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1  Using Arduino / Sensors / Re: RTD temperature input stage problem on: February 19, 2013, 10:49:26 am
A pull-down resistor did the trick. Please feel free to use this circuit. Just give credit where it's due. If you have any modifications to it, please post here so everyone can benefit. This is the first complete RTD pt100 input circuit I've seen in the public domain which includes a current source and output-scaling. There are others out there which do different parts better, but not all together like this.



I don't read schematics that well.
Where are the wires to the PT100 and where are the pins going to the Arduino?

Thank you.
2  Using Arduino / Sensors / Re: amplifier for pt100 on: February 19, 2013, 10:47:57 am



So a bigger noob asks this question:

Where are the leads for the PT100 and the arduino input pins?

Thank you.
3  Using Arduino / Displays / Re: How to wire an mjkdz I2C board to a 20 x 4 LCD on: January 13, 2013, 12:10:20 pm
As far as the LCD spin out goes, I only put that there as I've not used a 20x4 display so wasn't 100% sure they were all identical. I'd guessed they were as the backpacks work on those two, but safer to have the OP make sure. ;-)

Hopefully he'll report back if it's worked for him. I know some people can get tremely frustrated when things don't work and get the 'it's no good, I'm fed up, it's rubbish' red mist. I have a couple of mates with low patience levels like that. smiley-razz

OMG (as the kids would say)!

I wanted to do things by the book (i have seen many posts about non-soldered LCDs, wink wink), so I ran the I2C scanner.

x20, and not x27! 

I wire it up using my old floppy cable, and the frickin' backlight comes on! 

I download the new I2C files and copy it to my library, copy tack's code, and  smiley-eek

tack wanted to make sure I knew how to fix code......ahahahahaha.  A few ; here and there and it was ready to upload.

Mama Pajama!  I could see some stirring in the LCD, so I gave the pot a few twists, and MONEY!  We have a working mjkdz LCD I2C backpack!

I am now troubleshooting the fact that my "R" in "FORUM" looks like this:

****
*
*
****
* * 
*  *
*

instead of this:


****
*    *
*    *
****
* *
*  *
*   *


I will mark it solved, since I can see clearly now the LCD.

Again, many thanks to all of your for your tips, expertise, and encouragement.
4  Using Arduino / Displays / Re: How to wire an mjkdz I2C board to a 20 x 4 LCD on: January 13, 2013, 02:10:02 am
Thank you to everyone for your suggestions.

I have been celebrating my birthday early smiley-mr-green , but will try them out tomorrow and report. 

I was looking at the photo and it seemed that the pins just lined up, but when I did that (using both an old floppy cable, and standard jumper wires), I got no backlight when I applied power to the arduino.  I assumed that the pot would be a single turn jobber, not a 22 turn.....I gave it a 60 degree twist left and right (because that's all it took on the ones I bought from my local chip shop), and got nothing.

And I saw the other posts about changing the constructor, and asked wtf they would do that and not just keep one standard way of doing it.  But that would take all the fun out of it, right?

And yes, sometimes I get that "it's no good, eff it, and chuck it into my toy box" attitude.  But before I do that, I check with the experts.

I finally got an answer back from the seller.  They sent me the docs.  Too bad I don't speak Chinese.... smiley-eek  They promised to send me the English ones asap.  I'm betting that I will have it running long before then.

Again, thanks to all, and I will report back.

 
5  Using Arduino / Displays / SOLVED: How to wire an mjkdz I2C board to a 20 x 4 LCD on: January 11, 2013, 11:06:29 pm
Sometimes cheap is not good.

I bought a 20 x 4 LCD and an I2C board from ebay

http://www.ebay.com/itm/300821305754

and

http://www.ebay.com/itm/130748113121



I have no pinouts.  The picture shows a 1-1 connection.  That does not work.

I don't have the technical expertise to test pins for output.  Can someone help me?

I know the 20 x 4 works ( and i have a few 16x2s lying around) and my Arduino Uno R3 works (I used the old breadboard technique).
6  Using Arduino / Programming Questions / Re: LCD Shield on Mega2560 versus Mega1280... on: December 07, 2012, 12:09:38 am
Warning!  Before you buy these things.

I have an Uno R3 running 1.0.2, and have wasted 10-20 hours trying to get it to work.  I can't.  The ebay reseller tells me it works under 0023 and 1.0.    So, I try it....No Bueno!

The reseller changed his description after I complained, now saying it only works on the Mega.

So because it will cost me more to send the fershlugginer thing back to China, and before reading this post, I buy a Mega 2560.

It doesn't work either.  I suspect that the shield pins are off. 

So I have a TFT paperweight. 
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