WP34s Differential Time and shift

[matthiaspaul]

(02-09-2015 11:43 PM)MarkHaysHarris777 Wrote:  I am noticing that the time shift for my WP34s is almost precisely 1 sec fast per day; half minute fast per month (on average). A program can be written which based on the date and 34s time, along with the difference time in a second time piece (input data) could then reset the 34s for correct present time eliminating the shift mostly.

In fact, some decades ago I wrote a small DOS utility named CORRTIME to silently correct the RTC time of a PC on every bootup and further adjust its correction factor whenever the clock was set manually. So, yes, it's definitely doable... ;-)

However, from the electrical design perspective the correct solution is what Katie suggests, "pulling" the crystal with a trimmer cap. (Of course, there are other solutions as well, but they consume more energy and are therefore not well-suited for a calculator powered by coin cells.)

Quote:and whether it would be easy to have the firmware (configurable) be able to adjust for the shift

Hm, a function to receive a time packet from an attached emulator running on a PC (and having an NTP, GPS, DCF77, RDS etc. synchronized time) might be a nice feature. Either by setting a special "synch time" flag and working silently in the background, or by issuing a specific command.

Greetings,

Matthias