Schematics have been drawn using Eagle 8.3.1.
This board contains the AC/DC converter, the relays and the connector to the wall housing.
This board holds the microcontroller and the WiFi to UART bridge.
- Single pole 16A relay with 5V coil
- BD135 NPN bipolar transistor
- 1N4007 rectifier diode
- 15pF ceramic capacitor
- 100nF ceramic capacitor
- 10uF electrolytic capacitor
- 10uF tantalum capacitor
- 5V 2A AC/DC power supply
- 160ohm 1% resistor
- 330ohm 5% resistor
- 470ohm 1% resistor
- 1Kohm 5% resistor
- 1Kohm 1% resistor
- Fuseholder
- Fuse
- 2-pad terminal
- 4-pad terminal
- Atmega328p microcontroller
- 3.6864MHz crystal
- 3.3V LDO
- WiFi to UART bridge
- 4-pin PCB male connector
- 4-pin PCB female connector
- 10-pin PCB male connector
- 10-pin PCB female connector
- Day trimmer : resistance variation from 50 to 110ohm.
- Night trimmer : resistance variation from 0 to 60ohm.
- Radiator water start thermistor : resistance variation from 580 (+80°C) to 900ohm (-20°C).
- Outside thermistor : resistance variation from 340 (+40°C) to 480ohm (-10°C).
Microcontroller uses a 3.3V precision voltage reference for the ADC module to gain more precision with small variation signals. All voltage dividers must be calculated as the highest variable resistance value results in a 3.3V maximum voltage on the ADC pin.
AC/DC converter inrush current is 40A for less than 500us, so a temporized fuse is needed to allow the board to boot.
AC/DC converter maximum input current is 150mA @ 240V, but due to enormous inrush current a big fuse must be used. A 250V/2A fuse has been chosen because this is the fuse used on the VTX-214 demo board (http://www.farnell.com/datasheets/1878969.pdf).
Install avr-gcc to build the microcontroller firmware.
Go to Software/Microcontroller_Firmware directory and type the following command to build the firmware :
make
File Boiler_Controller_Firmware.elf will be created.
You need to install avrdude to access to the programmer.
Firmware can be burnt to the microcontroller memory by connecting an AVR ISP programmer to the controller board ISP connector and typing the command :
make flash
You can override the PROGRAMMER_SERIAL_PORT environment variable with the serial port your programmer is connected to.
You need to install libmicrohttpd library before building.
On Debian/Ubuntu system, use the command sudo apt install libmicrohttpd-dev.
To build the web server, go to Software/Web_Server directory and type make.
Go to Software/Web_Server directory, build web server then type sudo make install to install server and init script.
You can use sudo make uninstall command to uninstall the server and all related files.