DIY PID - Koffie Project - Page 2

Need help with equipment usage or want to share your latest discovery?
randytsuch

#11: Post by randytsuch »

Something to consider, if you migrate to an ESP32, they can act as a webserver. So you could use the ESP32 to make a simple webpage for your "display". Then you don't need an app. Any device that has a browser can display the webpage.

I had planned to put a larger display on the side of my machine, but the display was backordered to I had to find an alternate plan. I prefer this anyway, use an old ipad for the browser.

My machine does have a small 2x20 LCD for important parameters, and then I have a webpage to display more parameters, and to input data.

Another neat trick you can do with the ESP32 is Over The Air programming. So you just need power, no USB cables after the initial programming. You don't need to drag a laptop to your machine to update the program.

mwood77 (original poster)

#12: Post by mwood77 (original poster) »

nisb wrote:Fun project!

I'd consider
  • Using something like Blynk instead of a display/rotary encoder. It's much easier/faster to code and with higher usability afforded by the bigger screen of your phone. You can couple it with a small display if there are things you'd like to check frequently without pulling out your phone. You would need WiFi or Bluetooth - maybe using an ESP32 instead of the Nano
  • If adding temp sensors, use thermistors instead of thermocouples. They only require a resistor and a filtering cap, unlike thermocouples which require a special differential OpAmp. Alternatives would be ICs like the DS18B20 or the tmp36
Thanks!
- Blynk is an interesting option I hadn't come across, definitely something to consider/investigate when I migrate it to an ESP32. Right now the encoder is handled natively (position comparison). It's accurate, but it could be a touch smoother, if I'm honest.
- Project currently uses a TMP36. Like you said, much less overhead, and very easy to code in!
ira wrote:Bumps the cost up a bit, but these are Arduino compatible and will not have memory issues, either RAM or EPROM.

https://www.pjrc.com/teensy

1/2 or 2/3 of the way down the page you can see a teensy mounted on a board which would probably work for your needs:

http://roasterthing.com/FrankenBehmor

That's an earlier version, the current version has 3 thermocouples, 5 SSD outputs and 2 mechanical relays. All that's optional, you only need to install the parts you need.

Ira
I looked at Teensys too, but man, $20 for a (very fast) micro controller is pretty hard to swallow when the total project cost is $50-ish. I've ordered some ESP32s and have a handful of Picos around, which is where I'll start. I'm especially excited for the ESP32s to arrive.

Ah, right - you're talking about having a custom PCB with a socket for the microcontroller. Nice idea! I'll explore this once I change architecture, as it would also be dependant on future-proofing the rest of the design.
ira wrote:And I left out Bluetooth if you want to connect it to an App or Computer.

Ira
This was also a consideration, but I chose not to go down this route. Simply because it's additional soldering for the Nano. Luckily the ESP32 can handle this on-board. I'd prefer to stay away from making a dedicated app for your phone/computer for reasons I'll get into a little further down.
randytsuch wrote:Something to consider, if you migrate to an ESP32, they can act as a webserver. So you could use the ESP32 to make a simple webpage for your "display". Then you don't need an app. Any device that has a browser can display the webpage.

I had planned to put a larger display on the side of my machine, but the display was backordered to I had to find an alternate plan. I prefer this anyway, use an old ipad for the browser.

My machine does have a small 2x20 LCD for important parameters, and then I have a webpage to display more parameters, and to input data.

Another neat trick you can do with the ESP32 is Over The Air programming. So you just need power, no USB cables after the initial programming. You don't need to drag a laptop to your machine to update the program.
Exactly!

The ESP32 offers much more than just raw power and memory, which is why I'm leaning in that direction for the next iteration. I want to stay away from creating a dedicated mobile app as that adds a lot of overhead - I don't want to manage separate store listings, compatibility issues, store compliance, dev account costs, etc.

Right now there are a total of 6 wires shared between the PID controller and espresso machine (2x power cords, pressure sensor wire, temp sensor wire, 2x interconnects for the SSR); 4 of these are PID specific. Somebody asked if I could reduce this, which I think is a viable option if I were to consider a master/slave device approach for smaller devices (like the Europiccola). Basically it would have a small sensor box (or hidden inside the base/machine) which would transmit all of the parameters to a dedicated control device - whether this be a tablet/phone/computer or another ESP32.

_Ryan_

#13: Post by _Ryan_ »

ira wrote:Bumps the cost up a bit, but these are Arduino compatible and will not have memory issues, either RAM or EPROM.

https://www.pjrc.com/teensy

Ira
Similar to the Adafruit ItsyBitsy pattern.

_Ryan_

#14: Post by _Ryan_ »

Pflunz wrote:Hi, what is the advantage of your controller compared to other free solutions (like http://projectcaffe.bplaced.net/downloads.html or
That first one you linked isn't open source nor is it really designed to be installed on anything other than the packaged kits they sell.

This is another project of interest: https://github.com/Zer0-bit/gaggiuino