ST75256 i2c bus mode

[elektronek]

Hello Olikraus,
thanks for reading, i'm testing display type see URL
https://www.winstar.com.tw/products/cog-lcd-module-display/256x128-lcd.html

driver identified as ST75256, switched in i2c mode, scanner found it at 0x3C address,
but not working, display is empty, not showed any pixel, my constructor is below:

#include <Arduino.h>
#include <U8g2lib.h>
#include <Wire.h>

U8G2_ST75256_WO256X128_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);

void setup()
}
u8g2.setI2CAddress(0x3C);
u8g2.begin();
// u8g2.setContrast(128); // try to change contrast
}

void loop() {
u8g2.clearBuffer(); // clear the internal memory
u8g2.setFont(u8g2_font_ncenB08_tr); // choose a suitable font
u8g2.drawStr(10,10,"Hello World!"); // write something to the internal memory
u8g2.sendBuffer(); // transfer internal memory to the display
delay(1000);
}

Do you have please any suggestions ?
Other devices on this i2c (eeprom on 0x50) working correctly
U8g2 latest stable version, ESP32 board

Best Regards!
Martin

[olikraus]

I think you need to use "u8g2.setI2CAddress(0x3C*2);".
As mentioned in the wiki, the i2c address has to be multiplied by 2: https://github.com/olikraus/u8g2/wiki/u8g2reference#seti2caddress

It might be odd and you will find a lot of discussion here in the issues whether the multiplication makes sense or not.

[elektronek]

Thank you very much, now working OK

Martin