Working with an Arduino Mega 2560 in Max

I am involved in a student project which uses some Arduino Mega 2560 sensor interfaces in an interactive device. It has been a while since I worked with Arduinos myself, as I am mainly working with Belas these days. Also, I have never worked with the Mega before, so I had to look around a little to figure out how to set it up with Cycling ’74’s Max.

I have previously used Maxuino for interfacing Arduinos with Max. This is a general purpose tool, with a step by step approach to connecting to the Arduino and retrieving data. This is great when it works, but due to its many options, and a somewhat convoluted patching style, I found the patch quite difficult to debug when things did not work out of the box.

I then came across the opposite to Maxuino, a minimal patch showing how to get the data right off the serial port. As can be seen from the screenshot below, it is, in fact, very simple, although not entirely intuitive if you are not into this type of thing.

One thing is the connection, another is to parse the incoming data in a meaningful way. So I decided to fork a patch made by joesanford, which had solved some of these problems in a more easy to understand patching style. For this patch to work, it requires a particular Arduino sketch (both the Max patch and Arduino sketch are available in my forked version on github). I also added a small sound engine, so that it is possible to control an additive synthesis with the sensors. The steps to make this work is explained below.

The mapping from sensor data starts by normalizing the data from the 15 analog sensors to a 0.-1. range (by dividing by 255). Since I want to control the amplitudes of each of the partials in the additive synthesis, it makes sense to slightly reduce all of the amplitudes by multiplying each element with a decreasing figure, as shown here:

Then the amplitudes are interleaved with the frequency values and sent to an ioscbank~ object to do the additive synthesis.

Not a very advanced mapping, but it works for testing the sensors and the concept.

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alexarje

Alexander Refsum Jensenius is a music researcher and research musician living in Oslo, Norway.