ESP8266 not running oled properly

So, I am making a bike speedometer, and it is working fine on my Arduino development board (Arduino UNO). Since it all was working fine, I uploaded the program to an esp12e chip (as in the raw chip) and tested it. My problem is that the OLED display remains black. Can anyone tell me what I am doing wrong? I have attached a schematic of my wiring and my code.

code:

#include <ESP8266WiFi.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

const int freq = 1000; //Display refresh frequency
const int sensPin = 14; //Sensor pin #
const double pi = 3.14159265359; //Declaration of pi as a constant number
const int mags = 2; //Number of magnets on the bike ***CHANGE***
const double R = 0.34; //Radius of the bike whell ***CHANGE***

double u = 0; //Velocity
double T = 0; //Interval between two reads
long double prevTime = 0; //Previous time

int trig = 0;
int dist1 = 0;

void setup() {
  WiFi.mode( WIFI_OFF );
  WiFi.forceSleepBegin();
  delay(1);
  pinMode(sensPin, INPUT);
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    for (;;);
  }
  digitalWrite(LED_BUILTIN, HIGH);
  display.clearDisplay();
  display.setTextSize(1.5);
  display.setTextColor(WHITE);
  display.setCursor(0, 10);
  display.display();
}

void loop() {
  if (digitalRead(sensPin)) {
    T = mags * (millis() - prevTime);
    prevTime = millis();
    u = ((2 * pi * R) / T) * 3600;
    while (digitalRead(sensPin)) disp(u);
  }
  if (digitalRead(sensPin) == HIGH && trig == 2) {
    dist1 += 2 * R * pi;
    trig = 0;
  } else if (digitalRead(sensPin) == HIGH) {
    trig ++;
  }
  if (millis() - prevTime > 4000 / mags) u = 0;
  disp(u);
}

void disp(double U) {
  display.clearDisplay();
  display.setCursor(0, 10);
  display.print("Speed: ");
  display.print(U);
  display.println(" km/h");
  display.print("Distance: ");
  display.print(dist1);
  display.println(" m");
  display.setCursor(0, 10);
  display.display();
}

Schematic
Note on the schematic: In the circuit diagram, VCC is shown to be connected to 5v. This is an error on my part. In reality, it is connected to 3.3v . Sorry for any confusion caused by this.

Does anyone know why this is happening?

can you give details of the OLED display? e.g. will it work with a 3.3V power supply?

Yes. The OLED runs fine on a 3.3v power supply, and has built-in pullup resistors. It is a 0.96" blue display with the SSD1306 driver. hope this helps!

Powering a bare ESP-12 with 5volt doesn't seem right.
Leo..

Sorry, that was a typo on my part in the circuit diagram. The whole chip setup is powered by 3.3v. I will edit that.

Just to confirm that this part is reached within the code.

digitalWrite(LED_BUILTIN, HIGH);

could you first set the GPIO to OUTPUT, and then light it up by setting the pin 'LOW" since it is 'active low'

pinMode(LED_BUILTIN, OUTPUT);
digitalWrite(LED_BUILTIN, LOW);

Normally with a 12e (or f) it is on GPIO 2 which is the same as the default setting in the IDE for it if using generic 8266 module.

I will try this and get back to you.

So presumably you have some way to view serial monitor with the esp?

Have you tried running the i2c scanner sketch to check if the oled is visible on the bus?

that library didnt work for me too. I did a search and found another. try anothers

connected a 0.96" blue display with the SSD1306 driver to a NodeMCU_V1_ESP12E
and run File>Examples>Adafruit_SSD1306>ssd1306_128x64_i2c
changed I2C address to 0x3C and example runs OK

1 Like

I would really like to know what happens (in the serial monitor) if you enter a bad I2C address.

