Run mDDR at 24MHz on i.MX28

[clementøstergaa]

Has anyone here got any experience running the MT46H64M16LF mDDR at 24 MHz on a i.MX28?

Currently, using the timing from MX28_mDDR_register_programming_aid_v0.4, it can run at 48MHz.

When switching to 32 MHz or 24MHz, it hangs.

The plan is to be able to disable the PLL and still have the system running at 24MHz from the xtal.

[AnsonHuang · Accepted solution]

Hi, Clement

     Our linux BSP should support mDDR running at 24MHz, but may not on same type of mDDR chip, you can refer to our BSP, I think the issue you met should be related to mDDR's setting, as different ddr chip may need different setting. If you have i.MX28 EVK board, you can try it first.

[clementøstergaa]

Hi

I tried the settings from the BSP, and this time they worked.

Comparing it with the configuration from the spread sheet, I have determined that the problem was the DRAM control registers 87,88,91 and 92, which apparently needs to be set to different values when running at 24 MHz.