Heh. HMC5883L R00LZ

[Charles Shapiro]

Spent a few hours today HAX04ing up the next Amazing Arduino Project.  It'll feature an RGB LED which changes color depending on the direction the device points.  Propers to Adafruit for their most excellent sensor driver framework, which makes working with the HMC5883L compass chip  easy.

The final project will use a Pro Mini and have some fun pretties around it, but this is the prototype circuit loaded with a first draft of working code.  It changes colors at 72 degree ( five colors) intervals.  Experimenting with how many different shades and colors I can actually see clearly is next on the agenda.  I'm using PWM outputs on the Arduino which go 0-255 on each color, but so far all I see is white if I go full volume on the green and red and add even 10 units of blue.  Perhaps I should enlist someone who is less colorblind?

Picture ( http://tomshiro.org/compass_rose_prototype.jpg )

Demo ( http://tomshiro.org/compass_rose_72_degrees.mp4 )

-- CHS

[John Olthoff]

Probably technical, not due to colorblindness since that's usually due to the red and green receptor crosstalk. The blue should still have good contrast. Check the specs- the blue might require a lower voltage than the others.

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[bsan...@comcast.net]

I would select neighboring colors for high contrast so that the "jump" is distinct. You might also distinguish northern from southern with, say, reddish vs greenish hues.

Easier said than done, though! I look forward to seeing the finished product.

Bill





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[Charles Shapiro]

Ooh interesting!  Thanks for the input.  I isolated the colors to a header file and fiddled around with Open Office Calc for a whiles, trying out various color combinations for different directions. Using a spreadsheet was way easier than trying to type in hundreds of distinct numbers. In the end, I just went with full on // full off with the six distinctive additive colors in the RGB color wheel -- red, green, blue, cyan, magenta, yellow.  There's a distinct border between each color, but that only gives me a resolution of 60 degrees. The trade off seems to be between resolution of the compass and resolution of my color vision.  The compass is good for about 2 degrees according to the spec, but the largest number of colors I tried was, like, 36 ( 10 degree resolution ).  At that level, I could just barely perceive the color changes, and the subtle differences between colors in different directions were lost (e.g. the whitish mixing more red and green than blue was indistinguishable from the whitish mixing more red and blue than green).  My wife agrees with you that it looks best with just a few colors.  I probly should look again at the power vs lumens specs of each individual LED. I was doing simple mixes of the three on the assumption that they were all about equally bright.  My ideal vision is that it would change very subtly between just two colors in each quadrant, and maybe show a distinct hue every 45 degrees.

I'm in the process of moving the thing off my breadboard and onto an Arduino Nano. So far I have dead-bug-style connections for the LED, and I've gotten it to blink the 6 colors in sequence. The compass should be simple to connect.  Then I'll put the whole thing in a 3d-printed project box, add a white tissue paper rose to the top, and show it off (a "Compass Rose", get it?).  I've been taking pictures and videos of various stages -- this might be an Instructable in time.  The Nano has an FT232RL and mini USB connector on it, so I can still fiddle with colors even after it's pretty finished. 

Bummer that I can't find a Nano proto shield like this one ( https://www.adafruit.com/product/2077 ).  The guts of this thing is gonna have wires and connectors running every which way.  That might make it fragile, although I have applied heat-shrink generously.

-- CHS

On Fri, Nov 3, 2017 at 8:49 PM, <bsan...@comcast.net> wrote:

I would select neighboring colors for high contrast so that the "jump" is distinct. You might also distinguish northern from southern with, say, reddish vs greenish hues.

Easier said than done, though! I look forward to seeing the finished product.

Bill





-----Original Message-----

From: jolt...@gmail.com
To: decatu...@googlegroups.com
Sent: 2017-11-03 8:42:00 PM
Subject: Re: [decaturmakers] Heh. HMC5883L R00LZ

Probably technical, not due to colorblindness since that's usually due to the red and green receptor crosstalk. The blue should still have good contrast. Check the specs- the blue might require a lower voltage than the others.

On Nov 3, 2017 8:35 PM, "Charles Shapiro" <hooter...@gmail.com> wrote:

Spent a few hours today HAX04ing up the next Amazing Arduino Project.  It'll feature an RGB LED which changes color depending on the direction the device points.  Propers to Adafruit for their most excellent sensor driver framework, which makes working with the HMC5883L compass chip  easy.

The final project will use a Pro Mini and have some fun pretties around it, but this is the prototype circuit loaded with a first draft of working code.  It changes colors at 72 degree ( five colors) intervals.  Experimenting with how many different shades and colors I can actually see clearly is next on the agenda.  I'm using PWM outputs on the Arduino which go 0-255 on each color, but so far all I see is white if I go full volume on the green and red and add even 10 units of blue.  Perhaps I should enlist someone who is less colorblind?

Picture ( http://tomshiro.org/compass_rose_prototype.jpg )

Demo ( http://tomshiro.org/compass_rose_72_degrees.mp4 )

-- CHS

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[bsan...@comcast.net]

I make my own protoshields using protoboards with 0.1" hole spacing cut to fit. Use headers and sockets for the pins as needed.

There may be some pieces of the protoboard in a drawer, left hand side of drawer stacks in the eshop. Headers and sockets are in the parts bims above the drawers, left hand side.





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