Solved: Logic for 365 days for sunset and sunrise

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salmanma6 wrote:
So you all recommend me to use gps module?
I do not.

Reasons : contrast, the journey, the more ways the merrier wink

Alternates :

  • GNSS instead of GPS

Why (though not applicable for your application) : http://gpsworld.com/australia-drifts-away-from-gnss-measurements/

Some differential GNSS data that arrives from land-based transmitters may have local daylight saving time data.

Differential GNSS data is used by farmers due to GNSS-aided row cultivation.

This increases the degree of difficulty; land-based long wave radio time may be preferred if it's available where you are at.

  • cellular modem

Reason :

U.S. Department of Commerce

National Institute of Standards and Technology (NIST)

Time and Frequency Services

Manufacturers of Time and Frequency Receivers

https://www.nist.gov/pml/time-and-frequency-division/time-services/manufacturers-time-and-frequency-receivers

....

CDMA Disciplined Oscillators

...

Is daylight saving time data (direct or indirect) in the time data from a cellular modem?

 


Long wave time transmitters :

http://www.c-max-time.com/tech/transmitter.php

 

http://store.oregonscientific.com/us/desktop-radio-controlled-alarm-clock-yellow-rm938.html (WWVB, MSF, DCF)

 

"Dare to be naïve." - Buckminster Fuller

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I am a little sceptical about the transmitter coverage. My experience with home made MSF receivers is that the signal is not that good.
Can they really receive MSF in Greenland?
Can you really receive WWF over most of the US?
.
All the same, the £10 MSF radio controlled clock on the wall in front of me works very well.
.
I suspect that time data from FM radio is the most reliable method if you are travelling in a car. And you probably get FM stations in most of the world. Or mobile phone signals (except in Wormshill)
.
David.

Last Edited: Sat. Mar 18, 2017 - 07:41 PM
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Inside a building
No limit for budget
-7 segment displays
No I didn't calculate
Just need precise timing

Salman

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david.prentice wrote:
Can you really receive WWF over most of the US?
For WWVB night time is best and do have to be aware of the better locations for one's WWVB receiver antenna.

https://www.nist.gov/pml/time-and-frequency-division/popular-links/help-radio-controlled-clocks#where

 

Hawaiʻi WWVH is the (are there others?) short wave time transmitter for the Pacific Ocean.

https://www.nist.gov/pml/time-and-frequency-division/time-services/wwv-and-wwvh-digital-time-code-and-broadcast-format

 

"Dare to be naïve." - Buckminster Fuller

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There IS merit to carrying more computational digits than you can display. For, it is in those undisplayed "digits" where error  is managed. 

 

I am beginning to think that GPS may be a useful solution. The receivers output serial strings containing location in latitude and longitude as well as current time. IF the user location is going to be relatively fixed (say, within 100km radius), a fixed time offset can be applied, though daylight  saving time may be a bit problematic (if it is used in the user location) because that often does not change on a fixed calendar date, but often on the weekend closest to that date. 

 

GPS is quite precise, long term, because it is constantly corrected to the national time standards. The whole GPS system, however, MAY not have a lifetime as long as the user's life. New systems are being designed, now, and the first sats will go up within the next few years. Compatibility, at this point, is uncertain. All of this taken into account, GPS may be the simplest way to get long-term stable time for salmanma6 with the understanding that there is a real possibility that it may not continue to work during the full extent of his life. After all, nothing is "permanent"!

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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No limit to budget - pay someone who knows what they're doing then! Problem solved.

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salmanma6 wrote:

So you all recommend me to use gps module?//Since derived from atomic clocks

another thing ...do this atomic clocks have some errors..>?i.e...gain or loss time?

 

Time, as Einstein put it is relative to the observer.  There is no Absolute time.  Where you are depends on the time observed.  Atomic clocks are simply accurate enough to show the difference gravity affects time.   These clocks when calibrated in stable environments are accurate to parts per billion.  Which works out to seconds over billions  if not trillions of years.  The structures these clocks are made of probably will not last that long.

