Hi,

I have been looking at using either SD Flash or Micro SD Flash on a
system which logs a fair amount of data. However this system will be
mounted on a vehicle so it will see a certain amount of shock and
vibration. I have been searching for SD and Micro SD sockets, and have
found a few, but I have been unable to found a manufacturer that
actually lists information on what sort of shock and vibration levels
will start to cause problems with accessing the flash device.
Any pointers to such info would be greatly appreciated.

Regards
Anton Erasmus

On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
Good luck on that one. I have worked off and on in defense for many
years and I have seldom found vendors of low cost/high volume
commercial components much interested in providing the sort of data
required. You will likely have to do your own testing for this. One
thing I would recommend is that you provide your own mechanical card
retention. The rest of the connector is likely to work well as long
as the case is sealed from the environment.

Oh yeah, be sure to select a vendor that uses gold over nickle plating
on the contacts. I assume you can find this in a low end commercial
product. Otherwise you are likely to see premature failures.

rickman wrote:

If the data logger is small enough, wrap it up in styraform and rubber
shock mounts.

Logomatic Serial SD Datalogger:
http://www.sparkfun.com/commerce/pro...roducts_id=752

donald

On Feb 12, 3:05 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:

That is at least partly because it is HEAVILY dependent on the
mechanical design of your device. It's also slightly dependent on the
orientation of the device.

The SD family of devices have relatively low mass and the connectors
have a fairly high contact force. Use push-pull connectors by
preference (push-push may self-eject accidentally), and provide an
external mechanical lock to prevent the card from sliding out.This
need not be anything more complicated than a screw running through the
PCB.

On 12 Feb 2007 19:06:35 -0800, "larwe" <zwsdotcom@gmail.com> wrote:

I realise this, but was hoping to get either some figures, or
experience from others. What sort of filtering do the actual SD
Flash devices provide on their inputs ? Would the lower speed devices
be more noise immune ? i.e. Less likely to "see" a glitch caused by a
connect-disconnect-connect sequence caused by a shock ?

I have been searching to find vendors where one can easily buy these
sockets in low quantities. So far I have found only RS-Componets where
one can buy one-off without problems.

Regards
Anton Erasmus

On Feb 13, 2:38 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
I found some data at Digikey. They sell at least three brands, 3M,
AVX and Molex. The Molex data sheet shows vibration and shock data...

This will not format here, but you get the idea...

4 Vibration
Mate dummy card and subject to the
following vibration conditions, for a
period of 2 hours in each of 3 mutually
perpendicular axis, passing DC 1mA
during the test.
Amplitude: 1.5mm P-P or 49m/s2
Frequency: 10-55-10 Hz
Shall be traversed in 20 minute.
(EIA 364-28 Condition 1)
Appearance: No damage.
Contact resistance: 80m
MAX.
Discontinuity: 100 Nanosecond
max.
5 Shock
(Mechanical)
Mate a dummy card and subject to the
following shock conditions. 3 shocks shall
be applied along 3 mutually perpendicular
axis, passing DC 1 mA current during the
test.
(Total of 18 shocks)
Test pulse: Half Sine
Peak value: 980 m/s2 {100G}
Duration: 6 millisecond
(EIA 364-27 Condition C)
Appearance: No damage.
Contact resistance: 80m
MAX.
Discontinuity: 0.1 microsecond
MAX.


They do seem to allow for 100 ns of disconnection on the contacts.
That could be significant if you are operating at the time.

I searched on SD Card and then weeded out irrelevant stuff.

On 13 Feb 2007 12:14:44 -0800, "rickman" <gnuarm@gmail.com> wrote:


Thanks,

I found only one Micro SD connector on Digikeys site. (3M). The
vibration stuff from Molex is for Mini SD. I did find Micro SD
connectors on Molex's own site, but the only data I could get on these
were mechanical drawings. Since the Micro SD is quite a bit smaller
and lighter than the Mini SD, I would expect at worst the same results
as the Mini SD, and probably better. It looks like one would be able
to use these smaller flash cards in quite harsh environments - shock
and vibration wise.

Regards
Anton Erasmus

On Feb 14, 2:22 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
I find it odd that they spec a 100 nanosecond disconnect time during
the test. Will your application tolerate such a disconnection?

You might be able to get the specs you need if you contact the
manufacturers. They often have done various testing, but only make
the results available on request.