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Modifying the machine

A project log for AVR controlled espresso machine

ATmega32 based controller/display for my old espresso machine. It controls brew/steam temperature, pump, grinder etc.

Tobias RathjeTobias Rathje 02/01/2016 at 10:460 Comments

While comtemplating what to do with the machine I stumbled upon this post:

http://coffeegeek.com/forums/espresso/machinemods/522994

It seems like this machine wasn't really optimally designed from the beginning. By adjusting the existing over-pressure valve I managed to get much better results from the machine.

But still those crummy mechanical bimetal thermostats were annoying me, and I needed some automation.

At first I used a couple of cheap industrial timers and a PID controller along with some solid-state relays to control the pump, grinder motor and heater, but they were clumsy and impractical so I decided to modify the machine for an external MCU-based controller.

I kept the solid-state relays, replaced the PID sensor with a LM35T and connected the appropriate wires to a D-Sub 9 connector on the front panel instead of the original switches.

After testing that everything was working using the connector, I was ready to move on to building the controller...

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