 

Everything we use is an average called a mean.  The earth wobbles a bit.  The moon wobbles a lot.  The difference between the mean average and the actual measurement is not so much an error as it is a correction.  GPS and the network sync clocks have the provisions to leap and drop seconds.

 

Once again sunrise sunset is related to Sidereal time 23 hours, 56 minutes, 4.0916 seconds.   This is the time it takes the earth to rotate 360 degrees.  It takes 365.2425 of these rotations to complete a year.  There is a point in the sky.  It marks the day the sun rises on the first day of spring in the northern Hemisphere.  This point is called "The first point of Ares."  Currently this point is ether in the constellation Pieces or Aquarius depending on which star maps are used. By chance this occurrence happens to be this week.  Over the last 6000+ years or more Humans have lined up stones to mark this event.  They found errors.

 

It was quickly discovered from these stones that the earth wobbles a bit on it's axis.  It takes 25,920 years for this wobble to complete one revolution.  During the time of the Egyptian pharos say 3000 BCE the sun rose in the constellation Ares on the first day of spring.   By the time of Caesar and Cleopatra in 50 or 40 BCE the leap year was introduced.  At the start of the Renaissance The 400 year rule was added as the calender was out by a week and a half.  When the US of A was founded in the late 18th century the western calendar was out over two weeks.  Russia did not adopt the modern calendar until 1917,   The Russian church still uses the Roman calendar of say 42 BCE.  

 

You are going to have errors!  There is nothing one can do about it.  These errors are what science is all about.  For much of Human history it was though that the sun moved and the earth remained still.  One of Cleopatra's Cousins came up with improvements to a system that gives it the name Ptolemy.  It is all based on circles that turn inside circles.  It took thousands of years observation to work out.  The Ptolemaic system is about 99.99 percent accurate. It was in use 1000s of years.  Still it was not good enough for the people in the middle ages that felt that .001 percent error was wrong.   This lead to the discovery of modern mathematics that were able to show that the earth moves and the sun stays still.  The accuracy went up to say 99.999999 percent.   There were still errors so that Einstein guy I keep quoting figured out that Gravity was affecting time.   That the sun is not a fixed point.  It moves through the galactic spiral, up and down through the galactic plain like a merry-go-round horse.

 

In other parts of the world known as Asia, there was a feeling that time is an illusion.  This is more philosophy than science.  Yet the results start looking the same.  Gravity connects everything in the visible sky to the closest thing you can see.  Another set of rules affect the things you can not see, these are what we call quantum physics.  Quantum physics is in effect one really big error.  It says you can not know when or where anything is.  This brings us to the maths that rules the modern world.  Probability and statistics.  This tells you what the error is going to be. Most of the time.

 

So like the other said, you make a table.  Then you take the mean averages at the realistic accuracy you want and apply them to your result.  The rest is betting and gambling (like the stock market.)  Some things like the sun rising tomorrow are a pretty sure bet.  Others such as when your next meal will be is much more of a chance.

 

There is another way to correct for these errors.  This is called the phase locked loop.  An oscillator, such as a clock is made to run a bit fast.  Every so often it is synced.  Stopped to start over.  This keeps it in phase.  In clocks this is called the escapement.  The sound is the familiar tick of a timekeeper.  In the human body the natural cycle called the circadian rhythm  is about 25 hours.  The reset signal is the rising of the sun. (or the sudden exposure to artificial light.)  A single photon on the skin can cause this reset.   In a television or display device this impulse happens on every frame.  There are countless more examples.

 

One of my favorite clocks is the https://en.wikipedia.org/wiki/Strasbourg_astronomical_clock by Jean-Baptiste Schwilgué.  He made an analog computer that ins incredibly accurate to account for much of the observed errors in his own time. It was

not superseded  in accuracy until the Digital computers of the 1960s.  Each of the cams in the stack represents  errors from the input system.  Here is a photo from the wikipedia page:

 

 

There is a gear in this clock that turns once every 25,920 years!  Now that guy was an optimist!

