hello
<<MPC5553_MPC5554_RM>> Table 12-3. Signal Properties,required signal RD_WR/ weak pull-up by the SIU_PCRs.Can I set this pin to weak pull-down? To do so, what's the problem?
Pull resistors determine inactive state for the signal in case it is not driven by EBI module. If you pull-down the signal instead of pull-up, it could be interpret as ‘asserted’ state (instead of ‘negated’) by the memory or other device connected to the EBI module.
Thus you have to use recommended setting.