display.begin() always true

[NuclearPhoenixx]

Hi there! I have an issue where the display.begin() function will always return true regardless if there is an actual display plugged in or not. It works fine if there is a display, of course, but if there is none it doesn't register that and thinks there still is one.

• Arduino board: Raspberry Pi Pico with arduino-pico core

• Arduino IDE version (found in Arduino -> About Arduino menu): 2.0.1

• List the steps to reproduce the problem below (if possible attach a sketch or
  copy the sketch code in too):

  • Load the ssd1306_128x64_i2c example.
  • Upload.
  • Serial.println(F("SSD1306 allocation failed")); will never show because display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS) will never be false.
  • That's literally it for me. Nothing more, that easy.

Maybe it's got something to do with the Raspberry Pi Pico? I don't think so tbh, because everything else works fine, so there must be an issue here.

[nyckidryan]

I can confirm this is the case on ESP32-WROOM-32 38 pin dev module as well, in Arduino IDE 1.8.19 and 2.0.1.

[PitHerm]

Yes, i display.begin returns always TRUE
on Pi Pico , ESP8266 , ESP32

[PitHerm]

Well, i digged around within the source code of the lib and found NO return of FALSE if the display is not avaiable !

I thought about a workaround and here is the tested and working result:
Wire.begin();
Wire.beginTransmission (SCREEN_ADDRESS);
if (Wire.endTransmission () > 0){
Serial.println("SSD1306 allocation failed");
for(;;); // Don't proceed, loop forever
}
Wire.end();
if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
Serial.println(F("SSD1306 FAIL: Buffer allocation error, not enough memory"));
for(;;); // Don't proceed, loop forever
}

instead of:
if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
Serial.println(F("SSD1306 allocation failed"));
for(;;); // Don't proceed, loop forever
}

Additional Info:

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

works but NOT as expected , it only returns FALSE if not enough memory for display buffer is avaiable.
so it would be better to change the phrase " Serial.println(F("SSD1306 allocation failed")); " to
" Serial.println(F("SSD1306 FAIL: Buffer allocation error, not enough memory")); "