updated example to do some more prints

void setup() {
  Serial.begin(115200);
  while(!Serial);
  delay(1000);
  Serial.println("\nSSD1306 LCD test");
  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }
 Serial.println("\nSSD1306 LCD found OK");

if the I2C address is incorrect (e.g.0x3D) the serial monitor displays

SSD1306 LCD test

SSD1306 LCD found OK

as though all is OK and LCD found (nothing appears on the LCD)
i.e. I would have expected it to display and go into endless loop

Serial.println(F("SSD1306 allocation failed"));

Thank you very much

I was hoping for a hungry watchdog reset...
That would have explained something from https://forum.arduino.cc/t/problem-with-programmed-via-arduino-ideesp8266-rst-cause-4-boot-mode-3-7-im-driving-crazy-already/1067757

Well the endless loop will only last for 2.5 secs and then the wdt resets the ESP.

So sorry to not have responded to this, life has been busy and I honestly just forgot. I tested the same circuit with the Adafruit official example (edited I2C address) and it worked perfectly. Then I tried to run the code below (I edited out unnecessary stuff to help me see why it wasn't working, but the full code that I programmed the board with is below)

#include <ESP8266WiFi.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

const int freq = 1000; //Display refresh frequency
const int sensPin = 14; //Sensor pin #
const double pi = 3.14159265359; //Declaration of pi as a constant number
const int mags = 2; //Number of magnets on the bike ***CHANGE***
const double R = 0.34; //Radius of the bike whell ***CHANGE***

double u = 0; //Velocity
double T = 0; //Interval between two reads
long double prevTime = 0; //Previous time

int trig = 0;
int dist1 = 0;

void setup() {
  pinMode(sensPin, INPUT);
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    for (;;);
  }
  display.clearDisplay();
  display.setTextSize(1.5);
  display.setTextColor(WHITE);
  display.setCursor(0, 10);
  display.display();
}
void loop() {
  if (digitalRead(sensPin)) {
    T = mags * (millis() - prevTime);
    prevTime = millis();
    u = ((2 * pi * R) / T) * 3600;
    while (digitalRead(sensPin)) disp(u);
  }
  if (digitalRead(sensPin) == HIGH && trig == 2) {
    dist1 += 2 * R * pi;
    trig = 0;
  } else if (digitalRead(sensPin) == HIGH) {
    trig ++;
  }
  if (millis() - prevTime > 4000 / mags) u = 0;
  disp(u);
}

void disp(double U) {
  display.clearDisplay();
  display.setCursor(0, 10);
  display.print("Speed: ");
  display.print(U);
  display.println(" km/h");
  display.print("Distance: ");
  display.print(dist1);
  display.println(" m");
  display.setCursor(0, 10);
  display.display();
}

I'm really not sure what's going wrong, can someone help?

can you post the code that worked ?

while (digitalRead(sensPin)) disp(u);

This is probably not a very good idea.
You are calling a function repeatedly (possibly infinitely) without ever preforming scheduled tasks.
how about just in case you try.

while (digitalRead(sensPin)) {
  disp(u);
  yield();
}
1 Like

Sure, here it is:

/**************************************************************************
  This is an example for our Monochrome OLEDs based on SSD1306 drivers

  Pick one up today in the adafruit shop!
  ------> http://www.adafruit.com/category/63_98

  This example is for a 128x64 pixel display using I2C to communicate
  3 pins are required to interface (two 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,
  with contributions from the open source community.
  BSD license, check license.txt for more information
  All text above, and the splash screen below must be
  included in any redistribution.
 **************************************************************************/

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library.
// On an arduino UNO:       A4(SDA), A5(SCL)
// On an arduino MEGA 2560: 20(SDA), 21(SCL)
// On an arduino LEONARDO:   2(SDA),  3(SCL), ...
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define NUMFLAKES     10 // Number of snowflakes in the animation example