 

 

 

 

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Ross McKenzie ValuSoft Melbourne Australia

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salmanma6 wrote:
Inside a building No limit for budget -7 segment displays No I didn't calculate Just need precise timing

 

Other factors: power use, mains or battery?

 

Practical options to get an absolute time reference for the hobbyist:

 

1. GPS (GNSS etc) receiver

 

Easy to interface

Generally available

Requires antenna near window

 

http://www.ebay.com/bhp/gps-rece...

 

 

2. Radio (MSF/DCF/WWF etc)

 

Requires decoding

Signal depends on location

DIY or specialist supplier (or hack from off the shelf radio clock)

 

http://www.pvelectronics.co.uk/i...

 

3. NTP (or other time server)

 

Wifi modules easily available

Requires internet access (ethernet or wifi)

 

 

There isn't an obvious no-brainer, all 3 options have pros and cons.

Bob.

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On inverter battery

Salman

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This thread was worth it simply for jporter's posts! They should get some kind of award.

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GPS gives UTC, without any offset.

 

It is important to recognize that GPS DOES NOT work well in all locations. Inside buildings, for example. Especially lower floors of multi-story buildings or structures with metal roofs. Sometimes, you can put the GPS with its antenna in a window  and have it  work, depending on what else is close by.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Quite honestly,  you can rely on occasional synchronisation.   Like a radio clock.   Most of the time it runs on its crystal.   It checks the WWV, MSF, DCF77, ... radio signal at regular intervals.   And corrects the time if necessary.

 

This means that your device could work ok in a car or as a handheld.    It is fairly likely to get a good signal at least once a day.

If it is on a fixed wall,   it might get a good signal at night time even if the site is in a poor reception area.

 

Likewise,   a phone, GPS,  FM radio, TV, ... all provide accurate time data.    You only need occasional access to make any correction.    How often do you correct your wristwatch?   Every few months?   Once a year?

 

We are all guessing that the purpose of this exercise is to give accurate prayer times.    10 minute accuracy would be good enough for most people.

 

David.

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You are right David....accurate prayer timing
That is why I was saying...I want best precision
I.e...less amount of error
Setup will be on the wall
Inside a building
So reading all of the posts I think I need to use GPS module and I'll connect it to antenna on terrace
So shall I proceed?

Salman

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salmanma6 wrote:
Setup will be on the wall Inside a building So reading all of the posts I think I need to use GPS module and I'll connect it to antenna on terrace So shall I proceed?

 

GPS is certainly a good way to calibrate, and re-sync, but you may not want to depend 100% on GPS.

I'd use a TCXO and run GPS in parallel, so GPS locks raw time, (when available) and TCXO runs over any dropout.

 

You may find then that a modest local battery can allow you to move the unit to where it can get GPS, and then replace on wall. (ie save a cable)

(that also would run thru any local power fail - you do not need to power the 7 segments during oscillator keep)

 

If you also used the 1pps, it will not take long to get a calibrate value on the ppm/ppb of the TCXO.

(capture of 1pps on a 16MHz Oscillator is 62.5ppb-second product, just 10s gets you under 10ppb)

 

You may find, with a good TCXO and calibrate design, the GPS is more optional, and only needed at initial install/setup.

 

Antenna leads cannot be too long, so you could need to mount the whole GPS module on terrace (or window sill), and run the serial info, (& 1pps) using RS232 buffers.

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Occasional synchronization is a useful tool. And it can, if properly designed, reduce power consumption. Since the maximum typical error with a 32.768KHz watch crystal is around 30ppm (a few seconds per day), even recalibrating once a day should do well. For this application, one might think of the process as follows:

 

1. Count seconds from some arbitrary "reference time" using the crystal clock. Derive minutes, hours, day, month, and year, from this.

