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1  Using Arduino / Sensors / Re: PT100 sensor - help a beginner? on: April 28, 2013, 06:36:10 am
Yay, my sensor (finally!) arrived (that's what you get from ordering overseas via ebay...), and I got to play with it. I connected it straight to the analog pin of my arduino (well, "straight", I of course made a voltage divider for it, otherwise it wouldn't much make sense..) and run a program to read the values - and it worked!

A few minutes of math later I had a (very) rough temperature meter working. The normal 0-5V reference is way too much for the sensor (that at my current resistor values, outputs something between 0.44 and 1.39V when fed the arduino 5V). Luckily there were two facts:

1) I won't ever be hitting the 1.39V limit of the sensor, because that would need 850*C temperature. I'd at MOST be hitting 300*C which is about 0.86V)
2) Arduino has an internal 1.1V reference voltage capability.

By setting my reference to that 1.1V (on a mega you need INTERNAL1V1 and not just INTERNAL) I got a reasonably accurate meter just from the sensor and a couple of resistors, no need for op-amps or anything. Because I will be using this in a normal baking-oven project, I don't need that accurate readings. The cake won't care if the oven is at 225*C or 223.4*C... :)
2  Using Arduino / Displays / Re: EMBG12864J - Does anyone have any idea what this is and how to use it? on: April 28, 2013, 06:26:00 am
Sorry for taking so long, but I've been busy doing real life stuff (I do have a family with kids).

But, long story short, I now can use the display. I did .. err. a "bit" of research (read: n+1 browser windows open for most of one week, and about a mile of wire :)

Anyway, for future use if anyone else manages to get a hold of one of these, here's some details:

* It uses a KS0108 controller (so there's at least two libraries that you can use).
* Be sure to connect the contrast correctly: V0 pin to the wiper of a pot connected between Gnd and Vee(!), you do NOT connect the contrast to V+ in any way.
* There are TWO chip select pins.
* The friggin' thing as finicky as all h*ll with timing, if you update ANYTHING on the screen faster than 15fps DO NOT have epilepsy...
* Also note, at least my version really, really doesn't like drawing stuff at any extreme edges. I have to essentially use it as a 126x62 lines of display, because any graphic hitting any edge will make the display really blurry.

Other than that, it is a very nice display. Contrast is fine, brightness seems ok.
3  Using Arduino / Displays / EMBG12864J - Does anyone have any idea what this is and how to use it? on: April 07, 2013, 06:26:17 pm

I have dismantled and old washing machine that broke mechanically, so I believe electronics are functional. It had this smallish display in it and I thought I'd use it on some project. However, figuring out what the d*mn thing is turned out to be harder than I thought. No datasheets no pinout diagrams, about nothing. Only thing I could find was a 1-page PDF that had a list of different display types in the same family. That's about it.

The display is a 128x64 dots graphical display, about 4 inches diagonal. It has a 20-pin header without any markings. The pins 20 and 19 connect to the side (I traced the connections on the board) of the actual display to legs marked as K and A, so that's the backlight. Is has two additional visible ICs on the back (the other is a LM324 and the other is labeled F766100B01, which I'm not exactly sure what that is.)

Following texts are written on the silkscreen of the display:
(Front side, top of actual display):
EMBG12864J-01 VER A00
(under the actual display):
Kl sn102 94V-0

EMBG12864J-01 VER A00

Then it has a white sticker with:

If anyone has any idea about pinouts, what to use to talk to it, anything. I know 128x64 displays are quite cheap, but I'd like to use this one if it's at all possible. If not, my wife probably will make a dollhouse-flatscreen TV out of it smiley
4  Using Arduino / Sensors / Re: PT100 sensor - help a beginner? on: April 01, 2013, 09:43:07 pm
Thanks, yet again. Yeah, I was just reading the link you gave me, and the schematic doesn't look too difficult to implement. A bit more work, but, hey, if I didn't like tinkering, I don't think the Arduino forums were the right place to be in the first place smiley

Anyway, the opamp and the multiplexer were *really* cheap parts (both were in the 0.20-0.30€/piece category), so I ordered a few of those already. The rest are just a few resistors, caps and a pot that I probably already have. I have a few pieces of breadboard lying around so I'll first build it there and see if I can scourge up something more permanent after that. I'll probably first try without the amp/multiplexer (simply because they take time to arrive) and see if I'm able to do without.

I just wish there'd be something as simple as a TMP36, but with more temperature range... well, anyway. Thanks for the pointers.
5  Using Arduino / Sensors / Re: PT100 sensor - help a beginner? on: April 01, 2013, 02:48:09 am
Thanks again! I'll check out if I can find what parts I'd need.

But, you're correct. I would be okay with an "el cheapo" thermistor, but for the life of me, I can't find any online (ebay) that could handle 250C. They all seem to stop at 125C. I can't really by local, because... well, you wouldn't believe the prices if Id' show you a photo. I didn't believe them when I saw them with my own eyes. (for starters, the small metallic part in side a common jumper? 1,20€. ONE. JUST the metal. 0,80€ for the plastic. ONE 3mm ~3V standard red led? 3.50€. Yeah, I bought 20 bi-color LEDs for ~2€ via eBay...)
6  Using Arduino / Sensors / Re: PT100 sensor - help a beginner? on: April 01, 2013, 02:09:13 am
Thanks for the reply. Is that additional hardware strictly necessary (meaning it won't work AT ALL without it)? Or can I just connect the sensor straight to arduino and have it work, somehow. As I'm just tuning a small oven, I could go with ~5C precision quite well. Also the 0..400C range is a bit overkill, but hey, it was around 3€ so who cares. If I go to bare minimum, I'd be well if it measured 50, 100, 125, 200, 225 and 250C points, wouldn't really need anything more.

Before I read anything I just thought I'd connect it similar to a potentiometer and have it return some range of numbers with analogRead(). Does it not work that way at all and an amp/multiplexer is required? (if so, any pointers to what I'd need to get. Preferable cheap as the cost so far has been really, really low. (iduino nano at ~6€  is the priciest part...))
7  Using Arduino / Sensors / Re: PT100 sensor - help a beginner? on: March 31, 2013, 09:46:58 pm

Sorry to drop in to an old-ish thread, but my question seems highly relevant to this and I thought it's better to keep things together.

Anyway. I'm quite a beginner with Arduinos (and C/C++ in general), but I love tinkering with things and programming, so...

Long story short, I'm "pimping up" a toaster oven (yes, laugh if you will, I did), and I pretty much need a thermal sensor that can go up to 250C. I ordered a PT100+ (description said it is good from 0C to 400C) from ebay because they seemed to be dirt cheap for what they do.

But now that I read this, was that something I shouldn't have done? I mean, am I digging a hole for myself by trying to use that, or is that a viable thing to use just for measuring temperatures between 50C and 250C (maybe 100C-250C, haven't decided yet)? I'm looking for 1C accuracy, I don't need anything more, probably 5C would be ok.

Do you have any advice of what I should do when using that, or do you have any examples of what I should've bought instead that would be easier to use?

I thought that I'd just analogRead() that sensor (connecting it to 5V and GND also, I'd guess) and figure out what temperature is what reading and go with it. Would that not work?
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