In setting up the I2C mode on a 16c73a for a slave, the TRISC bit for the
SDA and SCL line are configure as input; also the corresponding PORTC
latches are cleared. However when I check with a scope, I found out that
these open drain collector output a voltage (+5V) on the bus masking the
signal from the master. I don't know what I am doing wrong but this seem
weird.
The master definitely works because I clearly can see the start condition on
the scope. The slaves won't respond because when they are connected on the
bus they output a high level all the time.
What am I doing wrong? Should I post the code that I use to initialize the
SSPCON?
What are pull up resistors anyway?
Thank you for prompt replies it is very important to me as I need to
complete my school project by next week.

Franck D Rougier