Hi,
As per the chip configuration (Chapter 8 - Table 8-13. FlexBus Multiplexing) and signal multiplexing (Chapter 4 - Table 4.1 Pinouts) sections in the Vybrid reference Manual , FB_CS4_b signal is not listed for Vybrid Chip.
karinavalencia - The behaviour of writing to FB_CSAR4, FB_CSMR4, FB_CSCR4 registers is not documented in the reference manual, could you please ask one of the Freescale Applications Engineers to confirm the same.
Thanks,
Timesys Support