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Raspberry Pi Zero Espresso timer

Hi all,

I have a project I could do with some help on. I want to create a timer that triggers when a button is pushed and held. For the duration of time the button is held for, a timer should count up from zero in seconds until the button is released. This timer would be shown on a display attached to the Pi.

For those who are wierd coffee people like me, I have an ECM Mechanika slim. This comes with a semi-manually actuated grouphead (E61), When the leaver is lifted, it pushes on a switch which then powers the pump. 

My thoughts are that a Pi Zero would be great for this due to its size and availability of screens for it, but something I noticed is that most screens will take up all the GPIO pins on the board. I've never gone into this kind of thing with much depth so I don't know how I'd send the switch signal into the Pi while also running the screen at the same time? 

I appreciate this is probably super basic, but the internet is a damn rabbit hole and I just want to know from some experienced people if I'm starting out on a rediculous task or not?

Cheers!

 

Note:

I've not managed to measure the volatage accross the switch while it is activated, I know that while open, it's zero volts accross it. I did read somewhere that it may well be 120v across the switch while activated but i need to check with my machine to double check.

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15 hours ago, A_Rich said:

My thoughts are that a Pi Zero would be great for this due to its size and availability of screens for it, but something I noticed is that most screens will take up all the GPIO pins on the board. I've never gone into this kind of thing with much depth so I don't know how I'd send the switch signal into the Pi while also running the screen at the same time? 

How many pins it will take up is determined by the interface the screen uses / supports. Typically you will see SPI or I2C for RPi screens.
Without getting too technical about it, SPI uses more pins, it is full duplex and supports higher data rates, while I2C is half duplex and has lower data rate.
For your use-case I see no reason to use SPI... I2C will be enough and it uses just 4 pins (data, clock, vcc, gnd).
So look for I2C screens instead.
Like this:

image.thumb.png.269e85ca7a7d6ce9e9bf8b9cc20dc628.png

https://www.amazon.com/HiLetgo-HD44780-I2C1602-Interface-Backlight/dp/B07W5KC65S/r

Or this:
image.thumb.png.e95024f0cc8f1595d230c6c227a50025.png

https://www.amazon.com/Display-SSD1306-3-3V-5V-Raspberry-Nano(White/dp/B09412FX88/r

You get the idea 🙂.

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