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What should I work on next (choose multiples if you'd like)?


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Discussion Starter #21
Upon looking at it some more I think large blocks would be more visible than "/" or any other character.
 

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Discussion Starter #25
Parts ordered:

1 arduino board
1 +-1.2 accelerometer pre-mounted on breakout board...nicely labeled and crap on the board
1 red on black serial lcd

total cost + shipping $100 (i'm still not a vendor...just giving you an idea)

parts i have: wire, leds (I think i might need a green one), resistors, solder, iron
 

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on other idea-

i really don't want to lose my clock, as i drive to work and such in my car.

what about throwing it in the ash tray? a bit harder to read, but still visable when you want it to be.
 

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Discussion Starter #29
^ sure

I was thinking of packaging it in a small plastic enclosure or something similar. I'm also toying with making it toggle on/off or making it dim by potentiometer (knob).

Expect lcd fitment and demo pictures soon.

(note that i'm trying to walk the fine line between advertising and just getting a feeler for what people like. So, if the mods have a problem pm me as I am considering becoming a vendor as soon as I get the prototype built. Maybe a one of small run groupbuy or something.)
 

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you could always have clint and TiC help you out if you don't want to be a vendor.

I bet he'd be willing to.
 

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Discussion Starter #33
Ok, didn't get much time to fiddle with stuff last night (or post), but things are looking good.

The LCD is fairly easy to hook up and relatively easy to send commands to. It has a splash screen that is configurable. So, if you wanted it to say "Hello, Dave" you could. It took me a bit to figure out what mapping it was using to display the box character, but once I got that it was fairly easy. The back light is program adjustable (this means that if I really wanted to get fancy I could hook up a circuit to the headlight on/off switch and automagically adjust the backlight accordingly.) It almost matches the interior red color. Its about 97% there, about like an omori gauge. The LCD is also a little bit larger than the clock.

The board programs nice and hooks up to a mac easily. When I do a final setup I'm going to have to solder in nice interconnects and such instead of using spare wire. Also, one needs to unplug the tx connection to the lcd when programming the board to prevent frying the lcd controller, so a pluggable connection would be beneficial.

I didn't get a chance to mess with the accelerometer at all. I figure I'll get to it after I read up on it sufficiently. Part of me wants to rush and have something duct taped to the dash for saturday's autox and part of me wants to take is slow and not mess things up.
 

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Discussion Starter #35
Just to clarify and keep me form getting banned.

I am not a vendor. I cannot sell you anything. I don't want to get in trouble. :D

I may be able to build one-run units (like 5 of them or so) out of parts you buy and I assemble. I am not at this point yet and we'll cross this bridge when we come to it.
 

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Discussion Starter #36
After reading about the accelerometers I think I may have bought the wrong one. Or rather, bought one I didn't need to buy. I got a digital/analog one that does 1.2g. I think a better choice would've been an analog 5g...would have saved $10 and had a better range of measurement. The analog works just fine with the board I got because it comes with a nice ADC in about 5 slots and will break the voltage signal into things from 0 to 1024 (digital numbers) or 0 to 5 volts. The accelerometer outputs either 3 or 5v max and is fully documented as to what means what measurement.

Using the digital signal on the accelerometer requires using PWM (pulse width modulation). This means I get a waveform (square wave) from the accelerometer and changes in the pulse width of that wave contain the data. So 0g is at a set frequency and as the width increases you go one way and as it decreases you go the other way. The unfortunate part is that you have to do some time calculations to get the number of pulses for per time to get the correct measurement.
 

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Discussion Starter #37 (Edited)
someone mentioned data logging:
http://www.sparkfun.com/commerce/product_info.php?products_id=752

I think you can just serial tx to this thing and get ascii text in a file on a SD card. This could be cool, but its $60.

I guess it could eventually be a full on gps/accelerometer track datalogger with a radio beacon and crap , but then i'd probably split it into different screens or something at that point.

To be totally honest, they sell a kit for GPS logging that is pretty nifty/easy to set up.
http://www.sparkfun.com/commerce/product_info.php?products_id=8237
http://www.sparkfun.com/commerce/product_info.php?products_id=8242
http://www.sparkfun.com/commerce/product_info.php?products_id=671
 

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Discussion Starter #38
More spam from me.

I got the accelerometer working. I'm currently using the pulse width modulation method. The reasoning is that all I need is 1 full pulse sample to get a reading. With the analog method you get a sampling and average over that to get a reading.

I'm still trying to figure out how to convert the pulse to the correct scale and i'm learning a bit about the lack of data representation stuff in this IDE.
 

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Discussion Starter #39
More thoughts:

1) self leveling - set 0g as whatever the reading is when you turn the device on. So if there is a little tilt wherever you install it it'll still make sense.

2) I'm doing analog. Its a) easier b) you can find more sensors in different sensitivities that are analog and c) i figured out how to easily map the values programatically
 

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Discussion Starter #40 (Edited)
ooh a video...

That's me tilting the accelerometer (the earth provides us with a 1g reference :) )

http://randomcrap.us/otherjustin/accelerometer_demo.mov (1.2Mb in size)

On my todo list:
-verify calibrations
-verify maths
-fiddle with update rate
-find an easy way(s) to mount the lcd in car
-self level/zero via software on startup
-add LEDS for forward and reverse acceleration??
-write program to parse raw serial output to a computer
 
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