Trying to connect OLED to a WeMos D1 ESP8266

Other Hardware 3rd Party Boards
1

I’m trying to get a new board working for a project and I am having trouble getting the OLED to display anything. The board I am using is the “OTA WeMos D1 CH340 Arduino Compatible ESP8266 (12E)”.
I am very new at this, but am trying to learn as much as I can. What I have done so far. Installed CH340 USB driver, added Adafruit SSD1306 & Adafruit GFX to library. I have added the ESP8266 board package and selected the board “Lolin (WeMos)D1 R1”
I have connected the OLED to the board by itself for testing. Pictured below.

OLED
OLED818×768 99 KB

The OLED I’m using is a 128 X 32 I2C SSD1306 (5 volts)

I have the pins D14-SDA, D15-SCL, GRN-GRN, V5-VCC

I tested and I have 5 volts out of the board and I tested the OLED with a Arduino Uno and it work fine with it.

When I go to the Adafruit GFX library and upload the SSD1306 128x32 i2c sketch nothing appears on the display.

I then upload the I2Cdetect sketch as seen below and get the following errors. The errors go on father, this is just a portion that I copied.

Scanning...
Unknown error at address 0x01
Unknown error at address 0x02
Unknown error at address 0x03
Unknown error at address 0x04
Unknown error at address 0x05
Unknown error at address 0x06
Unknown error at address 0x07
Unknown error at address 0x08
Unknown error at address 0x09
Unknown error at address 0x0A
Unknown error at address 0x0B
Unknown error at address 0x0C
Unknown error at address 0x0D
Unknown error at address 0x0E
Unknown error at address 0x0F
Unknown error at address 0x10
Unknown error at address 0x11
Unknown error at address 0x12
Unknown error at address 0x13
Unknown error at address 0x14
Unknown error at address 0x15
Unknown error at address 0x16
Unknown error at address 0x17

// --------------------------------------
// i2c_scanner
//
// Version 1
//    This program (or code that looks like it)
//    can be found in many places.
//    For example on the Arduino.cc forum.
//    The original author is not know.
// Version 2, Juni 2012, Using Arduino 1.0.1
//     Adapted to be as simple as possible by Arduino.cc user Krodal
// Version 3, Feb 26  2013
//    V3 by louarnold
// Version 4, March 3, 2013, Using Arduino 1.0.3
//    by Arduino.cc user Krodal.
//    Changes by louarnold removed.
//    Scanning addresses changed from 0...127 to 1...119,
//    according to the i2c scanner by Nick Gammon
//    https://www.gammon.com.au/forum/?id=10896
// Version 5, March 28, 2013
//    As version 4, but address scans now to 127.
//    A sensor seems to use address 120.
// Version 6, November 27, 2015.
//    Added waiting for the Leonardo serial communication.
//
//
// This sketch tests the standard 7-bit addresses
// Devices with higher bit address might not be seen properly.
//

#include <Wire.h>


void setup() {
  Wire.begin();

  Serial.begin(9600);
  while (!Serial)
    ;  // Leonardo: wait for serial monitor
  Serial.println("\nI2C Scanner");
}


void loop() {
  byte error, address;
  int nDevices;

  Serial.println("Scanning...");

  nDevices = 0;
  for (address = 1; address < 127; address++) {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0) {
      Serial.print("I2C device found at address 0x");
      if (address < 16)
        Serial.print("0");
      Serial.print(address, HEX);
      Serial.println("  !");

      nDevices++;
    } else if (error == 4) {
      Serial.print("Unknown error at address 0x");
      if (address < 16)
        Serial.print("0");
      Serial.println(address, HEX);
    }
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");

  delay(5000);  // wait 5 seconds for next scan
}

Does anyone have any ideas what might be the issue?

2

I went to Adafruit.com and downloaded their Arduino I2c scanner. Code below.

// --------------------------------------
// i2c_scanner
//
// Modified from https://playground.arduino.cc/Main/I2cScanner/
// --------------------------------------

#include <Wire.h>

// Set I2C bus to use: Wire, Wire1, etc.
#define WIRE Wire

void setup() {
  WIRE.begin();

  Serial.begin(9600);
  while (!Serial)
    delay(10);
  Serial.println("\nI2C Scanner");
}


void loop() {
  byte error, address;
  int nDevices;

  Serial.println("Scanning...");

  nDevices = 0;
  for (address = 1; address < 127; address++) {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    WIRE.beginTransmission(address);
    error = WIRE.endTransmission();

    if (error == 0) {
      Serial.print("I2C device found at address 0x");
      if (address < 16)
        Serial.print("0");
      Serial.print(address, HEX);
      Serial.println("  !");

      nDevices++;
    } else if (error == 4) {
      Serial.print("Unknown error at address 0x");
      if (address < 16)
        Serial.print("0");
      Serial.println(address, HEX);
    }
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");

  delay(5000);  // wait 5 seconds for next scan
}

This was displayed on the serial monitor.

"Scanning...
I2C device found at address 0x3C !
done"

3

I was able to solve the problem. I opened the Adafruit SSD1306 library and uploaded the SSD1306 128 x32 i2c sketch but this time I changed the oled_reset to -1 and the display started working. So. problem solved.

4

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