# LMT86 and Arduino

## Temperature with an Arduino Uno and an LMT86 Analog Temperature Sensor – by Greg Bushta

The Datasheet from TI for the LMT86 has a chart with the corresponding temperatures in °C and a mV. I noticed that the number read from the center pin is 1/5 that of what is in the chart. I am powering the LMT86 with 5v from the Arduino Uno. I noticed that there is about 11mV different from one °C to the next degree. However, when the number read on the pin goes down the corresponding temperature rises. I looked at the number corresponding to 0°C, 2100, and the number for 100°C, 997. These represent freezing and boiling of water. I subtracted 997 from 2100 and divided the result by 100 to get the approximate difference per degree C that the mV number would be. The result was 11.03. So, I figured that for every rise in degree C starting at 0° I could subtract 11.03. I thought why am I multiplying the number read on the pin by 5 and then doing my calculations with 11.03. Why not divide 11.03 by 5 and work with the number read from the pin. 2100 divided by 5 would give me the number read from the pin at zero degrees, or 420 as my starting point. So, I take the reading from the pin and subtract it from 420 then divide the answer by 2.206 to get my degrees in C. From there I convert °C to °F with °F = (°C * 9/5) + 32.

I think It is fairly accurate since it is reading 380 and feels just a little on the chilly side in the room. After all it is mid-January and 2:45 in the morning. It is raining outside. There is a fire going in the other room. I am off to sleep.
– Greg

## (the next morning)

I tested the calculation with a piece of ice wrapped in plastic to keep the sensor from getting wet. The reading with the ice held upon the sensor was 426. That calcs to 27°F. So, that is not quite correct. Close but not quite right. I wonder if the correct starting number for 0°C should be 426.

Wouldn’t that be the correct way to do the measuring? Or, perhaps the scientific way? Get a starting number for zero degrees C and another number for a known temperature, perhaps boiling water. Then I could do the correct calculations. I would need to get the range and figure the steps per degree again. But my calculations would be much more accurate.

At boiling I got 212 on the read pin.
On ice I got 426 on the read pin.
Lets do the calculations with those numbers.

426 – 212 = 214
214 / 100 = 2.14
Boiling is 212. Freezing is 426. The difference is 214. From ice to boiling is 100 degrees, or steps. So, each step or degree is 2.14 on the pin read.

