Rev. 0.2 5/11
Copyright © 2011 by Silicon Laboratories
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1. Kit Contents
The RF to USB Reference Design contains the following items:
Si1012 Energy Harvesting Wireless Sensor Node
EZRadioPRO
®
USB Dongle
ToolStick Base Adapter
3-foot USB extension cable
2. Introduction
The purpose of this reference design is to demonstrate an ultra low power wireless sensor, powered from an
energy harvesting source. This application is typical of systems which wake periodically to measure and transmit
results. Since it is powered from an energy harvesting source, no batteries need to be replaced for the life of the
system (life expectancy is greater than 15 years or 7000 mA-H) and the wireless node can be designed with a very
thin profile (battery height is 0.17 mm). The system consists of two components: a wireless Sensor node and an
EZRadioPRO
®
USB Dongle. The Sensor Node uses a Silicon Labs Si1012 wireless MCU. The Dongle uses a
Silicon Labs C8051F342 MCU and a Silicon Labs Si4431 radio.
The Sensor Node operates at 919.84 MHz and is powered by a solar energy harvesting power supply. When the
wireless Sensor Node is not transmitting data, the Si1012 wireless MCU can remain in a low-power state where it
only consumes 50 nA. The leakage current of the energy harvesting supply, when enabled, is approximately 3 µA
and is cancelled out by as little as 50 lux shining into the solar cell. This allows the energy harvesting supply to
power the system for approximately 7 days in a dark closet (in the ON position) or indefinitely if there is a periodic
light source that replenishes the lost energy. The system works both in indoor lighting (200 lx) and outdoor lighting
(10,000 lx) conditions.
Figure 1. Energy Harvesting Sensor Node
