i2c LC1602 display drived by STM32F103

I wanted to use STM32F103 instead Arduno Mega for a radio with TEF6686 (see details at https://nicuflorica.blogspot.com/2020/02/radio-cu-tef6686.html).

First, I tested classical sketch named i2_scanner but I received no device or error at all adresses beginning with 0x01.

I search on internet and I found an interesting article STM32 I2C SCANNER. Because informations from there are too much and must read carefully, I change directly Arduino mega with STM32F103. I saw logo info on display and than nothing. I realised STM32 send correctly i2c comands to device, ut not understand messages from any device. LCD1602 (or LCD2004) need just commands, so can be used.

I tested with LCD1602 powered fron external 5V and STM32 board with 3.3V from USB-FTDI interface

or through USB using internal voltage regulator.

Schematic is as in article from https://controllerstech.com/i2c-lcd-in-stm32/

I made amovie using sketch from https://github.com/tehniq3/STM32F103C8/blob/master/STM32F103_i2c_LCD1602.ino (also here)