Newbie - DHT11 and SH1106 OLED not working together

Projects Programming
1

So, I have this basic setup with a DHT11 and a SH1106 OLED display.
I can get the to work separately, but not together?!

/*********************************************************************
  This is an example for our Monochrome OLEDs based on SH110X drivers

  This example is for a 128x64 size display using I2C to communicate
  3 pins are required to interface (2 I2C and one reset)

  Adafruit invests time and resources providing this open source code,
  please support Adafruit and open-source hardware by purchasing
  products from Adafruit!

  Written by Limor Fried/Ladyada  for Adafruit Industries.
  BSD license, check license.txt for more information
  All text above, and the splash screen must be included in any redistribution

  i2c SH1106 modified by Rupert Hirst  12/09/21
*********************************************************************/
// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain

// REQUIRES the following Arduino libraries:
// - DHT Sensor Library: https://github.com/adafruit/DHT-sensor-library
// - Adafruit Unified Sensor Lib: https://github.com/adafruit/Adafruit_Sensor

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SH110X.h>
#include "DHT.h"

#define DHTPIN 2     // Digital pin connected to the DHT sensor
#define DHTTYPE DHT11   
#define i2c_Address 0x3c //initialize with the I2C addr 0x3C Typically eBay OLED's
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET -1   //   QT-PY / XIAO

DHT dht(DHTPIN, DHTTYPE);
Adafruit_SH1106G display = Adafruit_SH1106G(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
int cntr =0;


void setup(){
  Serial.begin(9600);
  delay(250); // wait for the OLED to power up
  display.begin(i2c_Address, true); // Address 0x3C default
  //display.setContrast (0); // dim display
  display.clearDisplay();
  display.display();
  myPrint("Starting...");
  delay(250);
  dht.begin();
}

void loop() {  
    // Wait a few seconds between measurements.
  delay(1000);
  cntr = cntr+1;
  float h=dht.readHumidity();
  float t=dht.readTemperature();
  /*float t=10;
  float h=20;
  h=h+cntr;
  t=t+cntr;*/
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t)) {
    //return;
    myPrint("Failed to read from DHT sensor!");
    }else{
      myPrint("Humidity: " + String(h) + "%" + "     Temperature: " + String(t) + "°C");
  }

}

void myPrint(String Text){
  Serial.println(Text);
  display.setTextSize(1);
  display.setTextColor(SH110X_WHITE);
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println(Text);
  display.display();
}

The output to the Serial Monitor works fine: I get the humidity and temperature - but the OLED keeps reading "Starting..."
If I do not read dht.readHumidity() and dht.readTemperature(): The OLED happily outputs the fixed values...

Any input to what is happening is appretiated!

2

You're probably running out of memory. The UNO has only 2kB of RAM and the SH1106 library is consuming about three quarters of it for the screen buffers and internal variable. And you're wasting the rest by using the String class and not using the F() macro for string literals.

3

Thanks!
That was it :smile: