# Intermittent ArrayIndexOutOfBoundsException reading thermopile over serial

**URL:** <https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361>\
**Category:** Electronics (Arduino, etc.)\
**Created:** [September 22, 2021, 2:55am UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361 "2021-09-22T02:55:03Z")\
**Posts on this page:** 10\
**Page:** 1

<div class="post-metadata">

**Author:** ![The\_Wolf\_of\_Walmart](https://avatars.discourse-cdn.com/v4/letter/t/a88e57/32.png) [@The\_Wolf\_of\_Walmart](https://discourse.processing.org/u/The_Wolf_of_Walmart)\
**Post date:** [September 22, 2021, 2:55am UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/1 "2021-09-22T02:55:03Z")

</div>

Hello all. I’m trying to integrate the heatcam example sketches([Github](https://github.com/sparkfun/Qwiic_GRIDEye)) related to the [Grid Eye Qwiik breakout](https://learn.sparkfun.com/tutorials/qwiic-grid-eye-infrared-array-amg88xx-hookup-guide) from Sparkfun, into a bigger project, but am not able to it running reliably on it’s own. When it works, it works just fine and I am seeing the results from both the Arduino and Processing sides are operating as expected. Here are the example sketches:

> **Arduino**
>
> ```auto
> /*
> Visualizing the Panasonic Grid-EYE Sensor Data using Processing
> By: Nick Poole
> SparkFun Electronics
> Date: January 12th, 2018
>   
> MIT License: Permission is hereby granted, free of charge, to any person obtaining a copy of this 
> software and associated documentation files (the "Software"), to deal in the Software without 
> restriction, including without limitation the rights to use, copy, modify, merge, publish, 
> distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the 
> Software is furnished to do so, subject to the following conditions:
> 
> The above copyright notice and this permission notice shall be included in all copies or 
> substantial portions of the Software.
> 
> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING 
> BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
> NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
> DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
> OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
>   
> Feel like supporting our work? Buy a board from SparkFun!
> https://www.sparkfun.com/products/14568
>   
> This example is intended as a companion sketch to the Processing sketch found in the same folder.
> Once this code is running on your hardware, open the accompanying Processing sketch and run it 
> as well. The Processing sketch will receive the comma separated values generated by this code and
> use them to generate a thermal image. If you don't have Processing, you can download it here:
> https://processing.org/
>   
> Hardware Connections:
> Attach the Qwiic Shield to your Arduino/Photon/ESP32 or other
> Plug the sensor onto the shield
> */
> 
> #include <Wire.h>
> #include <SparkFun_GridEYE_Arduino_Library.h>
> 
> GridEYE grideye;
> 
> void setup() {
> 
> // Start your preferred I2C object 
> Wire.begin();
> // Library assumes "Wire" for I2C but you can pass something else with begin() if you like
> grideye.begin();
> // Pour a bowl of serial
> Serial.begin(115200);
> 
> }
> 
> void loop() {
> 
> // Print the temperature value of each pixel in floating point degrees Celsius
> // separated by commas 
> for(unsigned char i = 0; i < 64; i++){
> Serial.print(grideye.getPixelTemperature(i));
> Serial.print(",");
> } 
> 
> // End each frame with a linefeed
> Serial.println();
> 
> // Give Processing time to chew
> delay(100);
> 
> }
> 
> ```