 

2. Once a day, or so, compare the derived time against the time from the GPS. If it is fast, subtract the appropriate seconds from your local clock. If slow, add.

 

It ends up being a relatively simple machine, and relatively easy, in the grand scheme of things, for a beginner to work into. Don't expect to find a project you can copy on the internet. YOU are going to have to learn at least some programming and you are going to have to do most of what is needed, for yourself. With help, maybe lots of help, certainly. But just don't expect to have others work everything out for you! Where to start? Blinking LED is the top choice.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Consider this approach....
1)
I will directly draw values from string returned by GPS
And will display
2) Reference time from microcontroller ..as ka7ehk stated...daily for onetime ..GPS returned time and ref time is compared ..if less add.....if more substract
3) what who-me stated using tcxo

I think 1 is best as..no need to write extra code just repeat the steps
While(1)
{
Derive from GPS code
Display code
}
Is this valid
Need your opinion

Salman

Last Edited: Mon. Mar 20, 2017 - 06:03 PM
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(1) works IF you have good GPS reception and you have plenty of power. Then, again, you would have to have plenty of power to use an LED display. Not a good fit for batteries!

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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How 2nd approach ..achieves the drawback?

Salman

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No particular drawback with #2. It just takes a bit more programming. You might want to include a software-controlled power switch for the GPS if you want to reduce power consumption to a minimum. This switch can be as simple as a transistor (FET).

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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salmanma6 wrote:
Consider this approach.... 1) I will directly draw values from string returned by GPS And will display 2) Reference time from microcontroller ..as ka7ehk stated...daily for onetime ..GPS returned time and ref time is compared ..if less add.....if more substract 3) what who-me stated using tcxo I think 1 is best as..no need to write extra code just repeat the steps While(1) { Derive from GPS code Display code } Is this valid Need your opinion

 

These are not mutually exclusive, and you can design the system with all 3.

 

Including a TCXO is a no-brainer, as that gives a good timebase axis.

 

Then, you can use GPS to set the time, when available, and always run the timers from the TXCO.

If you want to calibrate the local time base, from the GPS, that is also possible, but I'd suggest including the 1pps signal, with the Serial info, to give you more choices there.

 

The best calibrate schemes would run a fractional-correcting counter, and measure the TCXO offset.

That tolerates the longest GPS down time, and could even be ok with a one-time calibrate. (RTCs have some examples of digital trimming, google is your friend)

 

salmanma6 wrote:
No limit for budget

 

Of course, if that really was an accurate statement, then you can get one of these, ext stock at Digikey

 

http://www.digikey.com/product-d...

 

AOCJY6-10.000MHZ-1     OSC OCXO 10.000MHZ SINE WAVE PC    US$1,798.07000  Sine Wave    11.4 V ~ 12.6 V    ±0.1ppb    -20°C ~ 70°C    
Through Hole    6-DIP (1.260", 32.00mm), 5 Leads    2.008" L x 1.614" W (51.00mm x 41.00mm)    0.984" (25.00mm)

 

 

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I use http://www.digikey.co.uk/product... as a balance between price and performance. Accuracy is probably a few seconds per month, so syncing with GPS every 24 hours would be fine. With a battery backup, it is resilient to power outages.

 

There are some Arduino libraries that can be used with DS3231, which is also nice.

Bob.

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Who-me wrote:
salmanma6 wrote: i dont know the maximum precision that one can achieve...so i said best precision

So you get a rubidium standard.

Second hand will only set you back about USD200

A new one probably a couple of thousand.

That will be about the best accuracy that a hobbyist can afford.

 

Look where this trhead is going.

OP started with a table of 256 values which he deemed to big.

I suggested a neat suggestion of a lookup table and linear interpolation, but that was rejected.

 

This tread has 1074 views now.

So I want to suggest to the OP to read this whole thread 1074 times to give him some idea about the amont of effort that is wasted because wanted to save 5 minutes of his own time by not taking some time to phrase his questions carefully.

