Trouble using popen() on a pi3

The Archive Raspberry Pi
1

I have a simple program to get data from a python script and publish it. when I call a simple python script (print(‘Hello’)) everything works fine. But the script I want to call has a delay of 10 seconds (scanning bluetooth LE sensors) before it returns a string. If I run the same code on the Pi itself it waits the 10 seconds and then prints the data. But the Particle code doesn’t wait and returns no data.

2

Having some code to look at would definitely help :wink:

1 Like
3

Not much to it:

#include <stdio.h>

char c[20];
FILE *pyin;

void setup() {
    Serial.begin(9600);
}

void loop() {
    if (Time.second() == 0){
        getTemp();
        Particle.publish("outside",c,60,PRIVATE);
        delay(1000);
    }
}

void getTemp(){
    pyin = popen("/root/python/particle_test.py","r");
	fscanf(pyin,"%[^\n]",c);
	Serial.printlnf("Data from Python: %s",c);
	pclose(pyin);
}

Thanks peekay123

4

The fix proved to be simple, added a ‘delay(x)’ between the popen a fscanf lines.