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[Project] New firmware for coffee machine


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Just thought I posted my long-time pending project - a replacement chip solution for the Senseo coffee pad machine. It's not 'in production' yet, will do so in the following days, just a bit nervous about playing with line voltages. The machine uses/used a capacitive divider instead of a small transformer, which means that most of the stuff is at line potential with reference to earth. Original voltage regulation is done by clamping 220V through a 5V zener.

It has been thoroughly tested on the breadboard so it should work once installed.

 

Hardware - mostly stock, I'm just putting in the MSP430 chip and a regulator. I kept the original board and removed the uC and EEPROM chips.

- three buttons: power, 1 coffee, 2 coffees

- the power button has a small red LED circle around it

- heater controlled via an SCR

- NTC thermistor inside the heater is sampled through a voltage divider.

- water sensor is a hall type sensor that detects the floater position inside the water tank

- water pump is controlled via a small transistor

 

Operation:

- while line voltage is on but the machine is powered off the user can enter service modes via button combinations

- upon powering on the machine starts heating the water, displaying on the LED how hot the water is (PWM)

- if the user requests a coffee, the machine changes is blinking pattern and starts making a coffee once the water is heated

- if there is no water in the tank there is a faster blinking pattern

- if no user input is detected for 30 minutes the machine goes to power off state

- a lot of other safety stuff and under the hood stuff that you kind of expect to work

 

Why?

The original machine annoyed me (and my work mates) for various reasons:

- once plugged in, it stayed off, so if you used a remote outlet you have to physically move yourself to power on the machine, making the remote outlet kind of useless

- heating the water takes quite a lot of time (90s) and you cannot request a coffee in advance

- that 90s seems like forever because you have no indication how far you are from the target temperature; the led just blinks and then settles to an ON state

- if left unused for a while, the boiler temperature goes down quite a lot; this makes the next coffee colder than normal

 

Things to do after real-world testing is complete:

- the 2 coffee button is not implemented yet, not sure it is needed. Two presses of the other button achieve exactly the same thing and the water does not cool so much

- LPM3/4. Probably not needed, but I will test initially with a separate battery supply.

- water quantity calibration via a service mode. You should be able to increase/decrease the pump duration in 1 second increments via a service mode and the value saved in flash. The original chip did this

- add a jumper or some kind of configuration mode where you can have the machine prepare a coffee once it's powered on, for remote controlled outlet usage

 

If anyone needs more details I can provide them here; I will eventual make a dedicated blog post with tons of pictures and graphs about this.

Strangely enough I cannot attach .ino files and the code tag seems broken.

senseopad.ino.txt

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Fantastic work!  Also you used Energia, neat and practical use of the platform.  That's a little scary they use a 5V zener to supply the MCU... I guess it works but wow!  Probably a lot more common than I think.

 

IMO, with that setup, don't bother with LPM3/LPM4.  The MSP430 sips rather little power (few mA's) even in fully active mode.

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Awesome project and great writeup. Thanks for sharing. Do you plan to post this project somewhere? If you do, then I would love to put a link to it on the Energia website under projects.

 

I love that it uses a capacitive power supply. I have reading up on this this for some projects that I am working on and if you know what you are doing then these little circuits can be an awesome solution for a space constrained mains powered circuit.

 

Here's a great writeup by jeelabs that explains how these little circuits work: http://jeelabs.org/2012/01/29/capacitive-power-supply/

 

But if you are Apple then of course you figure out how to cram a real power supply into a small package: http://www.righto.com/2012/05/apple-iphone-charger-teardown-quality.html

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Awesome project and great writeup. Thanks for sharing. Do you plan to post this project somewhere? If you do, then I would love to put a link to it on the Energia website under projects.

 

I love that it uses a capacitive power supply. I have reading up on this this for some projects that I am working on and if you know what you are doing then these little circuits can be an awesome solution for a space constrained mains powered circuit.

 

Here's a great writeup by jeelabs that explains how these little circuits work: http://jeelabs.org/2012/01/29/capacitive-power-supply/

 

But if you are Apple then of course you figure out how to cram a real power supply into a small package: http://www.righto.com/2012/05/apple-iphone-charger-teardown-quality.html

Thanks for that link, gotta keep this in mind (e.g. for remote control triac power strip projects or whatnot...)

 

Sent from my Galaxy Note II with Tapatalk

 

 

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I'd suggest using LPM4 to use the shutdown/standby mode of the Senseo. You should aim for the machine to use as little power as possible when plugged in a live socket.

 

You could use a RF chip with this design to remotely energize the coffee machine (brew me one while I pull myself from the bed in the morning)

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