Paul van der Hoeven.
Bunch of old projects with AVR's:
http://www.hoevendesign.com

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Paulvdh...I didn't reject your idea..that was solution for logic.but I'm still unclear about that..but when I started discussing little more ,concern about accurate time...made me write these many posts..
Many of posts were very useful
I thank all of them
I seriously apologize for that
Okay I'm done what to do with time

Salman

Last Edited: Tue. Mar 21, 2017 - 02:06 PM
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Can u a bit more clear.? I don't get about the table
Just give a sample code

Salman

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Precalculated lookup table...I need more clarity
Just give me sample code

Salman

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salmanma6 wrote:
Just give me sample code

As well as doing all your googling for you?

 

In one of your other threads you asked, "Can a computer science graduate get job in electronic companies?"

 

http://www.avrfreaks.net/forum/e...

 

And, in the "accepted solution", I said:

 

show that you have an interest in, aptitude for, and ability to learn about electronics

 

That means getting down and working on your own initiative - not expecting everything to be "spoon-fed" to you.

 

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Surely this is obvious? You Google the sunrise/set equation you need. You put it into Excel. You have it generate a table of values for every day of the year. You output the result to Comma Separated Values. Excel has now written the main C source data you need to populate your table. After that it's just a question of picking out the right values and displaying them as required.

 

I doubt anyone here is going to do all that for you. It's up to you to take the ideas/leads made here and then research and implement them yourself - this is what professional engineers get paid for!

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Sir ,I'm not asking you to Google rather answer if you know and can summarise about that...
Tell me what type of questions should i ask ?

Salman

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I have a sheet of timings for every day of every month... I don't wanna calculate
Just how to store those and retrieve according to day and month
My code was for someday,some month, I will manipulate the variables of sunset and sunrise
But that will end up with big code
That's y I posted this in general programming

Salman

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The code really is not that big. Consider that there are 86,400 seconds per day. That won't quite fit a 16 bit integer (65535) but 18 hours will. Since it is never that long between sunrise and sunset except in the far north or south,  YOU should be OK. Just reckon your sunrise and sunset as seconds after 4AM. THAT will fit into an unsigned 16-bit integer. So, you have 2 16-bit integers per day. For 365 days per year, your table only takes 1460 bytes and that can be put into ROM (FLASH). The code will NOT be "big"! 

 

It will probably take about that much flash just do decode GGA strings from a GPS. It will take a some to display your values. Thats about it. Again, NOT BIG CODE! In fact, almost trivial.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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In post#2 clawson already outlined one way of doing this.

Another way, for each day of the year store the sunrise and sunset times:

typedef struct {
    uint8_t hour;
    uint8_t minute;
    uint8_t second;
} time_of_day;

time_of_day sunrise_time[366];  // Allow for leap years
time_of_day sunset_time[366];   // Allow for leap years

I did a quick program on a board I had handy and after initialization of the arrays, I could display the data on an lcd as:

            sprintf(text_buffer,"%d:%d:%d   ", sunrise_time[day_tracker].hour, sunrise_time[day_tracker].minute, sunrise_time[day_tracker].second);
	    spi_lcd_setCursor(40,32);   // Start display at x=40,y=32 (pixels from upper left of display)
            spi_lcd_print(text_buffer);
            sprintf(text_buffer,"%d:%d:%d   ", sunset_time[day_tracker].hour, sunset_time[day_tracker].minute, sunset_time[day_tracker].second);
            spi_lcd_setCursor(40,64);   // Start display at x=40,y=64 (pixels from upper left of display)
            spi_lcd_print(text_buffer);
            day_tracker++;
            if (day_tracker >365) {day_tracker = 0; }

where the variables are declared as uint16_t day_tracker;  and char text_buffer[15];.

 

This whole program takes about 5K of flash and 2286 bytes of ram (not including stack). Ram could be saved if the sunrise and sunset arrays were placed in flash.

