9 Replies Latest reply on Jan 16, 2014 1:25 PM by AlexT_Intel

    Questions about Linux and OpenCV on galileo board




      I was wondering if it was possible to use OpenCV with Linux and the USB port.

      If it is possible, how would I go about doing it? Could I control it from the arduino software?



        • 1. Re: Questions about Linux and OpenCV on galileo board


          i have escalated this to the board support package team.

          in the meantime please ensure you are booting the large linux image from SD.

          the little image goes on the 8MB flash chip and is slimmed down to fit so wouldnt have OpenCv as far as i know.


          • 2. Re: Questions about Linux and OpenCV on galileo board

            I'm investigating the OpenCV support, at this time I guess there's no direct communication bridge between the "arduino like" environment and linux part. One idea could be to port the bridge library used by Arduino YUN.


            Another idea could be to implement in the Galileo Arduino libs the dbus protocol, as a dbus server is already compiled in the kernel. This way it will be easy to communicate with the linux side.


            What I'm currently doing, is to create a python web app using the CV module and poll it using the Arduino Ethernet driver, just connecting to localhost.


            Hope this helps, feel free to write me if you need more details at fiore.basile@gmail.com

            • 3. Re: Questions about Linux and OpenCV on galileo board

              hi Fiore,


              The arduino sketches on Galileo run as user space linux apps on the Quark SoC so you have access to linux right away without any Bridge API. Just make linux system(); calls from the sketch if you want.


              void loop() {

                // put your main code here, to run repeatedly:

                char cmd[50];

                sprintf(cmd, "uname -a > /dev/ttyGS0");





              On the CV/Python issue.

              There is python and openCV in the large SD image but there is an issue when importing CV into python.

              They both work standalone and the engineers here are looking at fixing the issue for the next release.


              • 4. Re: Questions about Linux and OpenCV on galileo board

                code below is easier:



                void setup() {

                  // put your setup code here, to run once:




                void loop() {

                  // some linux code that prints stuff to serial monitor

                  system("uname -a > /dev/ttyGS0");

                  system("ls / > /dev/ttyGS0");


                  // some arduino code that prints stuff to serial monitor

                  Serial.print("Its linux Jim, but not as we know it !!\n");



                • 5. Re: Questions about Linux and OpenCV on galileo board
                  Seth Hunter

                  I'm able to call a process like this from my home director:

                  system("node /home/root/nodeGalileo/1_geoPlaces.js > /dev/ttyGS0");


                  This outputs a value to the serial monitor. How can I parse this value and evaluate it to decide what to do next? In other words how do I read strings back into the arduino environment from processes on the linux side.



                  • 6. Re: Questions about Linux and OpenCV on galileo board



                    everything in linux is a file so below is one way, it may not be the most efficient but it works !

                    see some example sketches below....





                    This example shows how to use a system call to set current date & time with
                    UNIX 'date' command, then get the current time, redirect to a .txt file,
                    and read the contents of the text file back into the  sketch.

                    char buf[9];

                    void setup() {
                      system("date 010112002013"); //sets the date & time to 12:00 1st Jan 2013


                    void loop() {

                      system("date '+%H:%M:%S' > /home/root/time.txt");  //get current time in the format- hours:minutes:secs
                                                                         //and save in text file time.txt located in /home/root
                      FILE *fp;
                      fp = fopen("/home/root/time.txt", "r");
                      fgets(buf, 9, fp);
                      Serial.print("The current time is ");





                    This example shows how to read the temperature sensor on the Galileo's
                    onboard ADC, AD7298, using the iio (Industrial I/O) subsystem.

                    NOTE: This does not provide an accurate reading of the room tenmperature,
                    because the ADC is placed near the Quark SoC on the PCB, which gets quite warm.
                    As a result the ADC will always be a few degrees warmer than the actual room

                    char scale[4];
                    char raw[4];
                    char offset[4];

                    int raw_i;
                    int scale_i;
                    int offset_i;

                    int temp;

                    void setup() {


                    void loop() {
                      temp = getADCTemp();
                      Serial.print("Temperature is ");
                      Serial.println(" degrees celcius.");

                    int getADCTemp(){

                      FILE *fp_raw;
                      fp_raw = fopen("/sys/bus/iio/devices/iio:device0/in_temp0_raw", "r");     //read the values from scale, raw and offset files.
                      fgets(raw, 4, fp_raw);                                                    //we need all three values, because the formula for
                      fclose(fp_raw);                                                           //calulating the actual temperature in milli-degrees Celcius
                                                                                                //is: TEMP = (RAW + OFFSET) * SCALE
                      FILE *fp_scale;
                      fp_scale = fopen("/sys/bus/iio/devices/iio:device0/in_temp0_scale", "r");
                      fgets(scale, 4, fp_scale);
                      FILE *fp_offset;
                      fp_offset = fopen("/sys/bus/iio/devices/iio:device0/in_temp0_offset", "r");
                      fgets(offset, 4, fp_offset);
                      raw_i = atoi(raw);         //we have the values now, but they are in ASCII form-                                                      
                      scale_i = atoi(scale);     //we need them as integers so we can use them for calculations.
                      offset_i = atoi(offset);
                      int temp = (raw_i + offset_i) * scale_i;  //Calculate temperature in milli-degrees celcius
                      temp /= 1000;                         //divide by 1000 to convert to degrees celcius
                      return temp; 






                    This example uses Linux system calls to create a python script which writes
                    number 0-9 to a file, log.txt, one number per second. Then execute the
                    python script in the background, and regularly read the contents of the logfile
                    in the sketch while the python script is updating it.

                    char output[3];

                    void setup() {
                      system("echo '#!/usr/bin/python' > myScript.py");
                      system("echo 'import time' >> myScript.py");
                      system("echo 'for i in range(10):' >> myScript.py");
                      system("echo '    with open(\"log.txt\", \"w\") as fh:' >> myScript.py");
                      system("echo '        fh.write(\"{0}\".format(i))' >> myScript.py");
                      system("echo '    time.sleep(1)' >> myScript.py");
                      system("chmod a+x myScript.py");
                      system("./myScript.py &");    

                    void loop() {
                      FILE *fp;
                      fp = fopen("log.txt", "r");
                      fgets(output, 2, fp);

                    • 7. Re: Questions about Linux and OpenCV on galileo board
                      Seth Hunter

                      Thanks that's super helpful - I've been using this example and an article (with a slightly more elegant) implementation posted here: Enginursday: Exploring the Arduino/Intel Galileo - News - SparkFun Electronics


                      I suppose this is better than reading from the serial port because you have more control with a file system.

                      • 8. Re: Questions about Linux and OpenCV on galileo board

                        Thanks for this very helpful tutorial on how to access the Linux functionality from  arduino sketches.  Adding file access to arduino is a major advance.   Is there a single document somewhere that describes all the extentions that  Intel has made to the arduino language? Calls like system(), and all the file access commands like fopen(), fgets(), fclose().  What other goodies have you added?

                        • 9. Re: Questions about Linux and OpenCV on galileo board

                          I don't know of any such document, so I'll leave this to others to add comments, but in general your sketch is actually compiled into a normal 32-bit Linux binary program and run under Linux running on Galileo, so you have the full power of Linux :-) and can use pretty much all/most of standard Linux/POSIX functions, just keep in mind that's not a full-blown glibc, but an embedded uclibc. You can find the documentation either in the uclibc docs dir inside the tarball at uclibc.org, or just use Google and find some generic Linux/UNIX programming manual.