CWA's Project - Kart DAQ

Hi all,

I'm new to the forum, I am also rather new to programming and electronics. I thought I'd post up a bit about myself and my (first ever) Arduino project plans, as I'd appreciate any general guidance available and a sharing of similar experiences with people. I also have some specific questions which I'd be very grateful to hear people's thoughts on.

I have basic electrical circuit/component knowledge from a physics A-level, I have recently read a load of Sparkfun tutorials online, and I have also recently purchased an Arduino Uno as part of 'the Franzis Arduino Tutorial Kit', which I have been using to get into programming.

These efforts are all with the aim of gaining enough knowledge to build a DAQ system for a kart, ideally within a few months or so. I would like to record various types of data with my system; accelerations, rates of rotation, GPS, steering wheel/pedal positions etc, but I am primarily interested in recording tyre temperatures. Plug and play DAQ options on the market to suit my needs could see total system costs reaching £1000+. Whilst I could afford this, I would rather use this situation as a chance to learn programming - something I've always wanted to do, and perhaps save myself some money along the way.

Anyway, my first question is not about programming, it is about hardware. I wonder if anyone has any experience with the Melexis MLX90614 non-contact IR temperature sensor? - Wiring and Test | Using Melexis MLX90614 Non-Contact Sensors | Adafruit Learning System. I have one on order, and doubt I will struggle to wire it up to my Arduino, but this statement from the previous link troubles me: "The MLX90614 has a fixed I2C address, you can only connect one sensor per microcontroller!".

I think I understand why this might be the case, but is there any way around this issue, allowing me to wire, say, 4 of these sensors up to my Arduino Uno using I2C? I would of course need each sensor's data to be sent to a storage device (I am using an R3 Ethernet/SD Shield at the moment), where each sensor's data is kept separated.

The only hope I have so far has been found in this university technical report - (credit to the listed authors) http://www.wpi.edu/Pubs/E-project/Available/E-project-042511-130958/unrestricted/2011_FSAE_MQP.pdf. The report claims to be able to use more than one sensor per MC by "daisy chaining" the sensors in line via I2C (see page 34, below Figure 27). Here is where my limited knowledge fails me; could this work? Let's say I daisy-chained my 4 sensors together, in the way described by this report, would this allow data from each of the sensors to be sent through my MC to my data storage device, with each sensor's data kept separate? I am skeptical because; of my ignorance; because of the Adafruit claim above that this is not possible; and because the system designed in this technical report appears to have never been tested to verify functionality.

I have been advised by another very credible forum to look into multiplexing. Has anyone here ever multiplexed with this specific sensors, and would you say it's the best way to go to achieve what I want to achieve?

Of course, as you can probably tell, I will have a long way to go to actually make this work, if it is even possible. But I would be grateful of either some reassurance that this can be done, or of any suggestions that I should go and find some different hardware.

Many thanks in advance

Had you completed reading the paper or had you read the datasheet you would have found that there is a way to change the I2C address of these devices.

Oh and yes, of course youi dasiy chain them. Read up on I2C.

Mark

Thanks for the encouraging response Mark Holmes

Some experience but with PIC
My Instructable

But, should be same experience with Arduino, or better. Just remember to read then reread the data sheet, especially the part about the field of view as there are no optics on the flat quartz optical window.

Ray

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