MySensors Mother/Daughter board system

This repository contains the PCB design files, 3D renderings, and software libraries to implement the MySensors mother/daughter board system described in this thread.

It's a mother/daughter board design using an RFM69 radio (though it would be easy to change it to an NRF). I have about 10 sensors I need to make and they're all similar, but not quite the same. This system allows be to mix and match what I need for each application. It's designed to be AC powered and uses a single case (see below) for all of them (~$3/apiece for 10).

The main board has the basic components and supports two daughter boards (roughly 25mm x 35mm) which plug into the side so the whole assembly is basically flat (leaving more room in the case for the switches, connectors, and LED's). An additional third daughter board can be used for small boards mounted perpendicular to the main boards (the sensor board below does that) or mounting over the top of the arduino.

The main board contains:

• 3.3V Arduino Pro Mini
• RFM69 radio
  • side mount for external dipole antenna
  • interior mount with enough space for a helical antenna mounted parallel or perpendicular to the board
• 5V->3.3V power supply
• digital signing chip
• flash memory chip
• input and output shift registers
• headers for a switch, LED, and piezo buzzer
• header for SPI (MISO, MOSI, SCK) pins
• 2 side mounted daughter board headers with inputs and outputs from the shift registers
• 1 top mounted daughter board header with pins from the mini including D3 (IRQ), D5 and D6 (PWM), A3, A4 (SDA), and A5 (SCL)
• all components are top mounted for easier soldering and a bigger ground plane for better antenna performance

Boards

Each daughter board header has 5V, 3.3V, ground, 3 input pins, and 3 output pins. I've designed seven different daughter boards so far.

• Valve/motor control board. I'm using this for articulated water valves for controlling leaks at the water heater, washing machine, etc. It contains a L9110 motor controller, LED, and valve open/closed sensors.
• AC relay board. I'm using this to control simple AC load switching (in my case, a recirculation pump). The board contains an opto-isolated AC relay with NO and NC terminals, 1 LED, and 2 sensor inputs with pull down resistors.
• DC relay board. I'm using this to control simple DC load switching (in my case, a triggering a garage door). The board contains an opto-isolated DC relay with NO and NC terminals, 2 LED's, and 3 sensor inputs with pull down resistors.
• Protected input board. I'm using this to trigger when external security cameras and motion sensors trip (they both operate on 12V signals). The board contains 3 opto-isolator circuits for triggering on 12V lines.
• Parking/RGB sensor board. This board contains pins for an ultrasonic distance sensor and an RGB (neopixel) ring. It includes 5V/3.3V level shifting for the distance sensor. This board must be connected to the 3'rd slot which interfaces directly with the Arduino pins because of the neopixel timing requirements.
• Sensor board. 3 sensor inputs with pull down resistors and 3 LED outputs with 1K resistors. This is designed primarily for water leak detectors. The rope leak sensor I'm using works better w/ 5V input and analog output so sensors can be fed with 5V or 3.3V and when connected in the 3'rd slot, they will output to the Arduino's analog pins.
• I2C board. This is simple small board that adds multiple I2C pins.

Here's an image of the assembled boards:

Ordering

The boards file contains the individual board designs (done in Eagle) as well as panelized versions. A single 10cm x 10cm panel contains 2 main boards, 1 each of the AC relay, DC relay, protected input, parking board, and I2C board; 2 valve boards; and 3 sensor boards.

Project Case

The boards are designed to fit inside a specific case (size and mounting holes) which can be found here. There are many options for ordering this case on AliExpress (various quantities and vendors). Searching for "105*65*40mm" will generally show them all.

Software

The lib directory contains a class for each board. Each child board class is constructed by passing it a structure from the main board class which defines which slot it's plugged in to. The boards (mother and children) all contain elements for manipulating their components (LED's, relays, sensors, etc) which abstract away the method by which their connected (call sensor.led[0].on() to turn on the 0'th LED of a sensor board) which makes writing the final sketches which use the boards very easy.

The software does depend on my arduino-core library classes.

Licenses

All the software in this repository is covered by the GPL-V3 license (see LICENSE-software).

All the hardare in this repository is covered by the CERN Open Hardware Licence v1.2 (see LICENSE-hardware).