analogRead returns 0 with wifi code added

Using Arduino Programming Questions
1

Using my ESP32 Wroom and a moisture sensor works flawlessly but as soon as I add the wifi module it returns 0's.

#include <WiFi.h>
#include <HTTPClient.h>
const char* ssid = "ssid";
const char* password = "1234";

const char* serverName = "http://maker.ifttt.com/trigger/plants/with/key/1234";
const int sensorPinMoist = 26;
int sensorPinMoistValue = 0;

# define relayPinSensor 33
# define relayPinPump 25
# define sensorPinMoist 26

int trigger = 300; // set the level

void setup()
{
  Serial.begin(115200);
  //wifi
  WiFi.begin(ssid, password);  // <-----------------------!! this line causes the sensorPinMoist to return 0
  // Serial.println("Connecting");
  // while(WiFi.status() != WL_CONNECTED) {
  //   delay(500);
  //   Serial.print(".");
  // }
  pinMode(relayPinSensor, OUTPUT); // turn on/off Sensor
  pinMode(relayPinPump, OUTPUT);    // turn on/off Pump  
}

void loop()
{
  //turn off Moisture Sensor (prevent corrosion)
  digitalWrite(relayPinSensor, LOW);
  Serial.println("");  
  delay(10000); 

  //turn on Moisture Sensor (prevent corrosion)
  digitalWrite(relayPinSensor, HIGH);
  //check moist value:  
  delay(3000);
  Serial.print("Moisture Sensor Value:");
  sensorPinMoistValue = analogRead(sensorPinMoist);
  Serial.println(sensorPinMoistValue);

  if (sensorPinMoistValue > trigger) 
  {
    // pump for ## seconds
    digitalWrite(relayPinPump, HIGH);
    delay(3000);
    digitalWrite(relayPinPump, LOW);
  }
  else
  {
    digitalWrite(relayPinPump, LOW);
    Serial.println("Pump standing by...");
    delay(3000); 
  }
}

what am i missing?

2

I don't know, but I'd guess the wifi uses pin 26 for something. Try using a different one for your sensor. Or look up which pins the wifi does actually need.

3

Nah, WiFi is integrated into the platform. AFAIK it doesn't occupy any of the GPIOs that are wired to external pins.

Don't know, but I'm missing a schematic of your project and details of components.

4

Which ESP32 do you have?
Bits and pieces of info. Typically, analog pins are on portB which is are pins 32 and up.
There are 2 A:D converts on the ESP32. Typically the 2nd A:D converter is disabled during WiFi. The 2nd AD converter uses portA or pins less then 32.

5

schematic with ESP32-WROOM-32 dev. board:

ESP32-30PIN-DEVBOARD copy

Sensor:

moist-sensor
moist-sensor608×503 113 KB

6

API Reference - ESP32 - — ESP-IDF Programming Guide latest documentation (espressif.com)

Analog to Digital Converter (ADC) - ESP32 - — ESP-IDF Programming Guide latest documentation (espressif.com)

ADC1:

  • 8 channels: GPIO32 - GPIO39

ADC2:

  • 10 channels: GPIO0, GPIO2, GPIO4, GPIO12 - GPIO15, GOIO25 - GPIO27
  • Since the ADC2 module is also used by the Wi-Fi, only one of them could get the preemption when using together, which means the adc2_get_raw() may get blocked until Wi-Fi stops, and vice versa.
7

Now that you are using the ADC2 converter. Now the documentation has this to say bout WiFi and ADC2

  • Since the ADC2 module is also used by the Wi-Fi, only one of them could get the preemption when using together, which means the adc2_get_raw() may get blocked until Wi-Fi stops, and vice versa.

Here is a list of ADC2 pins

Notice how pin 26 falls within that range of being on ADC2?

And what happens to ADC2 with WiFi use?

8

I've tried GPIO4, GPIO39. None of them worked

9

Post an image of your project. post a schematic.

10

You did not post that code.

11

See above. I replaced the GPIO numbers. Nothing spectacular.

12

Oh well I tried. I cannot see the image well enough to read the pin number, even after zooming in. Good luck.

13

Here you go

ESP32-30PIN-DEVBOARD
ESP32-30PIN-DEVBOARD2466×1341 319 KB

14

Try this connection:

  • Sensor VCC to 3.3V
  • Sensor GND to GND
  • Sensor A0 connected to GPIO 34, 35, 36 or 39.
15

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