> **Processing**
>
> ```auto
> /*
> Visualizing the Panasonic Grid-EYE Sensor Data using Processing
> By: Nick Poole
> SparkFun Electronics
> Date: January 12th, 2018
>   
> MIT License: Permission is hereby granted, free of charge, to any person obtaining a copy of this 
> software and associated documentation files (the "Software"), to deal in the Software without 
> restriction, including without limitation the rights to use, copy, modify, merge, publish, 
> distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the 
> Software is furnished to do so, subject to the following conditions:
> 
> The above copyright notice and this permission notice shall be included in all copies or 
> substantial portions of the Software.
> 
> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING 
> BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
> NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
> DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
> OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
>   
> Feel like supporting our work? Buy a board from SparkFun!
> https://www.sparkfun.com/products/14568
>   
> This example is intended as a companion sketch to the Arduino sketch found in the same folder.
> Once the accompanying code is running on your hardware, run this Processing sketch. 
> This Processing sketch will receive the comma separated values generated by the Arduino code and
> use them to generate a thermal image.
>   
> Hardware Connections:
> Attach the Qwiic Shield to your Arduino/Photon/ESP32 or other
> Plug the sensor onto the shield
> */
> 
> import processing.serial.*;
> 
> String myString = null;
> Serial myPort; // The serial port
> 
> float[] temps = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
> 
> // The statements in the setup() function 
> // execute once when the program begins
> void setup() {
> size(400, 400); // Size must be the first statement
> noStroke();
> frameRate(30);
>   
> // Print a list of connected serial devices in the console
> printArray(Serial.list());
> // Depending on where your GridEYE falls on this list, you
> // may need to change Serial.list()[0] to a different number
> myPort = new Serial(this, Serial.list()[2], 115200);
> myPort.clear();
> // Throw out the first chunk in case we caught it in the 
> // middle of a frame
> myString = myPort.readStringUntil(13);
> myString = null;
> // change to HSB color mode, this will make it easier to color
> // code the temperature data
> colorMode(HSB, 360, 100, 100);
> }
> 
> // The statements in draw() are executed until the 
> // program is stopped. Each statement is executed in 
> // sequence and after the last line is read, the first 
> // line is executed again.
> void draw() { 
>   
> // When there is a sizeable amount of data on the serial port
> // read everything up to the first linefeed
> if(myPort.available() > 64){
> //delay(100);
> myString = myPort.readStringUntil(13);
>   
> // generate an array of strings that contains each of the comma
> // separated values
> if (myString !=null) // had to enclose the following in this if statement to solve null pointer exception errors
> {
> String splitString[] = splitTokens(myString, ",");
> printArray(splitString);
> // for each of the 64 values, map the temperatures between 20C and 40C
> // to the blue through red portion of the color space
> for(int q = 0; q < 64; q++){
>    
> temps[q] = map(float(splitString[q]), 35, 39, 100, 360);
>     
> }
> }
> }
>   
>   
> // Prepare variables needed to draw our heatmap
> int x = 0;
> int y = 0;
> int i = 0;
> background(0); // Clear the screen with a black background
>   
>   
> // each GridEYE pixel will be represented by a 50px square: 
> // because 50 x 8 = 400, we draw squares until our y location
> // is 400
> while(y < 400){
>   
>     
> // for each increment in the y direction, draw 8 boxes in the 
> // x direction, creating a 64 pixel matrix
> while(x < 400){
> // before drawing each pixel, set our paintcan color to the 
> // appropriate mapped color value
> fill(temps[i], 100, 100);
> rect(x,y,50,50);
> x = x + 50;
> i++;
> }
>   
> y = y + 50;
> x = 0;
> }
>   
> // Add a gaussian blur to the canvas in order to create a rough
> // visual interpolation between pixels.
> filter(BLUR,10);
> }
> 
> ```

However, I have to start the Processing sketch many times before it _does_ behave- I have probably a 30% success rate every time. When it does not work, I get the following error (Not always 23):

```auto
map(NaN, 35, 39, 100, 360) called, which returns NaN (not a number)
ArrayIndexOutOfBoundsException: 23

```

I put a `printArray` right after the ` String splitString[] = splitTokens(myString, ",");`  
And this is what is in the console when it throws the error:

```auto
[0] "COM1"
[1] "COM3"
[2] "COM4"
[0] "16.25"
[1] "16.75"
[2] "16.25"
[3] "16.00"
[4] ".00"
[5] "17.50"
[6] "17.50"
[7] "17.25"
[8] "17.50"
[9] "18.00"
[10] "18.50"
[11] "18.50"
[12] "18.75"
[13] "19.50"
[14] "18.00"
[15] "18.00"
[16] "17.25"
[17] "18.00"
[18] "18.00"
[19] "18.00"
[20] "19.00"
[21] "19.00"
[22] "
"
map(NaN, 35, 39, 100, 360) called, which returns NaN (not a number)
ArrayIndexOutOfBoundsException: 23

```

I’ve tried solutions from the issues section of the github as well as some from other posts both here and in the Arduino forum but I just can’t figure out what is wrong.

