12:38 PM
coffee drink, Ramper?

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03/23/2024 3:02 PM
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Arduino, PID, or ???
CharcoalRoaster
A super newbie question in terms of datalogging and controlling roasts.

What is the difference between an Arduino and PID controller? Are they the same but using an Arduino board requires a build out by the user?
 
Dan
There is quite a bit of overlap since both can control the heat in a roaster including profiling. And, with the proper setup, both can do datalogging. Plus, both can control other aspects of a roast. By the time you buy the extra shields such as the TC4, the cost is about the same. The major difference, to me, is that the Arduino setup can store multiple profiles while PIDs can only save one.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
CharcoalRoaster
In terms of programming, I'm gonna guess that the PID is more intuitive while the Arduino requires a bit of programming knowledge or practice?
 
Dan
To program a PID you follow an onboard menu and select values. While not intuitive, it is straight forward. To program an Arduino you write code and upload it to the unit. If someone gives you the code, then you just have to upload it. That's oversimplification, but that should help you.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
bvwelch
With the Arduino approach, you have a lot of choices, which can be great, but could be a source for confusion for some.

Strickly speaking, most of the work with the TC4 and TC4C has been on manual or semi-automated roasting, although there is at least one PID program available.

Personally, if you are new to roasting, I would not worry so much about PID, but rather choose the TC4C and one of its 'canned' (preprogramed) solutions, which will allow you to monitor, and/or assist you in manually roasting.
 
Dan
In the end, I think you have to weigh the learning curve (steeper for an Arduino) with flexibility and features (better with an Arduino).

When I first mentioned using an Arduino for roaster control I was hoping that this low-cost solution could be developed by our techies using an Arduino without any shields except for perhaps an LCD, but designed so that any DIYer could implement it using easy, step-by-step instructions. So far, that hasn't happened; I hope it does, soon. I would like to make that contribution myself, but just don't have the skill set and time.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
oldgearhead
I think the more important question is 'open-loop' or 'closed-loop' control.
PID,PI, or just 'P' are closed loop control. In other words they try to maintain a constant 'set-point'. The problem with that is a reverse acting PID controller will start turning down the heat too early for coffee roasting needs, unless multiple set-points are used as with a ramp/soak feature.

Rate-of-rise (RoR) control seems to be better suited to coffee roasting. Why, because heat, especially electric heat, needs to constantly advance throughout the entire roast, but it needs to gain more during the 'ramp-to-first-crack' stage, than during 'drying' or 'finish'.

RoR can be implemented in either a 'closed-loop' or 'open-loop' control system.

My fluid-bed roaster has 4 controls:
1) Watts to heater
2) Blower speed
3) Ambient temperature door position
4) Hot-air dump door.

Three of these input controls need to be adjusted during each roast.
I use open-loop manual control while keeping an eye on RoR with a stopwatch and BMT probe.

Yes, I could add a couple of solenoids and automate the thing with a PLC, but the coffee wouldn't be any better.
oldgearhead attached the following image:
dsc_8386_6.jpg

No oil on my beans...
 
bvwelch

Quote

Dan wrote:

In the end, I think you have to weigh the learning curve (steeper for an Arduino) with flexibility and features (better with an Arduino).

When I first mentioned using an Arduino for roaster control I was hoping that this low-cost solution could be developed by our techies using an Arduino without any shields except for perhaps an LCD, but designed so that any DIYer could implement it using easy, step-by-step instructions. So far, that hasn't happened; I hope it does, soon. I would like to make that contribution myself, but just don't have the skill set and time.


It seems like the TC4C comes close to meeting your concept -- it is a single board, pre-programed. LCD is optional, but available. Have you tried one?
 
Dan
I thought the TC4C was a shield for an Arduino, so that makes it two boards, right?
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
greencardigan
No, the TC4 is the Arduino shield.

The TC4C is essentially an Arduino board and TC4 board merged into one.

http://code.googl...c4-shield/
 
bvwelch

Quote

greencardigan wrote:

No, the TC4 is the Arduino shield.

The TC4C is essentially an Arduino board and TC4 board merged into one.

http://code.googl...c4-shield/


Right -- just scroll down the page above to find the single-board TC4C
 
JimG

Quote

bvwelch wrote:
It seems like the TC4C comes close to meeting your concept -- it is a single board, pre-programed. LCD is optional, but available. Have you tried one?


The optional LCD board, including keypad and status LED's, can be piggybacked on the TC4C. Configured this way, the assembly ships out as a single brick that fits inside a 4" x 3" x 2" box.

