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OLED I2C adress

Posted: 19 Nov 2022, 12:44
by CT8ACA
Hello guys,

As I noticed, there are OLED displays with different I2C addresses. Maybe this is my problem, because after installing the bootloader with the ISP programmer, the display shows nothing (no serialnumber).

However, the display works and has the I2C address 0x78. There are also OLEDs with an I2C address of 0x3C.

Is it possible that the bootloader on the DL2MAN (tru)sdx homepage needs a display with the address 0x3C?

With kind regards
Wolfi (Lobo), CT8ACA

Re: OLED I2C adress

Posted: 19 Nov 2022, 13:22
by dl6sez
Hello OM,

0x3C is the 7Bit address mode of 0x78 which is 8Bit Address mode (same address).
In I2C the least significant Bit at the transmission is added to the normally 7Bit address,
0 there represents write and 1 represents read.
So if the 0x78 write its pair is 0x79 read is identical to 0x3C in 7Bit address Notation.

I think your OLED has probably a incompatible controller. As far as i remember the normal used controller is the SH1106 in uSDX and here in (tr)uSDX OLEDs.

Have you checked SCL and SData, maybe switched?

73 de Chris