---

<div class="post-metadata">

**Author:** ![noahbuddy](https://avatars.discourse-cdn.com/v4/letter/n/73ab20/32.png) [@noahbuddy](https://discourse.processing.org/u/noahbuddy)\
**Post date:** [September 22, 2021, 4:38am UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/2 "2021-09-22T04:38:19Z")

</div>

One possibility is to change the loop on the Processing side:

```auto
for(int q = 0; q < (splitString.length-1); q++){
    temps[q] = map(float(splitString[q]), 35, 39, 100, 360);
}

```

A more robust solution would be to check against `Float.NaN` after a float conversion.  
Also, I use length-1 because the end-line character is included in the array (index 22 in your example).  
While it will convert to a valid number, it will not be an accurate temperature.

---

<div class="post-metadata">

**Author:** ![jafal](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/jafal/32/19112_2.png) [@jafal](https://discourse.processing.org/u/jafal)\
**Post date:** [September 22, 2021, 6:03am UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/3 "2021-09-22T06:03:02Z")

</div>

Hi

Maybe this helps

> [@HeatCam examples .... Please help!](https://discourse.processing.org/t/heatcam-examples-please-help/29390):
>
> Hi! I’m the real beginner in this field frowning I tried to follow various examples with my Sparkfun parts. And I’m trying to do the example with processing Heatcam. ( Example 4 - Processing Heat Cam) I do everything what they said (also checked the COM number) but it kept popping the the message of (NullPointerException). /\* Visualizing the Panasonic Grid-EYE Sensor Data using Processing By: Nick Poole SparkFun Electronics Date: January 12th, 2018 MIT License: Permission is …

---

<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:** [September 22, 2021, 1:53pm UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/4 "2021-09-22T13:53:51Z")

</div>

Hello @The_Wolf_of_Walmart,

Take a look here:  
[https://discourse.processing.org/t/heatcam-examples-please-help/29390/4](https://discourse.processing.org/t/heatcam-examples-please-help/29390/4)

I had the same reaction (below) to this as I did in my post above!

> [@HeatCam examples .... Please help!](https://discourse.processing.org/t/heatcam-examples-please-help/29390/4):
>
> That is a lot of zeroes!
> 
> ```auto
> //float[] temps = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
> float[] temps = new float [64];
> printArray(temps);
> 
> ```
> 
> `:)`

Have fun!

`:)`

---

<div class="post-metadata">

**Author:** ![The\_Wolf\_of\_Walmart](https://avatars.discourse-cdn.com/v4/letter/t/a88e57/32.png) [@The\_Wolf\_of\_Walmart](https://discourse.processing.org/u/The_Wolf_of_Walmart)\
**Post date:** [September 22, 2021, 4:24pm UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/5 "2021-09-22T16:24:26Z")

</div>

> [@noahbuddy](#):
>
> One possibility is to change the loop on the Processing side:
> 
> ```auto
> for(int q = 0; q < (splitString.length-1); q++){
> temps[q] = map(float(splitString[q]), 35, 39, 100, 360);
> }
> 
> ```

I will give that a try this afternoon and see how it goes- fingers crossed.

> [@noahbuddy](#):
>
> A more robust solution would be to check against `Float.NaN` after a float conversion.

Could you elaborate a little more on what that might look like?

@jafal & @glv : thank you for your replies. I spent a good bit of time implementing the suggestions from that post but didn’t have any success. Perhaps I can give it another try and post the code in case I didn’t do it correctly.