#define LOGO_HEIGHT   16
#define LOGO_WIDTH    16
static const unsigned char PROGMEM logo_bmp[] =
{ 0b00000000, 0b11000000,
  0b00000001, 0b11000000,
  0b00000001, 0b11000000,
  0b00000011, 0b11100000,
  0b11110011, 0b11100000,
  0b11111110, 0b11111000,
  0b01111110, 0b11111111,
  0b00110011, 0b10011111,
  0b00011111, 0b11111100,
  0b00001101, 0b01110000,
  0b00011011, 0b10100000,
  0b00111111, 0b11100000,
  0b00111111, 0b11110000,
  0b01111100, 0b11110000,
  0b01110000, 0b01110000,
  0b00000000, 0b00110000
};

void setup() {
  Serial.begin(9600);

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;); // Don't proceed, loop forever
  }

  // Show initial display buffer contents on the screen --
  // the library initializes this with an Adafruit splash screen.
  display.display();
  delay(2000); // Pause for 2 seconds

  // Clear the buffer
  display.clearDisplay();

  // Draw a single pixel in white
  display.drawPixel(10, 10, SSD1306_WHITE);

  // Show the display buffer on the screen. You MUST call display() after
  // drawing commands to make them visible on screen!
  display.display();
  delay(2000);
  // display.display() is NOT necessary after every single drawing command,
  // unless that's what you want...rather, you can batch up a bunch of
  // drawing operations and then update the screen all at once by calling
  // display.display(). These examples demonstrate both approaches...

  testdrawline();      // Draw many lines

  testdrawrect();      // Draw rectangles (outlines)

  testfillrect();      // Draw rectangles (filled)

  testdrawcircle();    // Draw circles (outlines)

  testfillcircle();    // Draw circles (filled)

  testdrawroundrect(); // Draw rounded rectangles (outlines)

  testfillroundrect(); // Draw rounded rectangles (filled)

  testdrawtriangle();  // Draw triangles (outlines)

  testfilltriangle();  // Draw triangles (filled)

  testdrawchar();      // Draw characters of the default font

  testdrawstyles();    // Draw 'stylized' characters

  testscrolltext();    // Draw scrolling text

  testdrawbitmap();    // Draw a small bitmap image

  // Invert and restore display, pausing in-between
  display.invertDisplay(true);
  delay(1000);
  display.invertDisplay(false);
  delay(1000);

  testanimate(logo_bmp, LOGO_WIDTH, LOGO_HEIGHT); // Animate bitmaps
}

void loop() {
}

void testdrawline() {
  int16_t i;

  display.clearDisplay(); // Clear display buffer

  for (i = 0; i < display.width(); i += 4) {
    display.drawLine(0, 0, i, display.height() - 1, SSD1306_WHITE);
    display.display(); // Update screen with each newly-drawn line
    delay(1);
  }
  for (i = 0; i < display.height(); i += 4) {
    display.drawLine(0, 0, display.width() - 1, i, SSD1306_WHITE);
    display.display();
    delay(1);
  }
  delay(250);

  display.clearDisplay();

  for (i = 0; i < display.width(); i += 4) {
    display.drawLine(0, display.height() - 1, i, 0, SSD1306_WHITE);
    display.display();
    delay(1);
  }
  for (i = display.height() - 1; i >= 0; i -= 4) {
    display.drawLine(0, display.height() - 1, display.width() - 1, i, SSD1306_WHITE);
    display.display();
    delay(1);
  }
  delay(250);

  display.clearDisplay();

  for (i = display.width() - 1; i >= 0; i -= 4) {
    display.drawLine(display.width() - 1, display.height() - 1, i, 0, SSD1306_WHITE);
    display.display();
    delay(1);
  }
  for (i = display.height() - 1; i >= 0; i -= 4) {
    display.drawLine(display.width() - 1, display.height() - 1, 0, i, SSD1306_WHITE);
    display.display();
    delay(1);
  }
  delay(250);

  display.clearDisplay();