The LMT86 Sensor is hooked up
on the Arduino Uno with
+ pin on LMT86 is hooked to 5v
GND pin goes to Arduino GND
Data (center) pin goes to A0

``` int LMT86Pin = A0; int TempRead = 0; float voltage = 0; float Temperature = 0;```

void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
Serial.println(“LMT86 test!”);
Serial.println(“Testing the Temperature Sensor”);
}

void loop() {
// put your main code here, to run repeatedly:
Temperature = (426 – TempRead) / 2.14; // was 420 and 2.206
Serial.print(“The temperature is “);
Serial.print(int(Temperature));
Serial.println(“°C”);
Temperature = (Temperature * 9.0 / 5.0) + 32;
Serial.print(“The temperature is “);
Serial.print(int(Temperature));
Serial.println(“°F”);
delay(5000);
}

# ESP8266 devices from Adafruit and Sparkfun

## Learning and playing with the ESP8266

I went to the HackaDay SuperConference in San Francisco on November 14th and 15th of 2015.  What a fun event. They were having workshops.  One of the workshops was working with the ESP8266 unit.  It is a WiFi device that is about the size of a Quarter.  The one provided in the workshop is actually a redesign by Sparkfun.  It is the ESP8266 Thing.  I fell in love with it.  It is tiny and powerful.

In the workshop we learned to make an LED blink and tested a button.  Then we set it up to connect to WiFi, next as an access point.  While it was connected to the internet we used a mobile device app called Blynk to control the Thing.  I started thinking, “what else can I do with it?”

I took some more pictures after I put the little Huzzah onto a small breadboard and powered it with a LiPo battery.  It works perfectly.

While there is still a lot for me to learn, I was able to complete the workshop Arduino sketches again at home.  I asked for help from one of the guys on hackaday.io who also took the workshop.  I was missing a pull down resistor.  When I put the resistor on the Thing I was back in business.

(I certainly wish my MacBook Pro would stop autocorrecting hackaday into lackaday.)

Right before the SuperConference I went online to the Hackaday store (haha, I selected Learn Spelling.  That should take care of it.) and saw that they sell an ESP8266 breakout board with the Hackaday logo printed on the bottom.  I was so excited that I ordered two.  I didn’t notice that there was also an Adafruit logo also on the bottom of the board.  Adafruit makes quality stuff and has great tutorials.

## Going further with the ESP8266

I decided that I wanted to be able to set up one board as an access point with its own LAN and not connected to the internet.  The second board would be set up as a client that would connect to the first one.  As a test I decided having an LED on the first (server) board, and the second would have a push button to turn on the light of the first board.  I know, it is not very spectacular, but it is a start to getting things connected and talking to each other.

Right now, after many failed attempts and finally success, the two boards will connect to each other.  The button on the client board will turn on the LED of the server board.  I even tried it from 60 feet away.  I was in the house and it is raining outside.  I don’t know how far apart these two things can be, but I will see in the near future.

What can I see that these two little guys are capable of?  Perhaps controlling an ATTiny85 chip with a speaker like that in the Hackaday instruction that causes it to cuss, or operating a servo remotely to control a camera or a robot, or even having it remotely control an electronic lock.

So far, I am able to get one to issue the commands and the other to respond.  That was my beginning goal.  Have one set up as an access point and no connection to the internet, and a second one that would connect to the first to be able to issue commands, such as turning on an LED with the push of a button.  I am easily impressed.

One trouble I was having with Adafruit’s Huzzah was that I was getting errors.  I did a bit of reading trying to get the lookup terms correct.  One of the sites ended up saying for the guy to contact Adafruit and they would set up a replacement because the board was probably bad.  I thought I might have toasted it when I was soldering on the pins.  Further reading on a different site said that the guy found out that the FTDI cable through USB wasn’t providing enough juice to run the board all the way.  So, getting it to work properly required external power.  I used power on a breadboard and had no more trouble.  I was going to power the Huzzah with a LiPoly battery anyway, so now I am set.

The thread that told me about the USB cable with FTDI maybe not providing enough power is here.  The person posting the query and the answer is Hapax Legemenon.  I was very happy to see this post and had success when trying it out with a separate power source.  No more errors.  The main error I was having was that the Huzzah kept rebooting every so many seconds.  Even though it didn’t cost very much, I didn’t want to have a broken toy.

## In conclusion

I am having a lot of fun with these devices and the programming part.  I’ll be coming up with some ideas to include them in a mounted project that I can control from afar.

If there is interest I’ll post code when I get in here to edit this.  This is a long post for me and has been a long day.  And I want to test the connection again and make that LED turn on and off remotely before bed.

# Swearing ATTiny85

I added a push button so it would not swear constantly.  I got the speaker from a broken laptop.  The three AAA battery holder was from a friend’s ruined LED flashlight.

I had to learn to use an Arduino Uno to program the ATTiny.  It was fairly easy.

# Keeping Focused is proving to be difficult

I am in the middle of an Arduino, clock, humidity, and temperature project.  I also want to breadboard an ILI9341 display and an Arduino.  I should be finishing the clock before starting the other display.

