50g freezes on SD card access

[tuxfish]

Hi,

SDcards are known to be able to freeze other devices like cameras, hi-fi systems, pc as well.

When this happens, nothing but a hard reset of the device helps.
The reasons why this freeze occurs varies and stays a bit cloudy.

IMO fat16 format is a "must" with SDcards used in conjuction with an HP50g.
fat32 format is no good at all: at best the access time will be much slower, at worst the whole card will not work.

The capacity of the SDcard must not exceed 2GB.
In my experience SDcards with one GB work in most cases even better.
1 GB are officially supported by the HP 50g; 2GB might work.

The bus speed should be 12.5 or 25 MB/s.

SDcards come in five card families:
the original Standard-Capacity (SDSC, 128MB-2GB, fat16),
the High-Capacity (SDHC, 2GB-32GB, fat32),
the eXtended-Capacity (SDXC, 32GB-2TB, fat32/exFAT),
the Ultra-Capacity (SDUC, 2TB-128TB, exFAT)
N.N.

Only the original Standard-Capacity (SDSC) with <= 2GB will work in an HP 50g.
SDHC, SDXC & SDUC will not do.

Instead of using a microSD with adaptor the old large card format tends to work best.

In my HP 50g a K*n*s*o* 1GB and a S*N*I*K 2GB SCSC work fine.
Both cards are fat16 and in the old large "full size" format (no adaptor).

UHS-I,-II, -III or express will not work (bus speed too high).

In general there is much more going on when a SDcard communicates with a device.

There is no open spec, but at least three cases are known, in which the controller shuts down the SDcard explicitly (has to do so in order to comply with the spec):
1) wrong format (e.g. fat32 with SDSC)
2) some timing error at the beginning of the interaction between card and controller.
3) bus speed too high; no common one

What could be done now ?

* clean contacts in calculator & SDcard with isopropyl alcohol (pharmacy)
* try a SDSC with max 1GB capacity in "full size" from another vendor
* try to find out more about the format of the SDcards that cause the freeze:
fat16 or fat32 alone is not enough. What is the sector size ? Partition type 06h ?
A controller and/or firmware may freeze if confronted with the wrong block size.
* try to borrow a working SDcard from another HP50g-user nearby.
It should work without a flaw.
* delete lost.dir or any other file on the SDcard if you do not need the file anymore.
A corrupt file might also cause a "freeze".

In some cases a corrupted SDcard can be repaired with CHKDSK (win) or Disk Utility (MacOS) or better with the "SD Memory Card Formatter"
But beware: formatting destroys data.

Good luck !