TI Team,
We have finalized the setup of the AM3505 with LPDDR memory from Micron (part #MT46H16M32LFB5-6 IT:C TR). Although we have booted Linux successfully at room temperature, the boot process has failed at elevated temperatures. Our questions are as follows:
- Can you provide working parameters that will allow our system to operate over extended temperature (-25--85 C)
- See attached emif4.h and emif4.c files we currently use (ideally, if we could get recommendations from TI on how to optimize these files for the temperature range we are operating at
- Can you elaborate on VTP calibration and how it impacts system performance our operating temperatures
- From our testing, it is clear that VTP compensation is required when the external memory strobe is enabled to ensure Linux bootup
- Why is it necessary to set the CTRL_DEVCONF3_DDR_CMOSEN to 1 per the recommendations for mddr / LPDDR memory. If this is left at 0, we start getting memory errors when the chip temperatures exceed ~60C (as measured by an IR thermometer)
- Why is that when we set the REG_SDRAM_DRIVE to 1/2 drive strength from full drive strength, as recommended for LPDDR, there is no effect on our system?
- Can you elaborate on the EMIF controller operation particularly when the interface memory contains a status register for the multiplier of the REFI signal based on the chip temperature. Again, we are using Micron LPDDR memory.
- Does the EMIF controller pay any attention to this type of register? We have seen to effect on system performance if we reduce the refresh by four
Again, we are new to this, so if you have any information that can help us here that would be great. Certainly, we welcome an recommendations you have outside of the external st-robbing that would help us design a more robust LPDDR interace.
-David
