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Silvia PID build


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Hi,

I'm also doing a DYI PID on ESP32. Coding in MicroPython. 

Wondering why you are not using PID under 85C? The proportional will just give 100% power when the boiler is cold. 

May eventually post on GitHub, but have so far posted some PID code on the MicroPython forum, with anti integrator windup.

 

First step was to just get temperature control. Steam switch as digital in to change target temp. A bit crude:

 

1506540451_IMG_0667(1).png.f5989e6e643dddc3ac024ba2de904c76.png

 

The next step will be a bit more ambitious. Some more components

 

1142916931_IMG_0668(1).png.3f47be7835379cfa438fccbadc98bc35.png

 

PSU, 2 SSR and a pressure sensor. The pressure gauge attached to the original portafilter holder will only be used to calibrate the sensor. Plan to remove the OPV.

Plan to completely re-wire the machine, fit all components inside and connect the switches as digital ins. A pretty major job, that will take some time to reverse. So, a bit hesitant.

Final step could be to integrate a weight sensor under the drip tray or a BLE scale. The Acaia Lunar has documented API, but costs more than what I payed for my Silvia.

 

Daniel

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4 hours ago, Daniel R said:

Plan to completely re-wire the machine, fit all components inside and connect the switches as digital ins. A pretty major job, that will take some time to reverse. So, a bit hesitant.

Hi Daniel, 

Looks good! You’re braver than me going for a full re-wire. Have to admit I fancied doing it, but I just couldn’t bring myself to completely strip down a brand new machine. If I ever do it though, that stupid power saving module is going in the bin immediately! 
 

Are you going to control the pressure or is the sensor just for monitoring? After a water level sensor that would be my next upgrade.

 

As for my PID settings, basically I originally wrote the code for beer brewing in a 50L boiler and couldn’t be bothered to spend too long tuning for the new setup. The performance seemed ok with a bit of playing around, although the settings are way too conservative hence the fudge below 85C.

 

cheers

Jim

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Yep, will try to implement pressure profiling. 

Vibratory pumps seems a bit tricky to control. It has a diode, so that every half cycle is a stroke. I read that having a 250k resistor across the SSR is required for it detect the zero crossing (and work correctly).

Will make sure that I can control pump power before installing the pressure sensor and removing the OPV.

Not sure when I will continue this project. Will probably wait until my wife and kids are traveling, so that I have more time available. Would hate to be without good espresso for longer than necessary.

Also, I have not properly tuned the PID. Just using the proportional for now. Oscillates a bit, but within 1C.

Daniel

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