Machine reset after drop

Post here to share useful tips and tricks, to ask questions about using your DM42 or to report software-related problems
Post Reply
Dave Britten
Posts: 46
Joined: Wed Jun 14, 2017 7:27 pm

Machine reset after drop

Post by Dave Britten » Mon Oct 22, 2018 12:04 pm

And by "drop", I mean a physical drop, face down on the pavement (because I'm a bonehead). It was still in the case, so it appears to be perfectly fine. However the sudden G-forces caused the device to reset, thus loading the most recent state saved in flash, which was about 2 days old. The date and time were still correct, which makes me think the SRAM retained its contents. Perhaps the reset routine could be enhanced to include something like the dreaded HP 48 "Try to recover memory?" and just run the current program with whatever happens to be in memory? Maybe with a few basic consistency checks to detect major corruption.

User avatar
Walter
Posts: 793
Joined: Tue May 02, 2017 9:13 am
Location: Close to FRA, Germany

Re: Machine reset after drop

Post by Walter » Mon Oct 22, 2018 1:45 pm

Dave Britten wrote:
Mon Oct 22, 2018 12:04 pm
However the sudden G-forces caused the device to reset...
I can only imagine "the sudden G-forces" causing an interrupt in voltage supply due to a short loss of contact - which in turn caused a reset. Beyond this, the effect of gravity on electrons should be negligible.

Edited to correct an error in a foreign language.
Last edited by Walter on Mon Oct 22, 2018 2:59 pm, edited 1 time in total.
DM42 SN: 00041 --- Follower of Platon.

HP-35, HP-45, ..., HP-50, WP 34S, WP 31S, DM16L

HPMike
Posts: 67
Joined: Fri Jul 21, 2017 9:01 pm
Location: DFW, Texas

Re: Machine reset after drop

Post by HPMike » Mon Oct 22, 2018 2:29 pm

I only use my calculators when standing over thick carpet.
DM15L, S/N 00548. DM42, SN: 00159.

User avatar
akaTB
Posts: 214
Joined: Tue May 02, 2017 11:56 am

Re: Machine reset after drop

Post by akaTB » Mon Oct 22, 2018 2:56 pm

HPMike wrote:
Mon Oct 22, 2018 2:29 pm
I only use my calculators when standing over thick carpet.
To kill them by ESD? ;)
Greetings,
    Massimo

-+×÷ ↔ left is right and right is wrong

Dave Britten
Posts: 46
Joined: Wed Jun 14, 2017 7:27 pm

Re: Machine reset after drop

Post by Dave Britten » Mon Oct 22, 2018 3:12 pm

Walter wrote:
Mon Oct 22, 2018 1:45 pm
Dave Britten wrote:
Mon Oct 22, 2018 12:04 pm
However the sudden G-forces caused the device to reset...
I can only imagine "the sudden G-forces" causing an interrupt in voltage supply due to a short loss of contact - which in turn caused a reset. Beyond this, the effect of gravity on electrons should be negligible.

Edited to correct an error in a foreign language.
That was my assumption too. The battery probably bounced away from the contacts for just a moment. Which makes me wonder if I could solder a small 3V cap across the two battery lines to smooth out such brief losses of power. If I did, I would just take it on faith that it works, rather than repeatedly dropping the calculator on pavement to confirm. :D

User avatar
Walter
Posts: 793
Joined: Tue May 02, 2017 9:13 am
Location: Close to FRA, Germany

Re: Machine reset after drop

Post by Walter » Mon Oct 22, 2018 3:35 pm

Dave Britten wrote:
Mon Oct 22, 2018 3:12 pm
The battery probably bounced away from the contacts for just a moment. Which makes me wonder if I could solder a small 3V cap across the two battery lines to smooth out such brief losses of power. If I did, I would just take it on faith that it works, rather than repeatedly dropping the calculator on pavement to confirm. :D
:lol: Recommended ;)
DM42 SN: 00041 --- Follower of Platon.

HP-35, HP-45, ..., HP-50, WP 34S, WP 31S, DM16L

Logan
Posts: 20
Joined: Sat Jul 08, 2017 11:03 pm

Re: Machine reset after drop

Post by Logan » Mon Oct 22, 2018 3:57 pm

Dave Britten wrote:
Mon Oct 22, 2018 3:12 pm
Which makes me wonder if I could solder a small 3V cap across the two battery lines to smooth out such brief losses of power.
You could do that Dave. Or you could just, you know, not drop your calculator :D
DM42 SN 210

Dave Britten
Posts: 46
Joined: Wed Jun 14, 2017 7:27 pm

Re: Machine reset after drop

Post by Dave Britten » Mon Oct 22, 2018 5:24 pm

Logan wrote:
Mon Oct 22, 2018 3:57 pm
Dave Britten wrote:
Mon Oct 22, 2018 3:12 pm
Which makes me wonder if I could solder a small 3V cap across the two battery lines to smooth out such brief losses of power.
You could do that Dave. Or you could just, you know, not drop your calculator :D
That would be my Plan A. But I find it never hurts to have a good Plan B. ;)

Could also be useful for doing a battery change without clearing memory, if it's a big enough cap (no idea how to size for that since I'm not an EE).

Post Reply