1

I have been recently working on a website that takes input from the arduino ie- temperature and humidity. But there is a fatal problem that I've encountered, the serial monitor spews out some garbage with some actual readings. Is there a way to eliminate this?

 ╰─λ cat /dev/ttyACM0
T0°C
Humidity: 39.00%
00%
Temperature: 32.70°C
Humidity: 39.00%
Temperature: 32.70°C
Humidity: 39.00%
Temperature: 32.70°C
Humidity: 39.00%
00%
Temperature: 32.70°C
Humidity: 39.00%
Temperature: 32.70°C
Humidity: 39.00%
Temperature: 32.70°C
Humidity: 39.00%
idit9.00Tempure:70°Humi: 39
emperatu32.7
Huty: 0%
idit9.00Tempure:70°umidity.00%Tratu32.7
idit9.00Tempture.70�Humi: 39
empere: 0°Cmidi39.0
atur°C
Hum9.00

code-

#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h>

#define DHTPIN 4

#define DHTTYPE    DHT11
DHT_Unified dht(DHTPIN, DHTTYPE);

uint32_t delayMS;

void setup() {
  Serial.begin(9600);
  sensor_t sensor;
  dht.begin();
  delayMS = sensor.min_delay / 1000;
}

void loop() {
  delay(delayMS);
  sensors_event_t event;
  dht.temperature().getEvent(&event);
  if (isnan(event.temperature)) {
    Serial.println(F("Error reading temperature!"));
  }
  else {
    Serial.print(F("Temperature: "));
    Serial.print(event.temperature);
    Serial.println(F("°C"));
  }
  dht.humidity().getEvent(&event);
  if (isnan(event.relative_humidity)) {
    Serial.println(F("Error reading humidity!"));
  }
  else {
    Serial.print(F("Humidity: "));
    Serial.print(event.relative_humidity);
    Serial.println(F("%"));
  }
}

board - Arduino Uno (R3)

7
  • 1
    Welcome to Arduino:SE. Without seeing your code and hardware setup, we have no way to answer your question. Oct 3, 2022 at 5:48
  • @sempaiscuba thanks for correcting me. I have edited it now, let me know if there are some further corrections. Oct 3, 2022 at 5:57
  • I would print something unique in setup() that makes it evident in the output listing that it is only running once.
    – timemage
    Oct 3, 2022 at 6:04
  • What is the actual value of delayMS? The calculation looks fishy, since sensor is not initialized. The value should be around 2500ms.
    – PMF
    Oct 3, 2022 at 6:33
  • 1
    Do you have ModemManager installed on your system? Could you check that nobody else is messing with the serial port? Like this: sudo fuser -v /dev/ttyACM0. Oct 3, 2022 at 7:28

1 Answer 1

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As has been noted in the comments, you are trying to read the sensor at a rate that is too fast.

Try changing this line:

delayMS = sensor.min_delay / 1000;

to:

delayMS = sensor.min_delay = 1000;

or:

delayMS = sensor.min_delay = 3000;

This will read the sensor at a slower rate and should give you clean output.

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