Temperature sensor

Projects General Guidance
1

I have been scouring the interwebs for some sort of hardware temperature display that provided at least 8 temperature sensor displays. This is a project for my computer, and although my computer has 3 onboard temperature headers these can only be monitored via software, and sometimes launching the software is not an option.

So my solution has been to look for a hardware solution, the only thing I could find was to purchase multiple individual probes/displays at $10 each, which would quickly become a $100 project, about three times what I would like to spend.

I have been looking for a way to do this with arduino, but this would be my first project and I am very much inexperienced with programming and the hardware side of arduino, so I am searching for help, the easiest and cheapest way to do this...

I did find This guy who had done exactly what I need, but his was not very accurate and some of my temperatures range barely 5℃, while others range 40℃, so it needs to be slightly more accurate, at least a ~3℃ accuracy...

If anybody can guide me through this, or an easier, more precise way, I would very much appreciate it! I would like at least 8 probes, but I understand there are limitations, and if 6 is the maximum for my price range of $30-40, then I will do that for now, and maybe just make a second unit later.. additionally, I would like to use 10K probes if possible... Those are what my motherboard is compatible with, and those are what I can find in a slim/flat form factor...

Thanks in advance!

~J

2

Get the requirements right.

in some places you want to have a high precision (0.1C) -> go for a DS18B20 digital sensor
in other places you could use an analog sensor (1C) -> go for an analog sensor.

if you want to monitor humidity in your PC too (it should be quite dry, -> DHT11.

by using a sensor that matches the requirements you can optimize the costs.

3

These are good. less than 50 pence each! and they give pretty accurate results.
LM35

4

I have worked for other projects with the DS18B20
it has a very good percision and you can connect all 8 probs using only one digital port.
There are also DS18B20 with a special pacage water proof.
You might have contact problems since the sensor is not within a metal cap.
I have build in the past metal caps for the DS18B20 using aluminnium tube and fiting the sensor inside.

JMaxado

5

Hi,
Look on eBay I got 5 x DS18d20 waterproof probes at less that £1 each, it's got good accuracy unlike the LM35, which I could never get right, there's a library for it too. In the passed I too made my probes with S/S or even plastic tubing, sealing the DS18d20 in with resin and heat shrink tubing.

Here's a pic, hope it helps.

Regards

Mel.

6

Please forgive me, as stated this is my first project... I am planning to use an Arduino Mini Pro 3.3V with a 3310 display. Regarding the thermal probes, I intend to affix them to the object being monitored with thermal paste or a thermal pad, I presume that will provide a sufficient thermal transfer for the unit...

It was mentioned that I can connect 8 of the DS18B20 probes to a single digital port, how is this done, are the probes addressed, do they require an interface board of some sort?

Regarding the programming of such a device, where would I start, does anybody have code that would be ready to go, or at least sufficient for a complete newbie... I am very proficient with computers/electronics for the most part, I just have not sufficient knowledge to start such a project without guidance...

I really do appreciate the assistance and the time taken for this.

Thank you,

~J

7

Remember , google is your friend.
Just search google there many pages with projects involving these probes.
On the DS18B20 library you will find examples.
First try to find it on your way, if you cannot find it I may help you.
Not sure if these probes, DS18B20, work with 3.3v.
You may consider changing to another model of Arduino.

8

It was mentioned that I can connect 8 of the DS18B20 probes to a single digital port, how is this done, are the probes addressed, do they require an interface board of some sort?

Each has its own address.

Regarding the programming of such a device, where would I start, does anybody have code that would be ready to go, or at least sufficient for a complete newbie... I

Try the "Multiple" example in the DallasTemperature library, should be enough to get you on the right track.

Not sure if these probes, DS18B20, work with 3.3v.

DS18B20 works fine from 3.3V

9

Okay, so far everything that has been provided is fantastic!!! I was able to obtain 10 DS18B20 probes for $20, which seemed to be a good deal.

So, I am going to say this to begin with, I know absolutely nothing about Arduino, though I am trying desperately to learn!

I really hate asking questions when I know the resources are available somewhere (I have been using search engines to find EVERYTHING since I was 14 - Started with YoMamma jokes- Yeah, that old!), but it seems finding the necessary resources for Arduino is a long and arduous task for me...

So, here is where I am at:

I have an idea of the Arduino I would like to use (after realizing that the one I had previously considered needs a $20 cable, and $15 breakout), so I have found THIS one that seems like it will work for my needs, though I could be incorrect...

