RTC Calibration program

Contributions to this software library are always welcome. Please ensure that you post program listings rather than .raw files. They give a reasonable idea of what your program does without having to load them into a DM42 and you can also include comments in your code. Check out the following link for a decoder/encoder: http://www.swissmicros.com/dm42/decoder/

You can then copy/paste the listing and post it in "code" tags.
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ijabbott
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Re: RTC Calibration program

Post by ijabbott » Thu Sep 05, 2019 10:33 pm

mcc wrote:
Thu Sep 05, 2019 4:54 pm
For me it is not totally clear from the instruction, whether I have to set the clock each time I do the calibration...
You just need to know how much it has lost or gained since the last calibration, and the date of the last calibration (assuming the current date set on the calculator is correct), and the previous calibration value. I find the easiest way to do that is to set the clock each time, and use the timestamp of the RTCCALIB.CFG file itself to record when it was last calibrated.

Mine has gained an additional 3 seconds in the 29 days since my previous calibration, which is about 1 ppm. So I should probably subtract 1 from my current calibration value and reset the time. I didn't bother with the program to determine this minor adjustment.

Thomas Okken
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Re: RTC Calibration program

Post by Thomas Okken » Sun Oct 06, 2019 11:12 pm

I used the calibration program, and the results are excellent:

I synchronized my DM42 with time.gov at 7:05:00 PM EDT 2019-09-01

19 days later, at 10:24:00 PM EDT 2019-09-20, it was 67 seconds fast

The CALIB program returned value -43; clock re-synchronized

Now, another 16 days later, the clock is slow by less than 1/2 second. That's equivalent to about 10 seconds per year. I could wait a few months for the drift to build up to where I can do a second calibration step, but I don't think I'll bother. :D

grsbanks
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Re: RTC Calibration program

Post by grsbanks » Mon Oct 07, 2019 10:41 am

Thomas Okken wrote:
Sun Oct 06, 2019 11:12 pm
Now, another 16 days later, the clock is slow by less than 1/2 second. That's equivalent to about 10 seconds per year. I could wait a few months for the drift to build up to where I can do a second calibration step, but I don't think I'll bother. :D
The resolution of the correction is probably lower than that anwyay. I.e. if you alter the calibration value by even 1, it'll probably gain over a second in 16 days and end up a bit further out in the opposite direction to the error in there now.
Not SwissMicros staff, just an enthusiast.

HPMike
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Re: RTC Calibration program

Post by HPMike » Thu Oct 24, 2019 1:36 pm

Amazing ! Over a month has passed since I made the last calibration and there is no discernible change in the time setting when compared to my atomic watch. IOW, the clock is currently accurate to within a fraction of a second per month, which I find to be almost unbelievable. When I began the calibration process, the clock was wildly fast, gaining over a minute per month.
DM15L, S/N 00548. DM42, SN: 00159.

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Walter
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Re: RTC Calibration program

Post by Walter » Thu Oct 24, 2019 2:00 pm

HPMike wrote:
Thu Oct 24, 2019 1:36 pm
Amazing ! Over a month has passed since I made the last calibration and there is no discernible change in the time setting when compared to my atomic watch.
Amazing! You own an atomic watch! :o May I ask you for a picture? Thanks in advance. 8-)
DM42 SN: 00041 --- Follower of Platon.

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

HPMike
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Re: RTC Calibration program

Post by HPMike » Thu Oct 24, 2019 2:16 pm

Walter wrote:
Thu Oct 24, 2019 2:00 pm
HPMike wrote:
Thu Oct 24, 2019 1:36 pm
Amazing ! Over a month has passed since I made the last calibration and there is no discernible change in the time setting when compared to my atomic watch.
Amazing! You own an atomic watch! :o May I ask you for a picture? Thanks in advance. 8-)
Sorry, it is top secret. ;)
DM15L, S/N 00548. DM42, SN: 00159.

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Walter
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Re: RTC Calibration program

Post by Walter » Thu Oct 24, 2019 4:25 pm

HPMike wrote:
Thu Oct 24, 2019 2:16 pm
Walter wrote:
Thu Oct 24, 2019 2:00 pm
HPMike wrote:
Thu Oct 24, 2019 1:36 pm
Amazing ! Over a month has passed since I made the last calibration and there is no discernible change in the time setting when compared to my atomic watch.
Amazing! You own an atomic watch! :o May I ask you for a picture? Thanks in advance. 8-)
Sorry, it is top secret. ;)
I understand - America first!
DM42 SN: 00041 --- Follower of Platon.

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

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H2X
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Re: RTC Calibration program

Post by H2X » Thu Oct 24, 2019 4:43 pm

HPMike wrote:
Thu Oct 24, 2019 2:16 pm
Walter wrote:
Thu Oct 24, 2019 2:00 pm
HPMike wrote:
Thu Oct 24, 2019 1:36 pm
Amazing ! Over a month has passed since I made the last calibration and there is no discernible change in the time setting when compared to my atomic watch.
Amazing! You own an atomic watch! :o May I ask you for a picture? Thanks in advance. 8-)
Sorry, it is top secret. ;)
Isn't it also quite small? :D
DM42 SN:00040 | Without deviation from the norm, progress is not possible - Frank Zappa

toml_12953
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Re: RTC Calibration program

Post by toml_12953 » Thu Oct 24, 2019 10:48 pm

H2X wrote:
Thu Oct 24, 2019 4:43 pm
HPMike wrote:
Thu Oct 24, 2019 2:16 pm
Walter wrote:
Thu Oct 24, 2019 2:00 pm

Amazing! You own an atomic watch! :o May I ask you for a picture? Thanks in advance. 8-)
Sorry, it is top secret. ;)
Isn't it also quite small? :D
The atomic watch itself is small but its reactor control rods are 2 meters long! :)
Tom L

My father was a man of the cloth. He was a tailor.

DM42 SN: 00025 (Beta)
SN: 00221 (Shipping)

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stefanoaz
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Re: RTC Calibration program

Post by stefanoaz » Mon Nov 11, 2019 9:51 pm

Thanks for this feature. I remember it was available in my otherwise unloved HP48, and I was hoping to see it in the DM42. -16.2 ppm dialed in. Always nice to have accurate time.
HP-41C, 48SX, DM-42 s/n 830

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