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1  Using Arduino / Project Guidance / What kind of LCD is this? on: May 12, 2013, 10:33:01 pm


I need a white backlit LCD that has 1 character (numerical is my focus) - aprox. 1" tall by .3" wide

I completed my project using a LED 7-segment display : http://forum.arduino.cc/index.php?topic=163197.msg1227681#msg1227681

However I am finding it is FAR to bright at night time- and barely visible during the day time...

The Trailtech vapor gauge i have is perfect- in the day time the black text appears fully readable, and at night time it has a nice dim white glowy backlight.

Any other suggestions welcome too... I know I could put a dimmer on the LED-7 seg. but I figure it'd also be nice to have this display match more closely the Vapor gauges.

Thanks!

edit- something like this but backlit:
http://www.alliedelec.com/search/productdetail.aspx?sku=70127425#tab=overview

And can i run that via the Arudino?
2  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 03, 2013, 09:18:59 pm
Thank you everyone!!! - I uploaded a updated version of my diagram to the OP. And also- check this out:



I am going to tweak the software a bit more to just stay blank in between gear shifts.

Other than that- this is ROCK solid, displays my gears accurately even at high RPMs.

Current code for those interested- http://pastebin.com/iGiK8iQy
3  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 02, 2013, 09:49:47 pm
Get 100Ω (brown-black-brown) resistors - or my head will explode.

"How can I test that the resistors are working?"
The only way to KNOW is with a voltmeter.
+5 to CA, one lead of one resistor to any segment (cathode) with the other lead to Gnd.
There will be approx 1.5V across that resistor.

If the "spare" LED is a blue LED, you can use that.
If the "spare" LED is another colour then it will have a different forward voltage and skew the results.


Sounds good thanks- yeah I was expecting that the spare would have to be a blue one, and I figured it'd have to be tested with voltmeter.

I'll check this out tomorrow. THANK YOU everyone.

Hopefully this solves the issues I was having initially w/ the analog input voltage being skewed once plugged into my bike.
4  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 02, 2013, 07:42:44 pm

You have to connect the CA to +5, and NO, doing so will NOT "overvolt and damage them" - unless you don't use a resistor!
When the LED is ON it's forward voltage is "3.5V"
So, the balance of the 5V will be across the resistor - 1.5V
That 1.5V across the resistor will determine the LED current
1.5V / 100Ω = 15mA


PERFECT i am starting to understand! Thank you for this confirmation, i had just read this:

http://answers.yahoo.com/question/index?qid=20100308024927AAg0UQI

And now I am going to put a 102 ohm resistor (brown - black - red - gold) [right ? hehe] on each ground wire for this display.



zzzz.. think i read this wrong- 4band vs 5 band resistors :/  guess brown black red gold is actually 1000 ohms lol

Looks like ill have to get to radioshack for some 80-100 ohm resistors...

How can I test that the resistors are working? Should i just use a spare LED? I don't want to fry a segment on this display...
5  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 02, 2013, 07:26:27 pm
Grumpy_Mike,
pcguru has an Uno (it's there in his big darned PNG), there's 5V available on it - which I noted in my Reply_#37: "Anyway, you should have the CA wired to +5."
He was putting the 7-segment's CA to 3V in the belief, howbeit mistaken, that that would obviate any need for resistors.



And this 100% true- however, I still don't understand why i would need to move them to the 5v+ pin... this would overvolt the led's and damage them.

I understand now that LEDs once "lit" could essentially drag more current than they OR the system is made for... and so we put resistance inline to protect from that possibility.

Since in my situation the 3.3v (or 5v if I'm given a solid reason why) - see below ... line is powering a CA 7-seg. this to me means I could put a resistor in ONLY that + voltage line because this is the source voltage, the others (digital pins) just act as grounds.


Anyhow- I got my 9v regulators today, I just soldered them up but I ran out of daylight to go test this... i'll check it out tomorrow evening and report back- hopefully with better results smiley



I think i understand why a common resistor doesn't work now too:
http://www.edaboard.com/thread146902.html

http://arduino.cc/forum/index.php/topic,17251.0.html
6  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 01, 2013, 05:22:24 pm
Quote
In testing everything works 100% so I am not exactly sure why I need to add more components.
Because you are not testing it enough you are just going off functionality, this is not good enough when dealing with hardware.

You have to make sure that you are not stressing the components and that it will continue to work and not fail prematurely.
Read this:-
http://www.thebox.myzen.co.uk/Tutorial/LEDs.html
Anything you don't understand I will be happy to explain, anything you disagree with, then take up a new hobby.

Quote
really was aiming for super simple lol
Super simple designs are good but they need to be right, repeatable and work under all reasonable circumstances.


I am not disagreeing- I am totally ignorant with most of this stuff.

I don't however feel that this needs to be repeatable- Id just like to get it working for my bike, don't really care if I could mass produce it or not.

But regardless- I'd like it to last- so if resistors are necessary than I wouldn't argue about that.


Two things-
What is meant by "mux'ing"?

Yes the LEDS are blue- I am using this: https://www.sparkfun.com/products/9191
-These are running at 3.3v- but am I understanding now that they could pull 3.5 somehow?


7  Using Arduino / Project Guidance / Re: motrcycle turn signal on: April 30, 2013, 08:48:48 pm
Multi meter is easy :> See the big "V"

Turn it to the "20"

lol Okay a pro should chime in here that's all i know :>
8  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: April 30, 2013, 08:40:47 pm
Radioshack didn't have a 9v regulator in stock (I thought I had one, turned out it was a 12v :/) so I am gonna place and order and wait a few days...

As for the resistors and LEDS- reading about it- I am still not sure how this applies/works with a common anode 7 segment display- should i place a resistor in the 3.3v line?

