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Vybrid LPDDR2 Configuration

Question asked by Eric Averill on Apr 9, 2015
Latest reply on Oct 1, 2015 by Eric Averill



We're using a Winbond W97AH6KBVX2I TR device in our product along with a Vybrid MVF51NN151. I'm attempting to update a LPDDR2 configuration file provided to us by Freescale and am running into some issues related to undocumented registers:

1. We currently have CR110 set to 0x00002020. The reference manual states that for LPDDR2 bits 16:0 have no meaning and should be set to 0, the reset default. When I try this setting our PHY calibration routine fails and the system does not boot correctly. Do these bits have some effect with LPDDR2? It would seem so.

2. We have additional registers, CR38, CR39, CR41, CR125, and CR131 which are labeled in the reference manual as reserved read-only but are being written in the code we were provided. If I remove these writes the memory no longer gets initialized correctly and the system won't boot.

I'm attempting to optimize memory timing as well as perform a general review to ensure that we are configuring the memory and memory controller correctly. Can you provide guidance on these registers?