  for (i = 0; i < display.height(); i += 4) {
    display.drawLine(display.width() - 1, 0, 0, i, SSD1306_WHITE);
    display.display();
    delay(1);
  }
  for (i = 0; i < display.width(); i += 4) {
    display.drawLine(display.width() - 1, 0, i, display.height() - 1, SSD1306_WHITE);
    display.display();
    delay(1);
  }

  delay(2000); // Pause for 2 seconds
}

void testdrawrect(void) {
  display.clearDisplay();

  for (int16_t i = 0; i < display.height() / 2; i += 2) {
    display.drawRect(i, i, display.width() - 2 * i, display.height() - 2 * i, SSD1306_WHITE);
    display.display(); // Update screen with each newly-drawn rectangle
    delay(1);
  }

  delay(2000);
}

void testfillrect(void) {
  display.clearDisplay();

  for (int16_t i = 0; i < display.height() / 2; i += 3) {
    // The INVERSE color is used so rectangles alternate white/black
    display.fillRect(i, i, display.width() - i * 2, display.height() - i * 2, SSD1306_INVERSE);
    display.display(); // Update screen with each newly-drawn rectangle
    delay(1);
  }

  delay(2000);
}

void testdrawcircle(void) {
  display.clearDisplay();

  for (int16_t i = 0; i < max(display.width(), display.height()) / 2; i += 2) {
    display.drawCircle(display.width() / 2, display.height() / 2, i, SSD1306_WHITE);
    display.display();
    delay(1);
  }

  delay(2000);
}

void testfillcircle(void) {
  display.clearDisplay();

  for (int16_t i = max(display.width(), display.height()) / 2; i > 0; i -= 3) {
    // The INVERSE color is used so circles alternate white/black
    display.fillCircle(display.width() / 2, display.height() / 2, i, SSD1306_INVERSE);
    display.display(); // Update screen with each newly-drawn circle
    delay(1);
  }

  delay(2000);
}

void testdrawroundrect(void) {
  display.clearDisplay();

  for (int16_t i = 0; i < display.height() / 2 - 2; i += 2) {
    display.drawRoundRect(i, i, display.width() - 2 * i, display.height() - 2 * i,
                          display.height() / 4, SSD1306_WHITE);
    display.display();
    delay(1);
  }

  delay(2000);
}

void testfillroundrect(void) {
  display.clearDisplay();

  for (int16_t i = 0; i < display.height() / 2 - 2; i += 2) {
    // The INVERSE color is used so round-rects alternate white/black
    display.fillRoundRect(i, i, display.width() - 2 * i, display.height() - 2 * i,
                          display.height() / 4, SSD1306_INVERSE);
    display.display();
    delay(1);
  }

  delay(2000);
}

void testdrawtriangle(void) {
  display.clearDisplay();

  for (int16_t i = 0; i < max(display.width(), display.height()) / 2; i += 5) {
    display.drawTriangle(
      display.width() / 2  , display.height() / 2 - i,
      display.width() / 2 - i, display.height() / 2 + i,
      display.width() / 2 + i, display.height() / 2 + i, SSD1306_WHITE);
    display.display();
    delay(1);
  }

  delay(2000);
}

void testfilltriangle(void) {
  display.clearDisplay();

  for (int16_t i = max(display.width(), display.height()) / 2; i > 0; i -= 5) {
    // The INVERSE color is used so triangles alternate white/black
    display.fillTriangle(
      display.width() / 2  , display.height() / 2 - i,
      display.width() / 2 - i, display.height() / 2 + i,
      display.width() / 2 + i, display.height() / 2 + i, SSD1306_INVERSE);
    display.display();
    delay(1);
  }

  delay(2000);
}

void testdrawchar(void) {
  display.clearDisplay();

  display.setTextSize(1);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw white text
  display.setCursor(0, 0);     // Start at top-left corner
  display.cp437(true);         // Use full 256 char 'Code Page 437' font

