On 1/19/14 4:10 PM, Tom Van Baak wrote:
So, do you run the whole thing off 12V (which is what I'm going to do)
and a float charged battery OR do you do something clever like detect
when power is failing and save it in NV storage, then when you come back
up, you send a bunch of clock ticks real fast to catch up.
Use a high-res Arduino web cam facing the wall of clocks and write OHR (Optical
clock-Hand Recognition) code. That way its a single robust solution for setting
it the first time, restarting it on power failure, resyncing after replacing a
failed clock, or self-correcting after any mechanical glitch. You can also use
the same video feed to show off the project live on the JPL web site.
No, a low res cam with a robotic arm that moves it in front of each
clock in turn..
That is what is called "scope creep"..
I'll be happy if I get ONE clock running reasonably..
I've got the Arduino code running that does the EOT, once a second (but
using delay(1000) not the ISR), calculates the rate estimate, and
accepts a sync command over the (emulated) serial port to set the time
and date.
Curse the folks who develop "processing" because the current version
supports Mac OSX 10.7 and later, but not 10.6, which I am using, so I
don't have the nifty "click here to sync the Arduino" routine that's
provided as an example with the Arduino Time library.
Next I have to integrate the code I've got now with the other sketch
that does the ISR off the hardware timer.
---
#include <Time.h>
// Solar clock to drive mechanical mechanism
// Jim Lux, 19 Jan 2014
#include <math.h>
#define TIME_MSG_LEN 11 // time sync to PC is HEADER followed by Unix
time_t as ten ASCII digits
#define TIME_HEADER 'T' // Header tag for serial time sync message
#define TIME_REQUEST 7 // ASCII bell character requests a time sync
message
// T1262347200 - sample sync message
const double refclk=31376.6; //16 MHz/510?
const int clkpin1=6; // pins going to external clock
const int clkpin2= 7;
int dd, hh; //current day and hour
boolean UpdateClockFlag; // tells loop() that an interrupt has occurred
void setup(){
pinMode(clkpin1,INPUT); // set pins as inputs High Z for now.
pinMode(clkpin2,INPUT);
Serial.begin(9600);
delay(1000);
UpdateClockFlag = false;
}
void loop(){
int DOY;
double e1,e2;
double secsperday,ratedelta;
time_t t;
t = now(); // get the time
if(Serial.available() )
{
processSyncMessage();
}
delay(1000); // hack, til we get ISR timer running
UpdateClockFlag = true; // hack
if (UpdateClockFlag) {
if(timeStatus() == timeNotSet)
Serial.println("waiting for sync message");
else {
DOY = DayWeekNumber(year(),month(),day(),weekday());
hh = hour();
e1 = eot(DOY,hh); // EOT in minutes
e2 = eot(DOY,hh+1);
secsperday = (e2-e1)*1440;
ratedelta = secsperday*1.E6/86400; //ppm for now,
// but we'll change to
divisor later
Serial.print(ratedelta); Serial.print(" ");
digitalClockDisplay();
// code in here to update interrupt divisor, etc.
};
UpdateClockFlag = false;
}
}
// equation of time code from Tom Van Baak
//http://www.leapsecond.com/tools/eot1.c
double eot(int day,int hour){
double Pi = 4 * atan(1);
double y = (2 * Pi / 365.0) * (day - 1 + (hour - 12) / 24.0);
double eqtime = 229.18 *
( 0.000075
+ 0.001868 * cos(y)
- 0.032077 * sin(y)
- 0.014615 * cos(2*y)
- 0.040849 * sin(2*y)
);
return(eqtime);
}
void processSyncMessage() {
// if time sync available from serial port, update time and return true
while(Serial.available() >= TIME_MSG_LEN ){ // time message
consists of header & 10 ASCII digits
char c = Serial.read() ;
Serial.print(c);
if( c == TIME_HEADER ) {
time_t pctime = 0;
for(int i=0; i < TIME_MSG_LEN -1; i++){
c = Serial.read();
if( c >= '0' && c <= '9'){
pctime = (10 * pctime) + (c - '0') ; // convert digits to a
number
}
}
setTime(pctime); // Sync Arduino clock to the time received on
the serial port
}
}
}
void digitalClockDisplay(){
// digital clock display of the time
Serial.print(hour());
printDigits(minute());
printDigits(second());
Serial.print(" ");
Serial.print(day());
Serial.print(" ");
Serial.print(month());
Serial.print(" ");
Serial.print(year());
Serial.println();
}
void printDigits(int digits){
// utility function for digital clock display: prints preceding colon
and leading 0
Serial.print(":");
if(digits < 10)
Serial.print('0');
Serial.print(digits);
}
int DayWeekNumber(unsigned int y, unsigned int m, unsigned int d,
unsigned int w){
int days[]={0,31,59,90,120,151,181,212,243,273,304,334}; // Number
of days at the beginning of the month in a not leap year.
//Start to calculate the number of day
int DOY;
if (m==1 || m==2){
DOY = days[(m-1)]+d; //for any type of year, it
calculate the number of days for January or february
} // Now, try to calculate for the other months
else if ((y % 4 == 0 && y % 100 != 0) || y % 400 == 0){ //those are
the conditions to have a leap year
DOY = days[(m-1)]+d+1; // if leap year, calculate in the same
way but increasing one day
}
else { //if not a leap year, calculate
in the normal way, such as January or February
DOY = days[(m-1)]+d;
}
return DOY;
// Now start to calculate Week number
// if (w==0){
// WN = (DOY-7+10)/7; //if it is sunday (time library
returns 0)
// }
// else{
// WN = (DOY-w+10)/7; // for the other days of week
// }
}
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