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5745b StandbyRAM

Question asked by jingbo wang on Oct 9, 2018

Hi everyone,


We have two development boards,1.MPC5745B designed by ourself  2.DEVKIT-MPC5748G designed by nxp.

1.We use MPC5748G to test the Standby RAM for data retention after enter the standby mode. Because the Reference Manual indicates that Standby RAM is maintained after MCU enter into the standby mode and an external reset occured wake up the MCU. We modify the boot file startup.S to skip the initialization of the Standby RAM ECC during the process.

2.Now we switch to the MPC5745B board, the chip does not work properly during the read data (The phenomenon is that if you access the data in Standby RAM, the program will be stuck.) The phenomenon is not detected in MPC5748G(same code).

3.In the application note AN5114, there is no difference between MPC5745B and MPC5748G in the Standby RAM. We test many ways for this problem. The code can be used for MPC5748G. But when we use the MPC5745B, the code can not run well. We have tried make a new MPC5745B project, the result is same.

Can you help us solve this problem?  is there some related analysis or reference? Thanks.