Hi,
I've TUSB3210 MCU. It loads the program from serial EEPROM at startup. I've tred to implement in-circuit programming of this EEPROM. MCU strongly pulls SCL to 1 when program is loaded to chip. As result, I can't drop it lower than 2.5v from LPT open-collector output! Manufacturer mentions that MCU's SCL is push-pull output. SDA line of MCU is normal a open collector. IMO, incorrect line type of SCL line neglects the whole idea of i2c.
Why did they implement SCL as a push-pull and what does it mean? Is it normal for i2c device to block the bus?