Getting the right coffee dose off of your grinder can be a tedious task - this Arduino sketch will let you chose from 2 - 5 different pre-set doses by the weight [g]
The project was first mentioned @ www.espressobar.dk in this thread: http://www.espressobar.dk/forums/showthread.php?9580-Mazzer-Major-DR-gt-Arduino-timer-gt-Doserless-gt-Polering&p=101197#post101197
Code is basically a danish translation and "adaptation" of the original code found here: https://www.wuala.com/Cosmicos/SoftFidelity/M%C3%BChlentimer/OledTimerWizard/?key=bh3lscgclbc5
Important: 1) All .ino files must reside (and stay) in a folder named "OLEDTimerWizard" like in this repository AND 2) You will need to add 3 additional libraries to your standard library folder (probably C:\Program Files (x86)\Arduino\libraries) - you get them from here: https://www.dropbox.com/sh/7uxorxk525zrtxk/AACaTxeZjhuq60BrImUm0_Lra?dl=0
Documentation (HW and Menu flow diagram) can be found under "Documentation"
The HW shopping list - approx $20 total :)
Double Opto-coupler Relay (switching both N+L), if you like to only switch the Line then you can do with a single: http://www.ebay.com/itm/Two-2-Channel-Relay-Module-With-Optocoupler-For-PIC-AVR-DSP-ARM-Arduino-5V-New-/181752994310?hash=item2a51529a06
Arduino Nano ATmega328 – CH340G: http://www.ebay.com/itm/USB-Nano-V3-0-ATmega328-16M-5V-Micro-controller-CH340G-board-For-Arduino-/311064700128?hash=item486ce6a4e0
Rotary Encoder w. Momentary Push: http://www.ebay.com/itm/12mm-Rotary-Encoder-Push-Button-Switch-Keyswitch-Electronic-Components-Stable-/181601752480?hash=item2a484ed5a0
Encoder Knob, Black Alu: http://www.ebay.com/itm/361333592515?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Momentary push for dose pre-sellect, Black Alu flush: http://www.ebay.com/itm/181585627102?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Note: By "adaptation" I mean changes to my liking(!) Also, to get the smalest possible dosing variation you should maintain a constant preasure on top of your beans in the hopper. Prefarably you should replace the standard hopper with a glass or plastic tube in wich you place a metal load on top of the beans...