ESP32 Forum

Posted: **Wed Dec 11, 2019 11:14 am**

Dear Forum,

after getting a little familiar with programming with Arduino, I'm at a point where I can't get any further. I am using an ESP32-POE-ISO. As part of the project, I want to synchronously read several sensors using the I2C protocol. Since several ESP32s are used, I need a method to synchronize them as accurately as possible. For this I use a local NTP server on a Raspberry (connected via Ethernet). Currently I get a jitter of max. +/-100 microseconds. I also tried a UDP broadcast, but the result is similar.
Do any of you have an idea for a method to improve this value (->smaller jitter)? Maybee causing an interrupt via UDP?

Thanks in advance,

Kainer

Code: [Select all] [Expand/Collapse]

#include <WiFi.h>
#include <ETH.h>
#include "time.h"
 
TaskHandle_t Task1;
time_t new_t, old_t;
void codeForTask1(void * parameter)
{
  const long  gmtOffset_sec = 3600;
  const int   daylightOffset_sec = 3600;
//  time_t new_tl, old_tl;   
  for(;;){
    delay(1000); 
    configTime(gmtOffset_sec, daylightOffset_sec, "192.168.1.2");                          
  }
}
void setup()
{
    Serial.begin(115200);
    Serial.println("Start .......");
    pinMode(5, OUTPUT);      // set the LED pin mode
    ETH.begin();
    ETH.config(IPAddress(192, 168, 1, 66),IPAddress(192, 168, 1, 255),IPAddress(255, 255, 255, 0));
    delay(100);
    xTaskCreatePinnedToCore(codeForTask1,"Task_1",10000,NULL,1,&Task1,0); 
    old_t=0;
}
 
void loop(){ 
    time(&new_t); 
    if(difftime(new_t,old_t)!=0) 
      {
        pinMode(5, INPUT);      // set the LED pin mode 
        delayMicroseconds(100);
        old_t=new_t;  
      }
  pinMode(5, OUTPUT); 
}
 
 

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