Odyssey Personality – Proximity Detection

Introduction

This personality demonstrates proximity sensing by displaying IR light reflectivity measurements every second in the smartphone app. The data gives indication of accurate distance of objects within 18 inches above the Odyssey kit. Buttons are used to start and stop the distance measurement process. The same device can be configured for more complex sensing for interpreting gestures for user interfaces.

How To Use

Press the start button and note the number in the Autonomous display window at the bottom of the smartphone app. Move an object (or hand) up and down directly over the device (centered in the black o-ring). You will see the number getting updated every second. The number is lowest at 18 inches and above, where the detection distance tapers off (value ~250 – 350). When closest to the device the number is typically above 12000 (decimal). The numbers are repeatable for any given distance.

Users should press the stop button to avoid having the device continue the measurement process when done evaluating the personality.

How It Works

The SiLabs Si1147 device can be configured to use up to 3 IR LEDs (for complex movement detection), measuring reflectivity with built in ADC converters. The device is capable of subtracting out ambient light to get accurate readings in various lighting conditions. LED power, modes and the process is configurable via internal registers. This personality utilizes a simple single node (IR) implementation by setting up registers with configuration values via the I2C interface. The start and stop buttons initiate and terminate the measurement loop.

More Info

Requires minimum firmware v1.1. If needed, see the software download page.