Smart - Coffee: Programmable Espresso Machine Controller
Purchase a kit from the Schematix Store: Click here
Index:
Smart Coffee Software Features
Specifications of the Smart Coffee board:
Power in: 100~240VAC
On board DC power supply: 5VDC, 2A
On board 3.3V power supply: 1A
On board, Solid-Sate relays 100~240VAC live outputs:
2x Boiler element (10A)
1x Pump (10A)
2x Programmable relays (usually connected to solenoid valves) (1A)
Total combined output current limit from relays: 20A
Element 1, and Pump combined max current: 10A
Element 2, RLY1, and RL2 combined max current: 10A
7x 5VDC relay control outputs: (used to control external relays for high current loads)
2x Boiler element
1x Pump
4x Programable relays
Fuse:
2x 5x20mm, 10A
ESP32:
Model: 30pin Development Board
Quantity required: 2
Purchasing link: https://s.click.aliexpress.com/e/_DFc08KN
Inputs/Outputs:
4/6 wire Load Cell Input
I2C display screen interface
2x Pressure transducer inputs
2x Boiler water level detection probes
Brew Switch input
Espresso mode selection input
Reservoir water level detection options:
Reservoir touch-sensitive probe (for detecting water)
Reservoir float switch (compatible with NO and NC switches)
Ultrasonic water level detection
Ultrasonic distance sensor (for measuring water level inside a reservoir tank)
2x MAX31865 temperature sensors (compatible with 2, 3, and 4 wire probes. PT100 and PT1000 series compatible)
6x User programable GPIO pins (M1, M2, S1, S2, S3, and PT3) write your own code to make use of these pins to really customize your coffee experience
7x 5VDC relay control outputs: (used to control external relays for high current loads)
2x Boiler element
1x Pump
4x Programable relays
Smart Coffee Software Features:
Single and Dual boiler compatible with a single group head
PID and PWM logic boiler control
Boiler target can be programmed as Temperature or Pressure
Boiler water level probes (used to trigger a refill when required)
Display metric units (kPa, Celsius, grams, mls) or imperial units (PSI, Fahrenheit, Ounces, fluid ounces)
Pre-Infusion cycle for every coffee extraction (3 stages consisting of: Prime the system > Cycle pump on/off > Extract coffee until the programmed amount has been dispensed)
Momentary or latching switch compatible for Brew and Espresso mode switches
Pressure transducer inputs to control/monitor pressure
Programmable pressure safety limits (machines shuts down when safety limits are exceeded)
Thermocouple temperature sensors to monitor any temperature on the machine
Programmable pressure safety limits (machines shuts down when safety limits are exceeded)
Espresso shot output (when espresso mode is activated by the user)
Espresso shot timer
Espresso shot by weight target (requires loadcell)
Espresso shot by volume target (requires flow meter)
Pause boiler refill (pauses a boiler refill if an espresso extraction is currently taking place)
Ultrasonic distance sensor (used for machines with a reservoir tank to measure the water level)
Reservoir empty standby mode (prevents the machine from operating until the reservoir is refilled)
Programming and wiring guides:
Download the programming guide: click here
Download the wiring guide: click here
Purchase Sensors and Hardware:
ESP32:
Model: 30pin Development Board
Quantity required: 2
Purchasing link: https://s.click.aliexpress.com/e/_DFc08KN
Pressure transducer:
Max voltage input from pressure transducer: 5V
Recommended signal range: 0.5 to 4.5V
Recommended pressure rating: 200 kPa (0.2mPa)
(pressure rating should be at minimum 20% higher than your running pressure)
Purchasing link: https://s.click.aliexpress.com/e/_DkQsvxd
Optional G1/4 to 1/4BSP thread adapter (select type 2): https://s.click.aliexpress.com/e/_DdueKDl
Right angle adapter: https://s.click.aliexpress.com/e/_DE8J34X
Display screen:
Model: OLED SH1107
Interface: I2C
Pixels: 128x128
Input power: 5V
Purchasing link: https://s.click.aliexpress.com/e/_DlH1C43
Load cell:
Weight rating: 1kg
Wiring: 4wire
Purchasing link: https://s.click.aliexpress.com/e/_DdDwihl
4 Pin pogo connector:
Purchasing link: https://s.click.aliexpress.com/e/_DB2fN7N
Small size flow meter:
Model: USN-HS06P
Voltage: 5V
Barb Size: 5mm OD
Flow range: 30 ~ 150ml/min
Purchasing link: https://s.click.aliexpress.com/e/_DCCjQh5
Medium-size flow meter:
Model: USN-HS06PS
Voltage: 5V
Barb size: 7mm OD
Flow range: 0.1 ~ 1.5L/min
Purchasing link: https://s.click.aliexpress.com/e/_DFVTRbV
High-pressure Gicar flow meter:
Purchasing link: https://s.click.aliexpress.com/e/_Dlr1vgB
Thermocouple:
Compatible wiring: 2/3/4 wire
Type: PT100 and PT1000 compatible
Purchasing link for screw mount type: https://s.click.aliexpress.com/e/_DkV2nuB
Purchasing link for threaded mount type: https://s.click.aliexpress.com/e/_DD0nYYx
Ultrasonic Distance Sensor:
Model: A02YY
Output signal: PWM
Input: 5V
Purchasing link: https://s.click.aliexpress.com/e/_DFYOL3z
Switches:
Chrome LED lit momentary switch: https://s.click.aliexpress.com/e/_Dd0BleB
(can be used for the brew and espresso mode switches)
USB panel mount connector:
Purchasing link: https://s.click.aliexpress.com/e/_DksmHhh
Shielded multi-core cable:
28AWG, 2meter
Purchasing link: https://s.click.aliexpress.com/e/_DkdDW87
M3 Brass standoff:
These are handy for mounting the PCB
Purchasing link: https://s.click.aliexpress.com/e/_Dn3mUKB
Bug reporting and suggestions:
If you happen to find a bug in the software. Please send an email describing your software configuration, the sensors you are using, and the bug you have encountered to mail@schematix.co.nz
Updates for Smart Coffee:
Change log and updates:
V1.0 Base version published
PCB Dimensions:
Width: 101mm (3.97")
Length: 153mm (6.02")
Mounting hole spacing: 145mm (5.7") x 93mm (3.66")
Mounting hole size: 3.7mm
I made a prototyping box, just to mount it in while I was wiring everything up. It helped protect it from possible shorts. I would be happy to share that, but it would be much better to wait until I have the final design ready (if you don't mind waiting a few weeks).