---

<div class="post-metadata">

**Author:** ![The\_Wolf\_of\_Walmart](https://avatars.discourse-cdn.com/v4/letter/t/a88e57/32.png) [@The\_Wolf\_of\_Walmart](https://discourse.processing.org/u/The_Wolf_of_Walmart)\
**Post date:** [September 22, 2021, 4:30pm UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/6 "2021-09-22T16:30:14Z")

</div>

@glv Actually, it looks like I still have that code open on my laptop. Here is what I had on Processing side when I tried your suggestion:

> **Processing**
>
> ```auto
> 
> import processing.serial.*;
> 
> String myString = null;
> Serial myPort; // The serial port
> 
> //See if you can isntantiate the temp array with [64] instead of 64x 0's
> float[] temps = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
> int comPort = 1; //Change active comport here
> 
> // The statements in the setup() function 
> // execute once when the program begins
> void setup() {
> 
> size(400, 400); // Size must be the first statement
> noStroke();
> frameRate(30);
> 
> // Print a list of connected serial devices in the console
> printArray(Serial.list());
> 
> // Depending on where your GridEYE falls on this list, you
> // may need to change Serial.list()[0] to a different number
> myPort = new Serial(this, Serial.list()[comPort], 115200);
> myPort.clear();
> // Throw out the first chunk in case we caught it in the 
> // middle of a frame
> myString = myPort.readStringUntil(13);
> myString = null;
> 
> // change to HSB color mode, this will make it easier to color
> // code the temperature data
> colorMode(HSB, 360, 100, 100);
> }
> 
> // The statements in draw() are executed until the 
> // program is stopped. Each statement is executed in 
> // sequence and after the last line is read, the first 
> // line is executed again.
> void draw() { 
> 
> // When there is a sizeable amount of data on the serial port
> // read everything up to the first linefeed
> if (myPort.available() > 64) {
> myString = myPort.readStringUntil(13); //13 = carriage return or \r
> 
> if (myString !=null) // had to enclose the following in this if statement to solve null pointer exception errors
> {
> float frameMin; //lowest temp in frame
> float frameMax; //highest temp in frame
> float frameAvg; //avg temp of frame
> float avgDelta; //average of change of each pixel from it's previous reading
> float sumDelta; //total amount of pixel change since last frame
> int hottestPixel; //XY of hottest pixel in frame
> 
> // generate an array of strings that contains each of the comma
> // separated values
> 
> trim(myString);
> String splitString[] = splitTokens(myString, ",");
> printArray(splitString);
> if (splitString.length == 65)
> {
> 
> // for each of the 64 values, map the temperatures between 20C and 40C
> // to the blue through red portion of the color space
> for (int q = 0; q < 64; q++) {
> 
> // orig temps[q] = map(float(splitString[q]), 20, 40, 240, 360);
> 
> // This controls the contrast sesitivity/temp resolution, arguments 2 & 3 should probably be average min/max
> // of that observed during given stage of sleep
> temps[q] = map(float(splitString[q]), 35, 39, 100, 360); //temps variable = temp scaled to color range
> }
> }
> }
> 
> // Prepare variables needed to draw our heatmap
> int x = 0;
> int y = 0;
> int i = 0;
> background(0); // Clear the screen with a black background
> 
> // each GridEYE pixel will be represented by a 50px square: 
> // because 50 x 8 = 400, we draw squares until our y location
> // is 400
> while (y < 400) {
> 
> // for each increment in the y direction, draw 8 boxes in the 
> // x direction, creating a 64 pixel matrix
> while (x < 400) {
> // before drawing each pixel, set our paintcan color to the 
> // appropriate mapped color value
> fill(temps[i], 100, 100);
> rect(x, y, 50, 50);
> x = x + 50;
> i++;
> }
> 
> y = y + 50;
> x = 0;
> }
> 
> // Add a gaussian blur to the canvas in order to create a rough
> // visual interpolation between pixels.
> filter(BLUR, 10);
> } 
> }
> 
> ```

