Fermento

An open-source incubator for fun and profit. For more information about the project, see biodesign.cc.

Board

• Fab contains the PCB version to send to a professional PCB fabrication house. It has a nice silkscreen and slightly better component layout.
• Homebrew contains the version for homebrew PCB printing. The layout is one-sided for easier manufacturing. Drill plan and assembly instruction sheet included. To accomodate a single sided board, the wiring of the component to the microcontroller had to be changed. The correct pin mapping can be changed by a single line in the firmware.

Bill Of Material

• 1x ATmega328p
• 1x DIP28 socket
• 2x Tactile switch (through hole) (BUTTON1, BUTTON2) (C&K PTS645SM95-2 LFS)
• 2x Resistor 10K (R1, R3)
• 1x Resistor 1K (R2)
• 4x Capacitor 0.1uF, 2.5 mm pin spacing (C1, C2, C3, C5)
• 1x Electrolytic capacitor 47uF, radial, 2.5 mm pin spacing (C4)
• 1x 6-pin 90-degrees header (SERIAL)
• 1x 3x2-pin straight header (ISP)
• 1x 6-terminal screw block (Altech MBE-156)
• 1x Relay, 3VDC switching (Omron G6RL-1A-DC3)
• 1x 13mm buzzer (BUZZ1) (Murata, PKM13EPYH4000-A0)
• 1x DC jack 2.1mm (Kobiconn 163-179PH-EX)
• 1x 32.768kHz crystal (Q1) (ECS-.327-12.5-13X)
• 1x Mosfet transistor, TO92 (Q2) (Supertex TP2104N3-G)
• 1x 3.3V Regulator, TO220 (REG1) (TI TLV2217-33KCSE3)
• 1x Temperature sensor, TO92 (TEMP1) (TI LM61CIZ/NOPB)
• 1x 7-segment 4-digit display (7SEG) (Lumex LDQ-N514RI)

Wiring of the incubator

The board has a 6 pin terminal that allows minimal effort in wiring all the AC part of the circuit.

• The 2 wires from the bulb socket go into LOAD.
• The 2 wires from the plug go into one of the AC IN terminal.
• The second AC IN can be used to attach a female AC socket. This allows to connect there a DC outlet to power the board.

Power supply

The board has a 2.1mm DC jack. The DC regulator requires an input of 3-12V DC.

Firmware

To install the firmware in your Arduino IDE, do the following.

• Copy the folder firmware/Fermento to your local Arduino folder.
• Copy the content of firmware/hardware to local Arduino/hardware.
• Copy the content of firmware/libraries to local Arduino/libraries.

Then, chose Tools -> Board -> ATmega328p on a breadboard. Choose the sketch Fermento from the sketchbook, and upload it.

In case you don't use the homebrew version, there is one line to comment out in the sketch to change the pin mapping.

In the Fab version, an ISP header is provided to burn the bootloader. The Homebrew version is lacking this, so a different board (such as the standard Arduino) needs to be used to burn the bootloader. In addition, an ISP-programmer is needed. An Arduino board can also be used to do the job.

Use it

Button1 and button2 control the incubation temperature and time respectively.

When button1 is shortly pressed the display switches to temperature. To set the incubation temperature, keep button1 pressed until it displays the desired temperature. The temperature regulation starts as soon as an incubation temperatures different than 0 is set. Note that if the incubation temperature is lower than room temperature, nothing happens.

When button2 is shortly pressed the display switches to incubation time (hours:minutes). To set the incubation time, keep button2 pressed until the desired incubation time is displayed. If you don’t set an incubation time, the incubation will never stop. The time goes up in increments of 30 minutes.

Pressing button1 and button2 together for a few seconds resets incubation temperature and time to 0.

License

2013 (c) Robin Scheibler, CC BY-SA 3.0.

Based on TokyoTime, itself based on SparkFun's BigTime.

The code uses the Arduino PID library.