# Weird DHT11 reading

**URL:** <https://discourse.processing.org/t/weird-dht11-reading/42869>\
**Category:** Electronics (Arduino, etc.)\
**Created:** [October 1, 2023, 2:59pm UTC](https://discourse.processing.org/t/weird-dht11-reading/42869 "2023-10-01T14:59:41Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![bkeith](https://avatars.discourse-cdn.com/v4/letter/b/57b2e6/32.png) [@bkeith](https://discourse.processing.org/u/bkeith)\
**Post date:** [October 1, 2023, 2:59pm UTC](https://discourse.processing.org/t/weird-dht11-reading/42869/1 "2023-10-01T14:59:41Z")

</div>

I’m trying read values from a DHT11 sensor on my arduino uno. I have a very simple arduino sketch that writes just humidity, that’s the only value I want. I wrote a very simple processing sketch (see below) that reads and displays this value, it works but I get weird results. When I run the sketch it displays the value every 1 second, but right before displaying the next reading, it very quickly cycles through numbers 0-255 then displays the value. What is causing this? any ideas how to fix it? Thanks!

```auto
import processing.serial.*;

Serial myPort; 

int humidity;

void setup() {
  size(200, 200);
  
  myPort = new Serial(this, "COM3", 9600);
}

void draw() {
  if (myPort.available() > 0) {
    humidity = myPort.read();
  }
  background (0, 0, 255);
  if (humidity >= 0) {
    fill(255);
    textSize(20);
    text(humidity, 10, 10);
  }
}

```

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<div class="post-metadata">

**Author:** ![glv](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/glv/32/18785_2.png) [@glv](https://discourse.processing.org/u/glv)\
**Post date:** [October 1, 2023, 4:02pm UTC](https://discourse.processing.org/t/weird-dht11-reading/42869/2 "2023-10-01T16:02:12Z")

</div>

Hello @bkeith ,

What are you seeing on the Arduino monitor without Processing?

You may have some garbage in your buffers… try it with _while()_ and report back.  
I experience this when starting Processing when receiving from Arduino in some cases and have various strategies to address this.

I am assuming you are sending one byte of data (value 0 to 255) every 1000ms from Arduino.

`while (mySerial.available() > 0)` will receive multiple bytes of data per frame and flush out the buffers.  
In your code you will use the last byte that was read.

`if (mySerial.available() > 0)` will only receive one bye of data per frame; the data will be stuck in the buffer until it is _read()_ the next frame and eventually cleared.  
You may be seeing some garbage in your buffers using the _if()_ statement until you clear it out… one frame per byte.

You can monitor the buffer with a simple statement:

```auto
println(mySerial.available());

```

Reference:

> **[available() / Libraries](https://processing.org/reference/libraries/serial/Serial_available_.html)**
>
> Returns the number of bytes available.

`:)`