Panasonic F77G User Manual page 426

Chapter 12 Serial Interface 3
It is possible to shut down the communication. When the communication should be stopped
by force, set the SC3SBOS and the SC3SBIS of the SC3MD1 register to "0".
Setup for each flag should be done in order. The activation of communication should be done
after all control registers (except table 13-2-1 : SC3TRB) are set.
The SC3CKS register should set the transfer clock so that the transfer rate is "under 400
kHz".
To detect start condition, connect the SBO3/SBI3 pins to be 2
puts/outputs serial data.
At communication, select Nch-open drain for the pin type, because the bus should be
switched to be used/released by the hardware. And even at the reception, select the SDA pin
(the SBO3 pin) direction control to "output".
XII - 40
Operation
channels
. The SDA pin in-