WP 34S and 31S bugs and fixes

[efroymson]

A bit late? No you are right on time! Apple has been in the news lately with a similar problem:
https://www.digitaltrends.com/mobile/app...o-upgrade/

Of course the Apple problem is different, given the rechargeable battery, and the fact that they are in trouble for a creative solution to the problem of declining battery capacity.

Maybe the WP-34S should do the same? Proactively slow down if the battery voltage is low? My sense is that it would not have helped me, because the old battery looked good to the firmware at startup, but rapidly faded once the intensive computations began. However, if the heartbeat is frequent enough, it maybe could have noticed the drop in V before dying.

Anyway, thanks for chiming in.

(01-20-2018 02:52 PM)Marcus von Cube Wrote:  

(02-08-2017 06:49 AM)Paul Dale Wrote:  Marcus is the battery voltage level expert from the 34S team.

Maybe my answer is a bit late but here it is:

BATT only reports the internal value so it does not consume any additional power for doing the measurement. The value is derived continuously from a circuit that compares the actual supply voltage to a given threshold. To determine the voltage the threshold is modified until a change in the comparator status bit is detected.

Since the answer is not delivered immediately by the hardware, the software has to wait some time before the readout. While the processor is running a heart beat interrupt is active which performs, among other things like the keyboard scan, the voltage measurement.