Prototypes of a couple of acrylic enclosures are in the mail to me as I "speak". Similar in concept to the Raspberry Pi enclosure that Adafruit sells.

If all goes well with the enclosure prototypes, then soon there should be a system available that comes pretty close to plug and play for roast monitor/control.

Jim
 
Dan
That's what I thought. The TC4C IS a custom shield that attaches to a standard Arduino board. Pounder Plus' link states in the title it is a TC4 Shield. I was originally hoping for an Arduino used neat, without any shields other than perhaps an LCD. While I am sure the new board adds value and function, it also means that fewer roasters can implement it. Fewer people have the skills and wherewithal to make a finished roaster. I'm not putting down this turn of events. Taking it a step further is natural, especially for this group. I'm just disappointed that there isn't a simpler, off the shelf controller that a non-techy could use.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
bvwelch
No, the TC4C is a standalone board, which combines all of the circuitry of an Arduino plus all of the TC4 shield circuitry, on a single board.
 
bvwelch
Most folks seem to want to use thermocouples for their coffee roasting. These devices output millivolts, for example, the K type, from room temperature to 500 F, is about 0 to 10 millivolts. Microprocessors, such as picmicros and atmel avr, Arduino, Raspberry Pi, expect and input from 0 to 5 volts, or maybe 0 to 3.3 volts. Thus, some circuitry is required. There are many solutions to this, and most are quite expensive, or hard to calibrate. The chip we chose works well, and costs about $1 USD per channel.
 
Dan
Dang, I was editing my post but when I saved it too much time had lapsed and it didn't show up. Here's what I was wanting to say:

I checked out the link Pounder Plus provided and I see where the confusion is. The TC4 IS a custom shield. It even calls it an Arduino shield.

Now I see there is a non-Arduino controller with thermocouple inputs. I didn't know that was available in that configuration.

Still, my point stands. When I posted about using the inexpensive Arduino four years ago I was originally hoping for an Arduino used neat, without any shields other than perhaps an LCD. While I am sure these new boards add value and function, it also means that fewer home roasters can implement them. They create one more hurdle to jump over. I'm not putting down this turn of events. I know that datalogging is important for some roasters. And taking an idea a step further is natural, especially for this group.

I'm just disappointed that there isn't an easy to upload code for controlling a roast with multiple profiles that a non-techy could use that uses an off-the-shelf Arduino board. Granted the TC4C is sorta off the shelf, but since it is a limited run item I wonder about its sustainability? Will it be around 3 years from now? Five years from now when someone needs a replacement?

Yes, I understand that using thermocouples is a challenge and perhaps using a custom board is the only way to accomplish that task. Nonetheless, I'm intrigued with the TC4C concept from a technical-curiosity standpoint and, time willing, I'd like to see how it works on my sample roaster. Right now it has separate manual and PID control. Might as well add a third one!

How many TC4/TC4C have been shipped to date?
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
bvwelch
Yes Dan, your early suggestion for the Arduino prompted me to switch from using the picmicro to the Arduino -- we can probably find that early discussion thread somewhere. I am glad for your suggestion, and the switch to Arduino,

and especially glad that JimG jumped in and took the project to a whole new and better level ! Thanks to you both! and lots of others are doing great things too!
 
bvwelch
Dan's early thread --
http://forum.home...post_11755

and the resulting brainstorming thread for the TC4:

http://forum.home...ad_id=1774

many many folks here provided tons of good input that shaped the project in many good ways!
 
JimG

Quote

Dan wrote:How many TC4/TC4C have been shipped to date?


Don't have a precise count. Best estimates are around 50 of the TC4C, and maybe as many as 150 TC4 shields? I am basing that on the number of times I have had to order new bare boards from GoldPhoenix.

Just to fill in a bit more background, I had been working independently for more than a year on an analog solution to reading multiple thermocouples. Boards full of op amps, precision resistors, and other distasteful things Shock

Then I came across Bill's thread describing the 4-channel ADC chip and realized immediately I needed to switch my project from analog to digital. The TC4 shield was the first step, with the TC4C ultimately being the solution to both the roasting application and my original project goal (espresso machine control).

So I have a pretty good understanding of the issues involved with reading thermocouples with any sort of accuracy. Trying to use the 5V 10-bit ADC on a "bare" Arduino to read thermocouples would be nearly impossible, unless you only needed to be able to resolve sorta hot vs real hot ;-)

Bare Arduino's can be used successfully with other types of sensors, including RTD's and semi-conductor type sensors. But I think thermocouples are the right choice for roasting, so it leaves us with the need for some kind of supplemental electronics to pair up with an Arduino.

