Serial Multiplexer Project

Mission

Build a serial multiplexer to combine signals from multiple devices into one RS-232 serial stream.

Background:

This was built for UMBC's Intelligent Ground Vehicle Competition entry. The robot needed a close-range emergency collision detector. I'd recently read about the MaxBotix (http://www.maxbotix.com/) sonar modules on the comp.robotics.misc newsgroup and thought they'd be a great sensor for the sonar system.

The MaxBotix units have multiple interfaces: RS-232, Analog, and PWM. I like the RS-232 personally. I think it's the most accurate way to pull data from the sonar modules, because you don't have to worry about potential signal losses from converting analog to digital, or timing the PWM signal accurately.

In order to cover all the sides of the robot, we needed multiple sonar modules. To make it possible to connect all of the modules to the computer, we needed to combine the data from all of the sonar sensors (two at first) into one rs-232 that we connected to the laptop controlling the robot.

Parts:

I used 2 MaxBotix sonar modules, a PIC 18F1320, an Olimex development board, and the CCS PCH compiler (C compiler for PICs).

Materials Used	Cost
MaxBotix Sonar Modules (quantity 2)	$40
Olimex Development Board	$16
Microchip PIC18F1320	$5

Up next: Design and Implementation -- click here to continue

project added: 6/11/2006

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