Can I use the ADuC842 in an I2C-multimaster environment?
The ADuC842 does not implement I2C master mode in hardware. You need to write
the software to implement the code. See Application note uC001 at
Page 7 of this application note states clearly that it is not possible to
readback the status of SCL or SDA pins unless MDE is low (configured as an
input). Therefore you need to build in the multimaster functionality into your
software master by using extra input pins.