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SHT15 Humidity and Temperature Breakout Board



anyone tried this code to SHT15?

i modified it a bit to make it work, but it shows exception at start about the soft reset

anyone knows what is wrong? i power it at 3v (tried 5v too) and the DATA and SCK on IO19, IO18.

P.S. General question: its annoying that wires are not fixed on their position(board, sensor etc) and when i try to wire something , something else goes out. How do you make the wiring guys? Cause im new to these stuff.


We use breadboards and jumper wires (male/male, female/female, male/female)


yea i need a breadboard i guess thx. i have the others

about the sensor…i don’t even know if it’s working. If we assume that the code has problem , how can i check if sensor works and gets power?


Have you placed a pullup to 3.3v on the data line ?

They don’t work unless they have this in place.

Cheers Ian


what do you mean? its the breakout board from sparkfun
so the clock pin has a 10K pull-down resistor, and data pin has a 10K pull-up

I did like this:

VCC pin to 3.3V(tried 5v too)
GND pin to GND
Data pin to IO19
SCK pin to IO18


ok now it worked w/o chaning anything weird :smiley:

but i get the following values

RAW Temperature 12-Bit: 0
RAW Humidity 8-Bit: 0
RAW Temperature 14-Bit: 0
RAW Humidity 12-Bit: 0
Temperature F: -39.5
Humidity in percent: -2.6937998913154004
DewPoint in F: nan
Temperature F: -39.5
Humidity in percent: -2.6937998913154004
DewPoint in F: nan

doesn’t change values, always same loop

any thoughts?


Ok the resistor is on the sparkfun BOB

The values you’re getting are Max’ed out negative… This happens when its reading 0xFF ( all bits high ) which means there is no communication…

I’ve noticed that on the breakout board they have the SCK line with a pulldown resistor!! You need to check if you have a clock signal… I don’t know whether the device driver on the FEZ is driving the pin high the serial transfers.

This driver is for a different device… Are the registers the same?

Cheers Ian


thx for reply

well i use these according the sht15 documentation

            MeasureTemperature = 0x03,
            MeasureRelativeHumidity = 0x05,
            ReadStatusRegister = 0x07,
            WriteStatusRegister = 0x06,
            SoftReset = 0x1E,


trying to debug it, it never enters on the part of code that i have the debug msg.
so it doesnt read anything from the registers i guess

private byte ReadByte(bool ACK)
            // Storage for read byte
            byte readTemp = 0;

            for (byte bit = 0; bit < 8; bit++)
                // Shift bits in buffer to right
                readTemp = (byte)(readTemp << 1);

                // Raise Clock
                IOProvider.Clock = true;

                // Check Data for bit
                if (IOProvider.Data == true)
                    readTemp |= 0x01;
                    // never enters here
                    Debug.Print("readTempRB = " + readTemp.ToString());
                // Lower Clock
                IOProvider.Clock = false;


            // Ack
            IOProvider.Data = !ACK;
            IOProvider.Clock = true;
            IOProvider.Clock = false;
            IOProvider.Data = true;

            // Return Read byte
            return readTemp;


Edit: It worked finally :slight_smile:


Ok !!! don’t leave me hanging… what did you find that sorted it out…

Cheers Ian


yea sorry i forgot to write it. ^^
Thanks for your replies, your post helped me when you said max values mean no communication.
So i played with the volt and pins and finally pins should be opposite from what the driver(from fezzer) says.

it said on the comments first clock pin then data pin and 3.3v
but eventually its first data pin and then clock pin and 5v for SHT15.

now i have another question for you. :-[
I also bought this

I wanted a light detector sensor, i bought it in order to check the light on the room so i can check if its night or day. But finally i don’t know if i bought the correct one. :confused:
(i bought this because the EU distributor of GHI ( didnt have the GHI Light Sensor unfortunatelly)

any thoughts?