Is it possible to bit bang the I2C pins on my Zero? - Project Guidance - Arduino Forum
Bit-banged I2C timing » JeeLabs
GitHub - tobajer/i2cbitbang: The bit-banging version of i2c for STM32F4 with possibility to create many i2c ports (limited by GPIO number). It supports clock stretching and different speeds according to standards.
I2C Bit-Banging on STM32F103 - STMicroelectronics Community