Thank you so much @katak255. Indeed the 7-pin OLED board was set to SPI not I2C, and your link made me realise that. Now I can use it. ThanksThe other possibility is that the interface mode need to be set. The boards have one of the two enabled. In the following link, a similar board need changes to jumpers:
!Statistics: Posted by eucalypt — Sun Jan 19, 2025 12:48 am