WP 34S and 31S bugs and fixes

[efroymson]

I am not concerned about it happening again, now that I know what to look for. I will only point out that what you are saying here seems to contradict what Paul Dale said, about the BATT command not being accurate. Also, I don't recall seeing a low battery indicator on my screen while this behavior was occurring.

It seems to me that I saw somewhere that the voltage the calculator is looking for 2.7V? Mine read 2.9V and still had the problem.

I agree that having the BATT command work as I suggest would consume some power, but it would only do so on the request of the user ... I wouldn't think it a good idea to check automatically at power-on, as it might cause it to immediately switch off again (though that would presumably trigger the immediate thought "dead battery" in the user who could not get it to switch on).

Is this a unique problem to the WP-34S? Is it related to the combination of a wide variety of operations, some of which put a much higher burden on the processor than others? I'm thinking that this essentially could not have happened on an old HP-35 from the 1970s, since it used so much power to operate the display, and the computing part was capped at the level of the trig operations ...

I ramble.

(02-07-2017 02:47 PM)Nick Wrote:  

(02-06-2017 10:41 PM)efroymson Wrote:  May I make the humble suggestion that the BATT command be altered to actually provide some useful information? As it stands, it is worse than useless. Perhaps it could check the voltage it sees on wakeup, then run a few calculations to get the processor going, and check again? If it notices a drop in voltage, it could report "Replace Batteries" even, since there is an alphanumeric display. Alternatively (additionally?) is there any way for the calculator to know if it has shut down due to a low voltage condition? I thought I saw it say "Bye" at least once when it had the weak batteries. If so, that could be checked by the BATT command, and the same message given.

Such a test would consume power and a low battery indicator is built-in (see below).

You can perform the test you're asking for by inserting the BATT command into an intensive program / loop and have it periodically (not continually so that it doesn't pause the workload) update the display with the voltage. That will output the voltage "under load".

Normally, the calculator goes into SLOW mode if the voltage gets low and display a battery icon (not sure if they're tied together). You'll notice this first during intensive calculation then the calculator will return to normal. [Advanced: You can add a check for SLOW in a battery test routine to observe the same. It's not a built-in function like BATT, you'll have to test bit 59 of STOM if you'd like to explore this behavior.]

The calculator remains stable as the batteries go weak and can run in SLOW long before shut-down, so this could just have been bad batteries -- I wouldn't be concerned with it happening again.