Let me tell you about the clock.  Well, after I go clean and repair the heater.

I got the heater repaired.  There was a burned out wire connection bus.  I put a crimp splice onto it.  I think it goes to the heating element, or the fan.  You should see all of the LEDs and resistors to provide the fake flame effect.  Nice.  I’ll get to scavenge those later.  Now I have to hit the treadmill for a half hour.  BRB.

Now that I have that out of the way.  An hour of exercise today.  Half hour on the treadmill.  Earlier I used the Bowflex.

I bought a 20×4 LCD to use with the Arduino Uno.  I already had bought a DHT11 from Adafruit quite a while back.  In the same purchase I also bought a potentiometer.  Wow, that was just the one I needed to use to adjust the contrast of the LCD.

I soldered wires to the connection points of the LCD circuit board, stripped the ends and stuck them in the half-size breadboard.  After adding quite a few jumper wires, the potentiometer and a resistor, I had the LCD up and running.  I ran a few sketches to see how the display worked,   One was the ‘Hello World’ sketch.  Then I was off and running.  I wanted to change the count up numbers, seconds since getting power, into a real clock.  That took a little bit of formatting the lcd.print statements.

After getting the clock numbers set up I decided to add the DHT11 to display humidity and temperature.  I added the DHT, a resistor, and some jumper wires.  The data from the DHT comes with decimal points.  I didn’t care about 41.00% humidity.  All I wanted was the integer for the humidity and degrees.  (int) helped with that.  It was that easy.

Next I decided to learn how to add custom characters to the LCD.  I wanted to have the degree symbol, °.  I read a couple of web pages and figured it out without too much hassle.  However, I could not get memory slot 0 to display.  So I stuffed the ° into 5.

I thought, “what about buttons to adjust the time?”  First I added a button for the minutes.  It also needed a resistor.  Pressing the button increments the minutes that are displayed.  After 59 minutes the next button press goes to 0.  Also, holding down the button only increments the minutes one time.  Then I added a button for the hours digits.  If the number is less than 10 a leading 0 is printed before the time digit.

Just for kicks I decided to see what a graphic in four characters would look like displayed in the top right corner.  I tried to make the Skull and Cross Wrenches logo of Hackaday.

I’ve decided to mount this all into a plastic soap box.  I’ve had the Clinique For Men’s soap box for years.  Maybe thirty?  I took some measurements of the LCD.  Drew them on a piece of paper.  Taped the paper to the lid of the soap box and drew around it with a pencil.  I mounted a cutting disk for a Dremel tool into a battery operated drill.  I figured the drill would rotate slower.  If it spun too fast the plastic lid would just heat and make a melty mess.  With the hold for the LCD roughed out I used the file on my Swiss Army Knife to file and shape the hole.

The next part of this project is going to be soldering all of the parts onto a predrilled circuit board and add a bareduino.  I’ll have to scav the main chip from my other breadboard.  Then I’ll order some more ATMEGA328p chips.  I am waiting for some sockets from Futurlec to arrive.  I’d hate to burn out the chip when soldering the legs onto the circuit board.  If I am running out of time I can get one from Radio Shack.  There is still one in Ukiah.

I’ll run this up the flagpole and see if anyone salutes.  The next post should be about being finished with putting all of this into the soap box.

# PIR and electric lantern

I wanted to be able to have an electric lantern turn on as I entered the room. I decided to use a PIR sensor (Pyroelectric (“passive”) InfraRed sensor) as the detector. First I had to use a breadboard and the parts to get it worked out.

There is a second transistor on the breadboard as well as an LED and resistor. I didn’t use these in the project. They were left over from an Arduino project.

I am powering the PIR with 5v from a USB phone charger.  The three AAA batteries inside the lantern will light up the lantern’s LEDs.

A PIR has three pins.  DC+ in, Output, and Ground (-).  I connected the Output pin to the Base of the transistor.  At first I used a 2n3904 transistor.  This worked will when I as just using an LED on the breadboard as the light.  When I hooked up the lantern there was too much power and it bled through.

I put a guitar pick between one of the batteries on the positive side and put wires from the battery and the post where it was to touch.  It was like adding a switch.  The 2n3904 didn’t stop the electricity from flowing.  I had a 2n2222 on hand and ready that it can handle about three times as much and the 2n3904.

The schematic ends up looking something like this picture.

Perhaps I should be using a resistor between the PIR and the Base of the transistor.  So far the transistor doesn’t seem to get hot or mind.

Once I had the design working I had to solder everything together. I could not find an electronics board with all the holes pre-drilled. I knew I have one somewhere. I decided to use an old iTunes gift card as the circuit board. I drilled holes in it for the PIR’s pins, as well as for the transistor. I used short jumper wires to create the wiring I wanted. To connect the DC + and – pins of the PIR I soldered short wires to them and poked the other ends up through holes drilled in the card. I used a USB cable taken from a broken mouse and plugged it in onto the exposed pins I just created. For the fires running to the lantern I soldered two wires to the collector and emitter of the transistor and poked the other ends up through the card. I then soldered longer wires to those newly created pins.

