Does CORRECT and SETAF, RCLAF work on the DM41X ?

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EM41
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Does CORRECT and SETAF, RCLAF work on the DM41X ?

Post by EM41 »

One of the few things I didn't test till now was the clock correction.
Correct doesn't work, setaf and rclaf however seem to store and recall the correction factor.
Since the hardware from the DM41 is completely different from the HP41 I assume this doesn't work on purpose.
(would be nice to have it in the future because the clock isn't very accurate).

Erik
HP41C (2x), HP41CV, HP41CX, DM41X β, DM41X, DM42, HP11C, HP48G, HP97
rprosperi
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Re: Does CORRECT and SETAF, RCLAF work on the DM41X ?

Post by rprosperi »

Erik,

See section 3.6. RTC correction in the 41X manual. This is similar to the method used in the DM-1X/41L machines.
--bob p

DM42: β00071 & 00282, DM41X: β00071 & 00656, DM10L: 071/100
EM41
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Re: Does CORRECT and SETAF, RCLAF work on the DM41X ?

Post by EM41 »

Thanks, yes manuals sometimes they are useful :D
HP41C (2x), HP41CV, HP41CX, DM41X β, DM41X, DM42, HP11C, HP48G, HP97
Dave Britten
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Re: Does CORRECT and SETAF, RCLAF work on the DM41X ?

Post by Dave Britten »

I'm reading the RTC correction section of the manual, and not quite making sense of it. It says I need to calculate C based on a ppm correction, but doesn't say what this ppm correction represents, or how to measure it. And what effect does the sign of C have on the clock? Does a positive value speed up or slow down the clock? My DM41X is gaining a couple of seconds per day, and I'm trying to figure out how to calibrate it. Hopefully future firmware updates will use the native CORRECT/SETAF/RCLAF functions to handle this.
whuyse
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Re: Does CORRECT and SETAF, RCLAF work on the DM41X ?

Post by whuyse »

It's the same procedure as for the DM42, and there was a whole thread about it:
viewtopic.php?f=17&t=2007&start=90
Simply put: ppm is parts-per-million, so measure the time drift in seconds between two moments a million seconds apart ;-)
That's your ppm; use it to calculate C. To slow down the clock, use a negative value of C.
(I don't quite understand why we have to take the detour of calculating C, as in the settings menu the value of ppm is shown once you have provided a rtccalib.cfg file. So why not provide ppm directly, then?)

Cheers, Werner
42S #3249S01123
DM42 #00345
HPMike
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Re: Does CORRECT and SETAF, RCLAF work on the DM41X ?

Post by HPMike »

whuyse wrote:
Wed Oct 21, 2020 5:41 pm
I don't quite understand why we have to take the detour of calculating C, as in the settings menu the value of ppm is shown once you have provided a rtccalib.cfg file. So why not provide ppm directly, then?

Cheers, Werner
Perhaps it has something to do with the factor C read from the RTCCALIB.CFG file having to be an integer ?
DM15L, S/N 00548. DM42, SN: 00159. DM41X, SN: 00973.
firai
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Re: Does CORRECT and SETAF, RCLAF work on the DM41X ?

Post by firai »

whuyse wrote:
Wed Oct 21, 2020 5:41 pm
It's the same procedure as for the DM42, and there was a whole thread about it:
viewtopic.php?f=17&t=2007&start=90
Simply put: ppm is parts-per-million, so measure the time drift in seconds between two moments a million seconds apart ;-)
That's your ppm; use it to calculate C. To slow down the clock, use a negative value of C.
(I don't quite understand why we have to take the detour of calculating C, as in the settings menu the value of ppm is shown once you have provided a rtccalib.cfg file. So why not provide ppm directly, then?)

Cheers, Werner
I think that's the format that the STM chip takes to calibrate the clock: https://www.st.com/resource/en/applicat ... ronics.pdf. Since the calibration can only be done in integer increments of C (varying from increment of ≈0.95275 ppm at C=-511 to increment of to increment of ≈0.95368 ppm at C=1 to ≈0.95461 ppm at C=+512 per STM documentation), having an input in ppm could introduce round-off errors and set unrealistic expectations?
Sam
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