---

<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:** [September 22, 2021, 10:33pm UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/7 "2021-09-22T22:33:12Z")

</div>

Hello @The_Wolf_of_Walmart ,

Seems to work with this Arduino test code:

> **Arduino Code**
>
> ```auto
> int count;
> 
> void setup() 
> {
> Serial.begin(115200);
> delay(1000);
> }
> 
> void loop() 
> {
> Serial.print(count++); // First element is a counter! Useful when debugging code.
> Serial.print(",");
> for(unsigned char i = 0; i < 63; i++){
> Serial.print((i+1)*1.01);
> Serial.print(",");
> } 
> Serial.println();
> delay(500);
> }
> 
> ```

I got this from the numbers I was sending:

![image](https://canada1.discourse-cdn.com/flex036/uploads/processingfoundation1/original/2X/b/b806662e22bda5cab38e688f63a4774acbc7b9ee.png)

My use of trim in topic provided was incorrect!  
I spotted that right away! Live and learn…  
It did not matter in this case since we did not use last element of array.  
Will go back and fix it in original post.

This is correct:

```auto
myString = trim(myString);
String splitString[] = splitTokens(myString, ",");
printArray(splitString);
if (splitString.length == 64)

```

Another topic that may be of interest:

> [@Problem with the use of several sensors, Arduino / Processing](https://discourse.processing.org/t/problem-with-the-use-of-several-sensors-arduino-processing/18118/5):
>
> Hello, Some code I wrote to explore Arduino transmitting data to Processing. It runs fine at a BAUD rate of 1000000. slight_smile I use an Arduino MEGA 2560 R3. 
> 
> > **Arduino Code**
> >
> > // Serial Incoming Test (Arduino Tx) // v1.0.0 // GLV 2020-02-29 long count; void setup() { //Serial.begin(9600); Serial.begin(1000000); delay(1000); Serial.print('\n'); //same as Serial.println() Serial.print("incoming"); Serial.print('\n'); //same as Serial.println() } void loop() …

You may have been experiencing some “garbage” in the buffers if you were just stopping and running Processing.  
There are better ways to do things like handshaking between devices… when you are ready.

`:)`

---

<div class="post-metadata">

**Author:** ![noahbuddy](https://avatars.discourse-cdn.com/v4/letter/n/73ab20/32.png) [@noahbuddy](https://discourse.processing.org/u/noahbuddy)\
**Post date:** [September 23, 2021, 4:27am UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/8 "2021-09-23T04:27:41Z")

</div>

> [@The\_Wolf\_of\_Walmart](#):
>
> Could you elaborate a little more on what that might look like?

You can do something like:

```auto
float value = float(splitString[q]);
if (Float.NaN != value)
{
  temps[q] = map(value, 35, 39, 100, 360);
}

```

---

<div class="post-metadata">

**Author:** ![RichardDL](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@RichardDL](https://discourse.processing.org/u/RichardDL)\
**Post date:** [September 23, 2021, 9:19pm UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/9 "2021-09-23T21:19:17Z")

</div>

Hi @The_Wolf_of_Walmart, Re getting things to work reliably. On a couple of projects I’ve found that the Mega does not like receiving serial when it’s not ready. See this [topic](https://discourse.processing.org/t/program-slower-when-i-send-data-to-arduino/19815/6).

---

<div class="post-metadata">

**Author:** ![The\_Wolf\_of\_Walmart](https://avatars.discourse-cdn.com/v4/letter/t/a88e57/32.png) [@The\_Wolf\_of\_Walmart](https://discourse.processing.org/u/The_Wolf_of_Walmart)\
**Post date:** [September 26, 2021, 5:09pm UTC](https://discourse.processing.org/t/intermittent-arrayindexoutofboundsexception-reading-thermopile-over-serial/32361/10 "2021-09-26T17:09:10Z")

</div>

I made your suggested changes to the code again and it’s working great! 🙂 Thank you very much. Thank you for the link as well- my next step is to integrate accelerometer and RTC, so I’m sure I will be referring to it.