Jim
 
Dan
Thanks, Jim. I knew there were issues with the microvolt sensors and the cold junction needed to use thermocouples. I have more PIDs and TCs at home and at work than I can count. And, I value the ability to control temperatures in 15kW ovens to ?1? that you get with PID algorithms and thermocouples. What this tells me, and I know we've taken us a little off topic, is that its starting to sound to me that the issues and constraints have taken you guys to the only(?) possible solution that's inexpensive enough to be useful. The reason I asked for the number of units shipped was to judge how popular your approach is. 200 units for a group of 2400 members in HRO is a VERY good ratio. So, I'm changing my mind. I no longer think an Arduino-neat solution is viable. Now, on to my other concern.

So, if the TC4C is the optimal solution, how to insure that it is sustainable? What if you guys aren't around to make/stuff/solder these boards? How to make sure this is indeed an open-source project? Do you have plans in place or some ideas about that?
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
JimG

Quote

Dan wrote:
So, if the TC4C is the optimal solution, how to insure that it is sustainable? What if you guys aren't around to make/stuff/solder these boards? How to make sure this is indeed an open-source project? Do you have plans in place or some ideas about that?

All of the source for all of the applications is on the project googlecode site. So are the hardware schematics and board layouts.
http://code.googl...c4-shield/

The code is all released under BSD license. The hardware is CC-BY-SA. There is enough information out there for anyone who wishes to spin their own to do so, and the licensing is intentionally less burdensome than the LGPL under which the Arduino libraries are released.

Whether or not someone else would be foolish enough to solder these things up and ship them all over creation is another question altogether Roflmao

Jim
 
Dan
LOL! Thanks for the info, that's good to know. Being a manufacturer, I know exactly what you mean! And no, I don't want to make them. I have one business to run already. :)
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
JimG
I have tried to discourage orders for the fully built shield by effectively charging $25 for soldering the through-hole components. As a result, nearly all of the orders for the shield are for the kit (consisting of the board pre-populated with SMD components, plus a bag of loose through-hole parts). Building the shields goes fairly quickly since I can make 7 per batch in my Walmart reflow oven, so I can keep them priced pretty low.

Even though the TC4C's are priced a little higher, building them is very time-consuming and not at all financially attractive in small volumes.

But I think it is the key to wider use of the TC4 system. The TC4C eliminates the need for using the Arduino IDE for those who want to just plug it in and go, but remains fully compatible with the Arduino system for those who want to try their hand at custom programming.

Jim
 
greencardigan

Quote

Dan wrote:
I'm just disappointed that there isn't an easy to upload code for controlling a roast with multiple profiles that a non-techy could use that uses an off-the-shelf Arduino board.

So you want a system that automates the heater control to follow a selected profile? I had assumed, based on other HRO posts, that most people still prefer manual control.

To date I believe it's only my code (aArtisanQ_PID) and maybe Randy's (aKona) that allows both manual AND/OR automated PID control with selectable roast profiles WITHOUT a computer connection.


Quote

Dan wrote:
Granted the TC4C is sorta off the shelf, but since it is a limited run item I wonder about its sustainability? Will it be around 3 years from now? Five years from now when someone needs a replacement?

We (the TC4 system) seem to have good support from the developers of the RoastLogger and Artisan roasting software packages. I think strengthening those links will help boost the number of users and help it to survive.

I'm sure there are lots of other potential users too beyond coffee roasting. Smokers, brewers, aquariums... etc.
 
Dan

Quote

greencardigan wrote:
So you want a system that automates the heater control to follow a selected profile? I had assumed, based on other HRO posts, that most people still prefer manual control.


I don't know the ratio, but I do know that the Fuji PID is popular with HRO folks because of the profile feature. If I want to manually control my sample roaster I just use much cheaper and simpler percentage timer. I don't know about others, but I don't need to spend more money, more time, and walk on glass debugging an automated device just to end up bypassing its automation.

Quote

greencardigan wrote:
To date I believe it's only my code (aArtisanQ_PID) and maybe Randy's (aKona) that allows both manual AND/OR automated PID control with selectable roast profiles WITHOUT a computer connection.


I'm glad you brought this up. It's a question that I couldn't find the answer to on the project page. None of the descriptions mention the ability to program a profile or how many can be stored. From what you've said, both the aArtisan and aKona can profile. How many profiles can they store? Where can I find more information about these two programs?
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
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