Now came the tricky part. I took a small piece of an expired credit card and glued aluminum foil on both sides. After the super glue was dry I checked to see that the foil was not touching from one side to the other. I soldered the two long wires to the aluminum, one per side. Now I had a separator that I would be able to use inside the battery case of the lantern. I removed one of the batteries from the lantern and put this little piece at the positive end of the battery while I reinserted the battery. I think using a copper clad circuit board would have been easier to work with. You know the kind I mean, copper on both sides so you can etch your own designs with some acid. I think the closest store that might have this in stock, on short notice, is about 45 miles away.

I read information about the PIR from Adafruit. (www.adafruit.com) I love the NeoPixel LEDs they sell.  They are easily programmed and are very bright.

As soon as I heard about the Raspberry Pi 2 Model B+ I had to have one. I went to adafruit.com and got on the waiting list. Those things sold out fast. I received an email about a week later saying they were in stock. I immediately went online and placed my order. I could only get one. “One per customer.”, the sign said. Chris was going to have to wait.

In preparation for the new Pi I downloaded the latest raspbian and installed it to an SD card. Once I put the card into the new Pi I booted it up. Wow, was that ever fast! I expanded the disk space and set up the monitor settings. I kept it set to boot to console instead of X-window. Some of the stuff I do doesn’t need a desktop. I am happy with that.

I can set a VNC server and get into it with my iPad, or Mac.

Then I decided to share. I am hosting a Pi Day Introduction to Raspberry Pi at the Upper Lake Library on Pi Day. I have put out a few posters and the main library in Lakeport has put out a press release. I hope to get interested parties showing up.

I registered the Pi Day with raspberrypi.org and got contacted by Matt Richardson. He said he’s going to send (I have already received) stickers for the event. It feels so official. I hope to be able to start a user group out of this, or at least a programming group. That remains to be seen.

As for the stickers that Matt Richardson sent, I can’t wait to share them with the other Raspberry Pi enthusiasts. Thank you Matt!

# Been Busy

Went up to Eureka to work. The office is “repaired” and people can move back in. I loved reacquainting myself with co-workers. I work with a great group of people. They like each other, mostly. To save the corporation money, I stayed at my daughter’s. That was fun, too.

I loved being able to show three of my Raspberry Pis. One of them is set up as a camera in a Lego case. I actually love that one. I guess I should figure out if I can set up the Raspberry Pi 2 with the camera. I am having fun with them.

On the 14th, PI Day, I am doing a Raspberry Pi demonstration at the Upper Lake Library. It is on the corner of Main and Second. Maybe it will blossom into a user group. I would LOVE that.

I am glad to be home and able to relax (relapse). Listening to Floater. Repaired the vacuum. Tasting wine. Loving life.

# More Reading – HTML5, CSS3 and Javascript

I mashed on the code today a lot. Added HTML elements through Javascript code and changed the HTML interactively. I can’t believe how easy it really is.
I did run into a wall for a few minutes before retiring for the night. backgroundColor has a capital C in Color. When I couldn’t get the background color to change within a defined 400×300 rectangle I had to re-check the code. I was missing that C in two spots. What a relief to find that. It is always the simple syntax errors that cause the most damage.
Tomorrow is another day of working on the house, playing music and programming.
Today I tried my hand at crocheting. My stitches were way too tight. It took mw about six or seven times to get them loose enough. Trying to make a Cat Bus for Emily. I am working out the style of one of the legs.

Oh, since I can include code, here is the code from today. This first part is for the HTML part. The second part will the the Javascript.

var myButton = document.querySelector(“button”);
var whatColor = 0;
var body = document.querySelector(“body”);
var score = 0;

function myClickHandler()
{
score ++;
var output = document.querySelector(“#output”);
var divColor = document.querySelector(“div”);
if (score === 1)
{
output.innerHTML = “The button was clicked ” + score + ” time.”;
}
else
{
output.innerHTML = “The button was clicked ” + score + ” times.”;
}
output.style.fontSize = “50px”;
output.style.textDecoration = “underline”;
if(whatColor === 0)
{
output.style.color = “red”;
whatColor = 1;
myButton.style.color = “brown”;
myButton.style.backgroundColor = “#aaaaaa”;
body.style.backgroundColor = “#2222cc”;
divColor.style.backgroundColor = “#5555ff”;
}
else
{
output.style.color = “blue”;
whatColor = 0;
myButton.style.color = “#ff3333”;
myButton.style.backgroundColor = “#cccccc”;
body.style.backgroundColor = “#5555ff”;
divColor.style.backgroundColor = “#2222cc”;
}
}

Well, that didn’t work out quite well enough. The HTML stuff rendered instead of listed. I can fix it in the morning.
Using the code tag doesn’t work. Some stuff gets stripped out and some of the HTML gets rendered, and changed. I have read a few posts through google. I may need to install a plugin.

I ended up adding to Simple Custom CSS and having to force some inline styles to get the section showing code how I wanted it. I wanted non-horizontal wrapping and vertical scrolling, with horizontal scrolling if needed for long lines.
I accidentally hit publish which took it out of draft mode. Bother!