A project log for LoFi

LoFi is a very low cost ($5), small, auto-transmitting module. Preassembled and preprogrammed. Simply attach to your appliances or projects!

david-cookDavid Cook 09/17/2014 at 02:590 Comments

The gateway listens to one or more senders and passes the data to a PC, or via WiFi to the intranet/Internet. This allows you to collect data locally or with a server.

The gateway consists primarily of an Atmel ATmega328 microcontroller that reads the 433 MHz receiver and writes to the FTDI serial cable and CC3000 Wi-Fi board.

Below you'll find the schematic. It begins with Schottky diodes for reverse battery protection and to allow multiple power source to be connected at the same time without affecting each other. This is followed by PPTC self-resetting circuit breakers for overcurrent protection. Finally, a Zener diode provides overvoltage protection. Because most people will only own one gateway, the extra cost of those protection parts is not a significant amount compared to an overall system.

Notice that most of the pins are not connected to onboard components. Because the purpose of this board is to route messages, most of the pins lead to external connectors. Many spare pins are available, as this chip was selected for its speed, RAM, and surface-mount package.

You can examine the PCB and Gerbers in the LoFi-PCB-Layouts.