Havaxer™ 01 is the smaller of the two boards: five temperature inputs, one mains input, three relays, two triacs and one signal output, around a socketed PIC.

It is built on Microchip's robust PIC platform and designed around the PIC18F16Q40. Other 20-pin DIP PICs may work if their peripheral pin mapping matches, but that is yours to verify.

01 can be optionally fitted with an OLED. It has two built-in buttons, and an eBUS adapter wired via a UART interface.

It was originally designed to control a complete HVAC system with one circuit that can heat or cool.

The PIC MCU is not included - the socket ships empty. The PIC18F16Q40 can be ordered with the board, and then arrives pre-programmed with my example application, for demonstration and testing only. Otherwise, choose your own PIC, write your own application and program it yourself.

Status

Dimensions, renders, photos and the full measurement reports are on the Versions page.

Issue trackeropen_in_new

Specifications

Every capability below is explained on the Features page. The numbers here are what this model has.

The board is an industrial/consumer electronics manufactured PCB:

• FR-4, lead-free, green
• 4 layers, 1.6 mm thick
• 143 mm (+ 4 mm) x 160 mm
• height approx. 20 mm
• weight approx. 154 g
• room temperature 0 to +40 °C
• all components are RoHS compliant

Connections:

• PIC MCU socket (20-pin, DIP)
• PICkit ICSP header
• UART, PICkit compatible header (3.3 V)
• eBUS adapter to UART
• I2C display header (3.3 V)
• I2C QWIIC connector
• USB-C connector (power only)
• alternative power supply terminal (7-33 VDC, 7-22 VAC)

Inputs:

• 5x analog temperature sensor (NTC 10k)
• 1x mains optocoupler (250 VAC)

Each input has its own MCU pin.

Outputs:

• 3x mechanical relay (250 VAC, 10 A)
• 2x solid state relay - triac (220 VAC, 1.2 A)
• 1x driver (5 VDC, 100 mA)

Outputs are driven straight from the MCU pins.

Supplied as a bare board. No enclosure is included.

Terminals

Every terminal carries its own name and rating on the silkscreen. Mains terminals are on the bottom edge, low voltage on the top edge - see Terminals and wiring.

Screw terminals are 5.0 mm pitch.

Headers and connectors

Headers are 2.54 mm pitch.

MCU pin map

The socket is silkscreened pin by pin. All 18 I/O pins are used.

The board is designed around the PIC18F16Q40 - the largest-memory device in the 20-pin PIC18-Q40 family.

Power

Brought via USB-C or alternative power supply terminal. 3.3 V rail can also be powered via ICSP header during programming.

Some headers provide power rails.

Key components

What is switching your mains, and what the isolation is.

Known Limitations

Versions 1.0

• Using the UART port standalone (no eBUS) has a known limitation. The RX line is known to leak a tiny amount of current - enough to cause signal noise. To prevent this, simply wire the right pin of the EBUS ON header (H20) to the board's ground.
  Issue #25open_in_new

• The alternative power supply's printed range 7-33VDC / 7-28VAC is over-declared at the AC end. Should read 7-33VDC / 7-22VAC. On AC it is the peak that counts, and a 22 V RMS supply already peaks at 31 V.
  Issue #26open_in_new

What is not included

• no MCU - the socket is empty unless the optional PIC18F16Q40 is ordered
• no enclosure - the board is supplied bare
• no display, unless an optional OLED is ordered
• no temperature sensors, unless ordered
• no power supply and no USB cable, unless the optional cable is ordered
• no PICkit programmer
• no I2C pull-up resistors - positions are provided, deliberately unfitted, see I2C
• no schematic - the PCB layout PDF is published, the schematic is not
• no CE, FCC or UL marking
• no firmware support; the example application is for demonstration and testing

Installation and safety

This board switches mains. Read Installation and safety before wiring it.

Pricing, Order

Before shipping, each board is inspected and tested. If optional items are ordered, they are also inspected, tested and attached to the board.

Sold by a private individual, not a registered business. Import VAT and duty are already paid and included in the price - no VAT is charged on the sale, and no VAT invoice can be issued. Business buyers cannot deduct VAT on this purchase.

Shipping inside EU only.

Examples

This theoretical example shows what the Havaxer 01 was designed for: to control a complete HVAC system with one circuit that can heat or cool.