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Topic: SDA/SCL for a color sensor (Read 47 times) previous topic - next topic

flagss

Hi,

I'm trying to use a RGB color sensor (https://learn.sparkfun.com/tutorials/isl29125-rgb-light-sensor-hookup-guide) with the SDA/SCL pins.
The problem is that I need to connect two sensors with only one arduino. Is it possible to do it, since arduino has only one SDA/SCL connection? How can I do this?

Peter_n

That chip has just one I2C address and it can not be changed.
You could use a multiplexer, there are a number of ways to do that. With a special chip or with a logic chip, or with a mux chip.

Google for: arduino i2c mux
and click also on Images for some examples.

According to the datasheet:
The device identifier bits of ISL29125 are internally hard-wired as "1000100".

Headroom

#2
Nov 16, 2014, 02:42 pm Last Edit: Nov 16, 2014, 02:44 pm by Headroom
I agree with what was said above, however, just for reference, the Arduino Due and the Teensy 3.x boards have 2 I2C busses.

You can use a 74HC4067 to multiplex nicely with the color sensors. Miltiplexing several devices that have the same I2C address is described very well in this document:
http://www.egr.msu.edu/classes/ece480/capstone/spring13/group08/documents/dan.pdf

The chip is available in a DIP package, which lends itself nicely to breadboarding.
http://trippylighting.com

http://ledshield.wordpress.com/

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