(The flash in this case contains a font table, and initialization of other peripherals on the board that would not be needed in dedicated environment.)

 

So "But that will end up with big code" is not necessarily true.

 

EDIT: (confession) Sorry guys, but for this I did not sit down with pencil and paper and think about what I wanted to do... I just typed it in with no (real) thought process!

Edit2: typo

Last Edited: Tue. Mar 21, 2017 - 05:22 PM
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ka7ehk wrote:
The code really is not that big. Consider that there are 86,400 seconds per day. That won't quite fit a 16 bit integer (65535) but 18 hours will.

Or work in minutes - as Cliff did right back in #2 

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as Cliff did right back in #2

Just to point out folks that somewhere in this interminable thread a further suggestion was made to not store complete (16 bit) rise/set times in minutes for each day but that because the variation between one day and the next is small to just store the per day deltas. That should let you store each (rise/set) in 366 bytes (and the datum value that you start with to apply the deltas too).

 

I actually preferred that as an idea over my #2.

 

BTW if this is about when to get out the prayer mat does God actually care if you are .00003 seconds late? (or even a minute one way or the other?) so all the talk of TXCO's or rubidium clocks or even GPS may just be a fraction of over-kill / over engineering perhaps?

 

I know that an infinite budget has been specified but I'm a Northerner and therefore, by definition as tight as tuppence!

 

I do wonder if Russell's suggestion in #78 may have been a little over-looked too? That seems to do it by calculation/formulae rather than look up table but is still "tight" code. (and what's more it is not fixed values but even calculates according to given Lat/Lon)

 

Oh and if it is about Islamic prayer (or rather the avoidance of during sunrise/sunset) you don't actually need an infinite budget to collect something suitable here... http://www.ebay.com/bhp/azan-clock

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If nearest minute is sufficient, then, yes, use minutes since midnight. Code to convert minutes-since-midnight to hour and minute is quite compact. Still two 16-bit integer values  per day for 1460 flash bytes.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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My project also consists of fasting times and other islamic times for evry day
I asked for sun set and sunrise so that I can apply the same logic to all .
Precise time is needed .Yes needed.

Attachment(s): 

Salman

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Attachment is unclear..
Ignore

Salman

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A part from all these options ...can I directly use rtc?
Seriously I need to start!..need help

Salman

Last Edited: Thu. Mar 23, 2017 - 06:26 PM
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salmanma6 wrote:
Seriously I need to start!..need help

 

Salman,

 

You need to start? Well is anyone here preventing you from starting? You sound like you expect someone else to deliver the whole solution to you via this website. It isn't going to happen my friend. We have given you lots of suggestions for your clock questions, but please do not expect us to solve your very, very specific fasting and prayer timing requirements. As others have indicated this "problem" has been already solved commercially elsewhere. Ebay has many such clocks. Why must you reinvent that wheel?

 

Stop begging... start doing... please.

Ross McKenzie ValuSoft Melbourne Australia

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well i didnt ask solution for everything i stated
i just asked whether i can use rtc or not...
u are misunderstanding the situation

Salman

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salmanma6 wrote:

I asked for sun set and sunrise so that I can apply the same logic to all .
.

here i mean that if i know about retrieving sunset and sunrise..i can do othrs on my own.
thats y i asked about sunrise and sunset problem
now i got that too

Salman

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salmanma6 wrote:
i just asked whether i can use rtc or not...

Of course - you can use almost anything.

There have been TCXO RTCs mentioned above you could use, to get single-digit ppm precisions.

Unless you are power-paranoid (and it seems not, with LEDs), a MHz TCXO is easier to GPS calibrate, and those are just over $1, for 0.5ppm

So there is really no excuse to not use one, in a project where you desire precision.

 

That 0.5ppm can be further improved, if you can be bothered, with either one-off calibrate, or a regular GPS re-trim using the 1pps.

 

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Solved the thread
Thanks everyone
Very useful!thanks again
Sorry for the inconvenience I created

Salman

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