This is my Bluetooth 4.0 to 900Mhz mesh network bridge. Here is a quick summary of what it will do. I plan to use this design as a development platform. There is plenty of room for code, and potential applications are starting to pile up. Possible applications so far are home automation, weather stations, boat monitor (I don’t want any repeats of the early morning fishing trip turned mid scuttle shuffles), and proximity light controller.

Features that should work no problem:

• Bluetooth 4.0 connection to phones and computers.
• Long Range Radio to communicate with other boards.
• Interface pins to turn things on/off, get user information from user, read out a display, or add sensors.
• On board weather station (temperature, humididty, and barometric pressure).
• USB or Battery powered
• 2 LED’s and 2 push-buttons

Goals that may work:

• Range of 1km
• Triangulation of Bluetooth source (Locate user with three nodes),
• Mesh networking where each node, or board, is connected to as many other boards as it can reach, and all messages are sent to all boards. Ideally if you have two boards that cannot communicate because they are too far away, they can still reach each other if there is a board in between.
• At least 6 months off a coin cell battery. (It will probably be more like 3 or 4, but 2 AAA’s should last a year minimum)

Honorable mention to some parts used :

• Texas instrument’s CC1200 Sub 1Ghz RF Transciever
• Nordic Semiconductor’s nRF51822 SoC (System on Chip) for main control and bluetooth connectivity11
• Humidity/temperature sensor (SHT21)  , pressure (MPL3115A2), and ambient light sensor (ALS-PT19)
• Texas instrument’s LM3670  step down converter to allow the 3.3 Volt board to be powered by 5 Volts from USB

 

Features planned for next revision:

• More output pins for an LCD/Touch Screen
• USB Control (Currently only for power)
• Stack-able headers to make adding a module as easy as connecting some pins.
• RF and Digital power plane isolation to reduce potential interference.