50g freezes on SD card access

[Claudio L.]

(01-10-2020 04:01 PM)Eric Rechlin Wrote:  Use a PC to format the card, not the calculator.


You can use either FAT32 or FAT16, but I recommend FAT16. Picking FAT16 will give larger cluster sizes, which means you can fit fewer files on the card (though the reduction in limit is not meaningful for any typical use), because each file will take more size, but it also reduces the number of clusters on the card, which avoids the slow-power-on issues with large cards.

As I recall, FAT32 will use 8 times as many clusters as FAT16 with the default Windows cluster size, so the power-on delay is 8 times longer (which is effectively a couple seconds for a 2 GB card with FAT32 vs imperceptible with FAT16, if I remember right). I do not remember how the calculator handles non-standard cluster sizes.

Just wanted to add the bootloader can only read FAT16. This only means FAT16 is needed to update firmware via SD card. Everything else will work fine on FAT32.

(01-10-2020 04:01 PM)Eric Rechlin Wrote:  I believe the SD vs SDHC limit is in software, not hardware, however, so I think it is theoretically possible that something with its own SD card implementation like newRPL could support larger capacity SDHC (or maybe even SDXC) cards but I don't know whether that is realistic.

You are correct. The only difference between SD and SDHC is in software and newRPL supports SDHC cards, larger capacity is fine (although it raises the question: what for?), multiple partitions are fine, etc.
SDXC has a new high speed protocol for faster data transmission and 1.8V support, that's not supported by the hardware in the calculator (all decent cards, however, should offer a fallback mechanism to the old spec). Also, they have a different way to count sectors, since the number of sectors exceeds the 32 GB limit on SDHC. This is all in the SD 3.0 specification, but that could in theory be managed by software if the need arise. At this point, newRPL does not support SDXC cards, only SDHC (SD 2.0 specification).