In testing everything works 100% so I am not exactly sure why I need to add more components... (really was aiming for super simple lol, i am a web developer, not an electrical engineer afterall lol)

The arduinos 3.3v is the exact voltage the 7 segment requires to power it so I figured my input voltage is already clean, i don't need to adjust it. I understand that voltage changes can greatly affect the current draw from the led- but again, there isn't any change, just 3.3v...
9  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: April 30, 2013, 06:28:55 pm
Quote
I had it plugged in for like 20 seconds and then when i touched it on removal it was really hot...
How about those missing resistors to the LED display?

I don't understand why these would be necessary (is it just a best practice?)- its common anode so its just one 3.3v power source and then grounded lines - when not grounded they throw 3.3 volts. Seemed straight forward enough- and in practice, is working perfectly.

Regardless of whether the 7 segment display is connected (and i mean ANY of it) the voltage readings I get when the arduino is plugged into the GPS are the same... so this has nothing to do with it.

10  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: April 30, 2013, 04:38:10 pm
Quote
at 14.5 volts the 328 chip actually scorched my finger a bit which was surprising.)
Very surprising.

Is that sarcasm or amiright that this shouldn't have been the case...

I had it plugged in for like 20 seconds and then when i touched it on removal it was really hot...
11  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: April 30, 2013, 01:53:21 pm
Ah Thank you for this- I did not see Dougs post above and probably would have missed it all together if you didn't mention it.

I am power via the barrel jack HOWEVER I have a 5v regulator inline PRIOR to it- because I thought I'd aim for safer lower voltages (vs the 14.5 the bike throws).

As he said though- this is too little and could be causing strange behavior- I am going to wire in a 9V regulator that I have and see if that fixes it... hopefully that won't run too hot (really don't like it getting hot, at 14.5 volts the 328 chip actually scorched my finger a bit which was surprising.)

I'll post back here once I've tried this again w/ a 9v regulator.
12  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: April 30, 2013, 06:52:24 am
Well there is this whole thread:

http://www.svrider.com/forum/showthread.php?t=184545

You'l see "TeeRiver" did a different version of this (far prettier haha).

Pulled from http://www.svrider.com/forum/showpost.php?p=2967561&postcount=38

Quote
Inside the ECM is a 1k resistor pulled up to 5v. If the 1k internal ECM resistor is proper, then a 1k ohm external load will voltage divide 5v down to 2.5v. If you don't see 2.5v then start looking for a series resistor inserted somewhere on the Pink wire to the ECM.

You can also test the gear position sensor resistors individually by disconnecting the sensor, then measure resistance between sensor Pink, and ground Black/White. Should see:
1st: 374 ohms
2nd: 547
3rd: 1k
4th: 1.82k
5th: 4.6k
6th: 10k
N: open circuit.

FYI- there aren't any extra resistors inline here I've checked, just the 1k in the ECM and then the list above.

Perhaps there is a way to calculate this?

I'll give some readings:
With Arduino ConnectedWithout Arduino Connected
11.341.36
21.811.76
32.482.57
43.223.23
53.754.11
63.844.52
Neutral3.894.97


All of this said- I reprogrammed the arudino to look at the "On and Plugged in" numbers- that is the closest I got - but it displays 3 for First gear, 4 for 2nd gear, and N (Neutral) for all the rest... as if it is STILL not seeing the same voltage my multimeter is reading.

My old laptop isn't working with a batter- im half inclined to setup the duino with a LCD and have it print voltage readings and then just program for those numbers....

As for transistors and resistors... I have a bunch of resistors- this whole kit http://www.amazon.com/Arduino-Sidekick-Basic-Kit-Version/dp/B007B14HM8/ref=sr_1_1?ie=UTF8&qid=1367321842&sr=8-1&keywords=arduino+sidekick

And a few other things laying around. Again- really wasn't anticipating a complicated project.
13  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: April 29, 2013, 08:29:44 pm
Quote
So what is the verdict? What is the solution for this?
I can't think of any reason this is happening.   That's why I didn't answer before...   Maybe figure-out a different way of detecting gear selection?


I don't know why the gear indicator output would be high impedance, yet this is the "obvious" cause of what you are seeing.  (Unless it's not really an "output".)   

Because of it's very-high impedance, the Arduino's input shouldn't affect anything it's connected to, unless the voltage is greater than 5V, or negative.  (Internal protection dioes start conducting when the input goes nevative, or above the power supply voltage.)

Are you sure you have 5V powering the Arduino?   Are you sure the gear-output voltages are not negative?

An op-amp buffer circuit is the usual solution (to increase the input-impedance, or decrease the output impedance).  But, the Arduino already has very-high input impedance.

Quote
"The ADC is optimized for analog signals with an output impedance of approximately 10 kΩ or less"

Extract from Section 23.6.1 of Atmel doc8161.pdf

...R
That means that the output (source) impedance of whatever is driving the ADC input should be less than 10K.  The Arduino's input impedance is much greater...  The spec sheet (page 377) says 100 Megohms minimum.


And yes- i am sure i've got a 5v power for the Arduino- tested that a few times, its a V regulator from radioshack... solid as a rock at 5 volts.

Thanks also for the op-amp suggestion, i had read that elsewhere... something new i don't know about haha smiley
14  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: April 29, 2013, 08:27:48 pm
Great info on a few of those-

"Attach a 1k-100k resistor to ground on the floating pin and repeat the test. "

This is what I was *guessing* i'd need to do- but just so I understand this correctly- This implys that I cross my signal and ground wires, with a resistor?

Please excuse my noob understanding of electronics- I thought I'd just be hooking a couple wires up to get X voltage- the impedance stuff has me baffled.
15  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: April 29, 2013, 07:11:35 pm
So what is the verdict? What is the solution for this?
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