ESP32 + ThingSpeak just send zero value.

Question

Armando Villegas 2023-2-9

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1909865-esp32-thingspeak-just-send-zero-value

评论： Christopher Stapels 2023-2-10

Hi everyone.

I'm trying to send the ADC value from a potentiometer to the ThingSpeak channel and I'm dealing with the problem that I send data to ThingSpeak and I just receive zero value in the channel even if I turn the potentiometer knob. If I run the program without the ThingSpeak configuration everything work well.

Could you help me, please?

I leave the source code below.

Thank you.

/*LIBRARIES*/
#include <Arduino.h>
#include "ThingSpeak.h"
#include "WiFi.h"
/*DEFINITIONS*/
#define ANALOGPIN      15
/*THINGSPEAK CONFIGURATION*/
const char* ssid = "xxxxxx";
const char* password = "xxxxxx";
unsigned long channelID = xxxxxxx;
const char* WriteAPIKey = "xxxxxx";
WiFiClient Client;
/*PROTOTYPES*/
void readPot (void);
/*--START FILE--*/
void setup()
{
    delay(2000);
    Serial.begin(115200);
    Serial.println("ESP32 ADC");
    
    /*WIFI CONNECTION*/
    WiFi.begin(ssid,password);
    while(WiFi.status() != WL_CONNECTED)
    {
        delay(500);
        Serial.print(".");
        }
    Serial.println("\nWifi connected");
    
    ThingSpeak.begin(Client);
    }
    
    void loop()
    {
        delay(2000);
        readPot();
        ThingSpeak.writeFields(channelID,WriteAPIKey);
        Serial.println("Send data.");
        Serial.println("---------------\n");
        delay(18000);
        }
    /*FUNCTION*/
    void readPot (void)
    {
        int potVal = analogRead(ANALOGPIN);
        while(isnan(potVal))
        {
            Serial.println("Read failed");
            delay(2000);
            potVal = analogRead(ANALOGPIN);
            }
        
        Serial.println("\nADC: ");
        Serial.println(potVal);
        
        ThingSpeak.setField(1,potVal);
        }
        /*-- END OF FILE --*/

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Armando Villegas 2023-2-10

I could find the problem.

https://arduino.stackexchange.com/questions/84888/analog-read-not-working-while-using-wifi

In that link explain why after connect to WiFi you lost the values form ADC.

Christopher Stapels 2023-2-10

I would consider returning the pot value from your function readPot and them calling setField in the same scope (in the main loop) as writefields. I'm not sure the variable information set with setField() in the function is transferred back to the main function.

I have multiple devices running for multiple years that read the ADC while wifi is connected with no problem.

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