SHT15 Humidity and Temperature Sensor - SHT15 Breakout

Hey guys I have this precision temp/humidity sensor arriving tomorrow and I was hoping to be able to use it with the Spark Core so can send its readings over the web to be logged and graphed out.

Usually I just follow the Adafruit setup guides with an Arduino Micro and I’m good to go. I’m assuming that I’m going to need help getting this working with the Spark Core since its not fully Arduino compatible.

Here is the data for this sensor if anybody wants to take a look and let me know what I’m up against here.

2 factory calibrated sensors for relative humidity & temperature
Digital 2-wire interface
Precise dewpoint calculation possible
Measurement range: 0-100% RH
Absolute RH accuracy: +/- 2% RH (10…90% RH)
Repeatability RH: +/- 0.1% RH
Temp. accuracy: +/- 0.3°C @ 25°C
Fast response time < 4 sec.
Low power consumption (typ. 30 µW)
High precision sensor at low cost
Leading CMOSens Technology for superior long-term stability
Dimensions: 20mm / 0.8" x 20mm / 0.8"
Weight: 1.3g

Sensor Datasheet
Example C code
Wiring Example
Bilder Example
Git Hub


RWB, I found a more recent and better arduino library for the SHT15 here. It begs to be cleaned up a bit and it uses bit-banging, much like the DHT22 but it’s workable. I don’t have an SHT15 but I fixed the code so it compiles and put it up on my github. Let me know if you need any help. :smile:


@peekay123 Thanks Alot! Looks like it will at least get me up and running quickly.

I’ll report back with my experience.

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RWB, sounds good. I was I was rich like you so I could afford them fancy sensors! :stuck_out_tongue:


@peekay123 Yea the that sensor is crazy expensive indeed. I ordered the cheap temp chip also just to see how they compare when it comes to accuracy.

When the heater runs 24/7 during the winter the air gets real dry and that causes my skin to start itching. I finally bought a decently sized humidifer and started running it non stop and it keeps the air humid enough that my skin doesn’t get dry which makes life a lot better. So I’m wanting to track how much the humidity changes when the run the humidifier vs not running it. I bought the more expensive and accurate sensor simply because I figured it would give me less hassle getting it up and running, so hopefully thats the case. :smile:

RWB, I have some cheap(er) DHT22’s that are SUPER easy to get running, especially with the code posted on this topic (at the bottom), FYI :slight_smile:

Sensor arrived today.

I copied @peekay123 code from Github and loaded it up.

I opened up the Serial Port to see what it was spitting out but its garbage. The same data gets spit out regardless of if I pull the SCL or Data lines so I don’t then the Spark Core is reading anything coming in.

I see somebody else has a SHT15 sensor up and running on the Spark Core. I’ll see if I can get that code from them instead of banging my head against the wall trying to figure out something I really don’t understand :smile:

Did you change these lines:

#define dataPin  10
#define clockPin 11

to this ?

#define dataPin  D0
#define clockPin D1

@BDub :smiley: Of course I didn’t change that :smiley: I learn something new every day.

After changing the Pin data it started spitting out accurate data. :blush:

I updated the Temp to only show 3 digits total, so its 75.5F instead of all that extra garbage.

I had to change the sampling time from 2 seconds to a minimum of 5 seconds to get the Serial data output to work correctly. Now I have it spit out the data every 30 seconds. I remeber reading that the sensor needs at least 2 seconds before updates.

I added code to make the blue LED on the Spark Core to flash 2 times every time it updates the temp & humidity data so I know its working once I start sending the data to the web.

Now i’m going to have to roll this up with @BDubs watchdog code to make sure the dam thing stays connected to the web 24/7.

I guess I should post my code on Github and provide the link. That’s something new to do.

Next I will follow the instructions on how to pump this data to Google Docs Excel Spreadsheet with graphing.

Thanks for the help guys! @BDub & @peekay123


Good work @RWB! :smile:

Speaking of my watchdog code… I was doing some work tonight with those nrf24L01 radios and while I was waiting too long to open my serial monitor and setup the port… my Core was resetting and then breathing Red! I’m like WTF!!! Who rolled this change out already?? lmfao… then I realized I was working in the core-firmware directory that has my watchdog changes. I was REALLY confused why it was resetting on me, but because it was breathing red I figured it out pretty quickly.

SHT-15 Temp and Humidity Sensor for $10. I paid $40 for this a Adafruit.

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I have been using this setup for about 20 Days now and it works great.

I have just been logging temp data to a Google Drive Spreadsheet that is updated every 60 seconds. This data is logged and graphed live for later or live review.

Today I hooked up a Digole 1.8" OLED Color Display so I can see what the temp and humidity readings are at any given time. I didn’t do anything fancy yet as you can see in the picture but I plan on making it look better and display more info.

I would ideally like to have the display show local outside temp and humidity pulled through the spark from the internet. Maybe sombody could help me with that. Then I could scroll inside & outside temperatures.

Also maybe some arrows to show if the temp is trending up or down.


hello, I am super new to this. I tried adding the code in the IDE for the SHT15 but I get all sorts of error. No idea what I am doing wrong. Any help is greatly appreciated. See attachment

@davidrtk Try including #include "application.h" at the top of your sht15.ino & sht1x.h code.

That has to be added to all the new sketches to get it to compile.

thanks RWB, that fixed everything. Had no idea that I needed to include that :smile:

No problem. Glad you got it up and running now :smile:

Where did you get your SHT-15 sensor from?

What is the advantage of the an SHT15 over a DHT22?

Its much more accurate and sensitive and a higher quality type sensor. The data sheets should have the specifics.

The DHT22 would probably be fine for most basic applications though.

To add to RWB’s comments, the big difference is that the SHT15 is an I2C device whereas the DHT22 is a 1-Wire device. In my experience with the DHT22, I find that if conditions (voltage, wire length) are not just right, the DHT22 will not read. In some cases if the 1-Wire timing is off, the DHT22 will stall until it is powered off then on again! With the SHT15, all those issues are removed because it is an I2C device. The downside of the SHT15 is that it is much more expensive than a DHT22.

So I have the spark core, and want to build an indoor temp and humidity sensor for my stepdad. He just had new hardwood floors put in their home and the installer was very strict about what the humidity levels should be in the home to maintain the floors. So what I’m wondering is, what would be the best way for him to monitor from his iphone or ipad?

Any thoughts?