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Homeroasters.org » ALL ABOUT ROASTERS » Popcorn Popper roasting
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Poppery 2 and Artisan
swanston
Hi all,
I'm new here so forgive me if this is a FAQ question. I hunted but could not find anything.

I just laid hands on a Poppery 2 and would like to mod it to run with Raspberry Pi or Arduino control (or something). I've roasted manually for years until my last popper died. I'd like to improve my setup and make my roasts more consistent and repeatable.

In searching around I stumbled across Aritsan - wow that looks amazing. I'd like to be able to mod the Poppery to integrate with it. I really assumed there'd be a standard page documenting it but can't find it. Is there such a page, link, forum post? There must be. :-)

Or maybe it is a dumb question and someone can explain why. I'm open to ideas.

Thanks in advance,
D
 
btreichel
either a tc4, which seem unavailable, or look here.

https://nselabs.w...-controls/
 
chaff
Hi !

I have a (Sweet Maria) Nostalgia popper setup with Arduino. If your popper is similar there are two heating coils in the unit: one low power, high resistance coil is in series with the fan motor and serves to limit the curent to the fan. The main heater coil is of lower resistance and is the primary heat source. This coil has a thermal switch in series which cuts in and out at high temperature to limit the highest attained temperature. The switch is mounted on the side of the metal popping chamber; there's another thermal fuse near the heating coil which is a safety cutout, it doesn't reset.

My modification is to take the connections off the side-mounted thermal switch and connect them to the line side of a solid state relay, a 'zero crossing' relay. This connection is line voltage and proper saftey precautions are necessary. The low voltage drive from the SSR is connected to an Arduino output pin with the Arduino supplied at 5v. I have a bare thermocouple clipped to the top of the popper, dipping into the beans. My thermocouple is attached to a breakout board connected via SPI to the Arduino.

Had I known about the TC4 and its software when I put this together I would definitely have gone that route. As it is I rolled my own hardware and software, particularly the hardware is a lot simpler than the TC4 and more amenable to the 'jumper and header pins' approach. If the TC4 becomes available again then it's the way to go. To my mind the Pi is a little too OS/Python heavy for this sort of task.

I've found that, in practice, driving the SSR from an Arduino PWM output pin at just over 30Hz works fine, any beating is smoothed by the thermal inertia in the system. Using breakout boards, say from Lady Ada, means you don't have to bother with SMD soldering so it's possible to put together a simple controller with an Arduino, a thermocouple breakout board and a solid state relay.

Both the software and hardware for TC4 are well supported and have a lot more function. In view of the difficulties in getting hold of TC4 boards, I can offer a software sketch that supports both Arduino and ESP8266 with LCD, Thermocouple, SSR and selector switch, interfacing either to Artisan or logging to Artisan csv format as well as interfacing via ESP8266 web interfaces. I've also done a MAX31855 port to TC4 software which builds OK but which isn't tested. Links to my code were posted on another mailing list some time ago, if there's interest and if is isn't against the spirit of this ML I'm happy to share either work with links here.

Best.
 
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renatoa
The popper models I know available here in EU have a different motor connection, there is no high resistance coil, but a tap at about 1/10 of the main heater coil, that provide about 19V for the motor.
This connection don't allow switching the heater to modulate the power, because the fan will be also affected, resulting in airflow variations.

Back to OP question, you have here another implementation of this concept, Roastuino:
http://www.cybere...org/?p=574
 
swanston
It is too bad about TC4 availability at the moment. No news on that front I assume.

@btreichel - thanks, will investigate.

@chaff - thanks for the great info. Would be much appreciated if you could post your links (not sure on the terms on thie forums though)? Would be interested to peruse before making a final decision.

@renatoa - thanks for the link there too, that's one I hadn't stumbled across. Will look into it as well in more detail. Many thanks!

Much appreciated everyone.
 
chaff
I checked with a couple of people, thank you both for replying; here's my github site:
https://github.co...etech/popc

I just finished checking that the sketch, loaded onto a bare bones Arduino UNO connects to Artisan and runs its 'virtual thermocouple', attached is a screencap following a Ramp / Soak . 'ET' on the graph is 'Expected Temperature' ( there's little point in Environment Temp on my popper ) which is useful for judging PID performance. I built in some delay to the virtual thermocouple, the PID values work a little better with my actual hardware.
I hope it's useful, I'm going to look at adding more thermocouples and also porting MAX31855 support into the real TC-4 software.

www.bitwisetech.com/acap-popcArti.png
 
btreichel
Interesting, I was thinking a R Pi for a dedicated controls display running artisan. Just the std serial (aka serial monitor in the IDE)? Done the MQTT, and the esp8266? With the UNO. What are you using for a broker? BTW, done the 31855, now prefer the one wire 31850. Doesn't suck up analog channels, and gives nice stable readings without having to do any post processing.
 
chaff
The serial interface runs a command set that does the normal things: setpoint, ROR, PID adjustments etc or the interface can be switched to either Artisan Interface or Artisan csv output (for file capture). Switching between modes is by serial command or the sketch can be compiled to start in 'Artisan' mode, when the Arduino presents as a TC-4 .

If the sketch is compiled for ESP8266 then libraries for MQTT, the publish/subscribe messaging protocol, or Websockets may be selected. For MQTT, on my PC, I load mosquitto to act as the messaging broker and paho to display the topic traffic from the PC side. One of the messaging topics is "popc/userCmdl" so publishing a string to that topic causes the Arduino sketch to treat the message string as a command entered over serial. I use Artisan's ability to call external programs for input/output to run simple python.mqtt scripts. I've not accomplished much with websockets yet, except maybe bring my home network down, my bad.

It's a single sketch with compile time switches for UNO or ESP8266; for any of MQTT, Websockets or Wifi Manager you must have ESP8266, there's no wifi support when UNO is the target. You can probably gather I put together a UNO popper controller and then discovered ESP8266, added support to learn about its capabilities. It has few general purpose pins and poor drive capabilities so it's not as 'able' as a UNO in those respects.

The MAX31855 doesn't need analogue channels or post processing, it looks to me the same as the MAX31850 up to the processor interface where One-Wire has the advantage of fewer pins and individual device addressing burned onto the chip. Thanks for the tip. Adafruit offers breakout boards and there's library support so it looks like the way to go for multiple thermocouples.

https://cdn-learn...31850k.pdf
https://github.co...50_OneWire

The RPi certainly offers a lot of function. I haven't looked at the extent of library support for running I2C, SPI, OW etc and I wonder if having Linux and python on top of all that makes for an over-complicated setup. I've done both embedded Linux systems and also bare microprocessors, Ive been very pleased with Arduino's learning curve and the amount of support out there. Chaqu'un !
Thanks very much for the interest, I appreciate it .
 
btreichel
You're right, i was using an 8495, and yep get a lot from adafruit. I like their i2c lcd backpack. Adds 4 pushbuttons, and reduces wire count;again. Btw rpi will run misquito, however, I have an old win7 machine that looks alot like a file server. My esp 8266, just handles the wifi, the UNO does a lot of other stuff. One verision is ssr, another is, ac phase, and one, will be controling a gas valve. I also have a stepper version, and a bldc motor.
 
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