The immediate issue I see is that it runs on 5v, and the 5110 LCD I was considering is 3.3v. I narrowed all of the text down for the display to be:

3 characters for the probe name, a space, and then 2 characters for the temperature, with a single space to separate the different types of devices. As in this example:

INT_T2
560_T2
560_T2
280_T2
(Empty Row)
LCO_T2
RES_T2
(Empty Row)
CPU_T2
BPM_T2
PCH_T2
VRM_T2
(Empty Row)

All I really see are 16x2, 20x2, etc. etc. displays. Is there something similar in style to the 5110 module, or that will fit at least (More is also fine) the above text, that will run on 5v for under ~$20? Additionally, I am not opposed to a TFT style of display, I just want to keep the budget as low as is possible, and I have already gone WAY over on the temperature probes, even though I got a great deal on them, My budget on probes was ~$5 or less... Though these will work out MUCH better I feel, even though it seems they may be more troublesome to get going (Based on what I have seen in forums).

So, If someone can just verify that the Digispark unit I have chosen is going to work for me, and possibly guide me in the direction of an appropriate display...

I do genuinely appreciate your help! The aforementioned advice has been fantastic in guiding me to helpful information regarding the DS18B20!!!

Thank you all,

~J

10

You know... After thinking about all of this, and considering that I MAY end up doing a couple of Arduino projects that I have been putting off for several years now (RGBW LED controller for some LED strips in my basement hallway, as well as a project to monitor doors being open/closed and being notified over the internet)

So, to that end, I am reconsidering my gripe about the FTDI adapters... I figure that the extra money I will spend on an Arduino with onboard USB, I will end up regretting it, because in the end it will end up costing me much more, for devices that I will (hopefully) program once and then let them sit and do their job...

The only thing I am still wondering about, however, is the display, ideally I would like something inexpensive that is at least able to display 10x10 (characters, lines, respectively). Again, my budget would be ~$20 ideally...

Again, thank you all, I will end up following the advice given and get this done!!!

~J

11

Why aren't you using your 3.3V Pro mini?
You can program it with one of these or these. Both around $2.
As for a 5V TFT display this will work.

edit* there is the Nano, no need for FTDI.

12

elac:
Why aren't you using your 3.3V Pro mini?
You can program it with one of these or these. Both around $2.
As for a 5V TFT display this will work.

edit* there is the Nano, no need for FTDI.

I opted against the mini because of the FTDI cable issue... I could not find one that was that cheap, everything I found that I could verify would work for this was going to cost me a good bit extra...

Additionally, I was not able to find a decent display that would work with the mini, so I ended up going withy a larger unit that supports a larger touchscreen display, and includes the shield to use it, my main reason, is that I think this will make it slightly easier in the interim, and provide hardware for a future project I am planning (Addressable LED controller), where the touchscreen would come in handy.

Most of the displays that fit my requirements were not able to interface with the smaller units, unfortunately...

I opted for THIS UNIT so that I could be sure to have compatibility. Hopefully I can get the display working, if not I will surely be back... Thank you to everyone that helped me, and even though I more than doubled my budget, I think this will be a fantastic temperature monitor!!! Especially given the ability to upgrade down the road if I need (want, more like) more probes later on...

~J

13

Okay, unfortunately I am back, and I think I may have made a huge mistake... I ordered the Mega 2560 and a TFT shield thinking it was the only solution for a display with the space for text I needed and the digital pins, however, I assumed the PWM pins could be used for the temp probes, and now I am not entirely certain, after having looked around it seems they are for output only...

Is this accurate? I saw "54 digital pins, of which 14 CAN be used as PWM, it never occurred to me that they might be output ONLY for controlling LED's or fans or something...

I apologize again for my supreme lack of knowledge on this topic, but after pouring over Google with a hundred different ways of searching 'PWM input', I only find people controlling fans and LED's...

Additionally, if they are for output only, what are my options at this point? I have already spent double my budget on hardware (to have it a particular way with 10 probes and display), and now I could wasted most of that on a 'solution' that is no solution at all...

The TFT display I am using has a touchscreen, is it possible to desolder one of the pins for that (if digital) and use it for the DS18B20 probes?

14

The PWM pins can be used as digital inputs.
Using the 3.2" screen and shield you have analog pins 0-15 free, which can also be used as digital inputs.

15

Analog inputs can be used as digital!?!?!? That would have been infinitely helpful to know weeks ago... It seems it is time for me to change my digital way of thinking with Arduino...

Thank you very much for easing my mind!