We're looking to use the FPC401 on our design and looking at the data sheet the device powers up with a default address of 0x1E in 8bit, (0xF in 7bit). Also, the down stream devices are placed at 0xF0 0xF2 0xF4 0xF6 0xF8 0xFA 0xFC 0xFE, which seem to make to the address space in 7bit as 0x78,0x7A,0x7C,0x7E
I was under the impression that these addresses are reserved in I2C space for 10bit or future expansion purposes? Our system will have the FPC401 on a shared I2C bus and I am just worried about potential issues with other devices on the system. We have a mix of IO Expanders, I2C Mux's, TI Retimers and other things on the same bus.
My Initial thought is to write to the FPC401 as soon as possible before accessign the down stream QSFP modules and re-assign it's address, however it is the only device on the bus, so that means it looks like the last one on the chain (CTRL3 and CTRL4 both tied to ground) so is fixed to that I2C mapped address?
I'd appreciate any thoughts.