I am using ESP-WROVER-B 16MB Flash modules in my design. We are about to go into production in the coming months.
I see in menuconfig this option:
SPIRAM_2T_MODE
Enable this option to fix single bit errors inside 64Mbit PSRAM.
Some 64Mbit PSRAM chips have a hardware issue in the RAM which causes bit errors at multiple fixed bit positions.
Note: If this option is enabled, the 64Mbit PSRAM chip will appear to be 32Mbit in size.
Applications will not be affected unless the use the esp_himem APIs, which are not supported in 2T mode.
Question 1: Why is this option not enabled by default? Bit errors in the ram seem like a pretty big deal! Any workaround should be applied by default, one would think?
Question 2: I can't find any documentation of this issue outside of menuconfig itself. Are there any other issues to be aware of when enabling 2T mode. Is there a reason why it is not enabled by default, other than the fact that this forbids the use of the himem apis?
Question 3: is there any way to access the upper 32Mb of the PSRAM when the 2T mode is enabled for the lower 32Mb? (say, through a dedicated API, while other PSRAM accesses are frozen/cache disabled?) I don't (yet) need the upper 32Mb but I am curious, if it is forever out of reach.
Thanks