  // Not all the characters will fit on the display. This is normal.
  // Library will draw what it can and the rest will be clipped.
  for (int16_t i = 0; i < 256; i++) {
    if (i == '\n') display.write(' ');
    else          display.write(i);
  }

  display.display();
  delay(2000);
}

void testdrawstyles(void) {
  display.clearDisplay();

  display.setTextSize(1);             // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE);        // Draw white text
  display.setCursor(0, 0);            // Start at top-left corner
  display.println(F("Hello, world!"));

  display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Draw 'inverse' text
  display.println(3.141592);

  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(SSD1306_WHITE);
  display.print(F("0x")); display.println(0xDEADBEEF, HEX);

  display.display();
  delay(2000);
}

void testscrolltext(void) {
  display.clearDisplay();

  display.setTextSize(2); // Draw 2X-scale text
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(10, 0);
  display.println(F("scroll"));
  display.display();      // Show initial text
  delay(100);

  // Scroll in various directions, pausing in-between:
  display.startscrollright(0x00, 0x0F);
  delay(2000);
  display.stopscroll();
  delay(1000);
  display.startscrollleft(0x00, 0x0F);
  delay(2000);
  display.stopscroll();
  delay(1000);
  display.startscrolldiagright(0x00, 0x07);
  delay(2000);
  display.startscrolldiagleft(0x00, 0x07);
  delay(2000);
  display.stopscroll();
  delay(1000);
}

void testdrawbitmap(void) {
  display.clearDisplay();

  display.drawBitmap(
    (display.width()  - LOGO_WIDTH ) / 2,
    (display.height() - LOGO_HEIGHT) / 2,
    logo_bmp, LOGO_WIDTH, LOGO_HEIGHT, 1);
  display.display();
  delay(1000);
}

#define XPOS   0 // Indexes into the 'icons' array in function below
#define YPOS   1
#define DELTAY 2

void testanimate(const uint8_t *bitmap, uint8_t w, uint8_t h) {
  int8_t f, icons[NUMFLAKES][3];

  // Initialize 'snowflake' positions
  for (f = 0; f < NUMFLAKES; f++) {
    icons[f][XPOS]   = random(1 - LOGO_WIDTH, display.width());
    icons[f][YPOS]   = -LOGO_HEIGHT;
    icons[f][DELTAY] = random(1, 6);
    Serial.print(F("x: "));
    Serial.print(icons[f][XPOS], DEC);
    Serial.print(F(" y: "));
    Serial.print(icons[f][YPOS], DEC);
    Serial.print(F(" dy: "));
    Serial.println(icons[f][DELTAY], DEC);
  }

  for (;;) { // Loop forever...
    display.clearDisplay(); // Clear the display buffer

    // Draw each snowflake:
    for (f = 0; f < NUMFLAKES; f++) {
      display.drawBitmap(icons[f][XPOS], icons[f][YPOS], bitmap, w, h, SSD1306_WHITE);
    }

    display.display(); // Show the display buffer on the screen
    delay(200);        // Pause for 1/10 second

    // Then update coordinates of each flake...
    for (f = 0; f < NUMFLAKES; f++) {
      icons[f][YPOS] += icons[f][DELTAY];
      // If snowflake is off the bottom of the screen...
      if (icons[f][YPOS] >= display.height()) {
        // Reinitialize to a random position, just off the top
        icons[f][XPOS]   = random(1 - LOGO_WIDTH, display.width());
        icons[f][YPOS]   = -LOGO_HEIGHT;
        icons[f][DELTAY] = random(1, 6);
      }
    }
  }
}

I will try the edits you suggested and get back to you

Ok, so it worked (it was a power supply problem, not anything else.)

Why is the solution not the power supply then.

well, for one thing I tested it after I changed the power supply AND code, and I am not positive as to which it is. I have also seen people get offended if you mark up your own post as a solution. The main reason was that I was not sure whether it was a power supply problem or a code problem though.