1 day delay

velja · Joined: 17 Aug 2015 Posts: 4

Hi,
I make weather station with atmega328 on 16MHz. I need for rain gauge period of 1 day. I can count impulse from rain gauge, accumulate it, but after 1 day I have to reset that value (mm/day rain fall). I use timer1 on interrupt for measuring period for wind speed sensor so I can't use it for making time base. How to solve this problem?

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

In my web severs in the blog section I have created a real time clock
using the CPU clock I increment a variable during this interrupt
the variable is there to get NTP time each 24hours you could use
this for your purpose.
Regards Paul

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

With Arduino Uno you can't use the internal clock system because the M328 use PB6 and PB7 with the external 16MHz crystal so impossible to use a 32Khz crystal

but you can use an external I2C RTC as DS3231 or other softclock then you can use varWord= Sysday()

JP Wink

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Hello Jp
I use the 16Mhz CPU clock and if you measure the frequency of the clock
I have found it to be ok for 24hour periods I then updated via NTP
Regards Paul

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

Hi paul,
Right ! Embarassed

I didn't look at your work before http://www.mcselec.com/index2.php?option=com_forum&Itemid=59&page=viewtopic&t=12358&postdays=0&postorder=asc&start=0
Nice indeed !
but velja use a M328, is it possible to use Wiznet W5100 with a M328 and add all components of weather station ? maybe... I did a lot of programs on M32.

JP
Wink

velja · Joined: 17 Aug 2015 Posts: 4

Well, it's not essential to be 24 hours strictly. About external RTC, I have module with DS1307 but it fit on 5V system which is not mine. I use 3,3V, but it is important to use less components as it is possible with low power consumption as it is solar powering device. The one day period is on second place.

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Hello velja
It does not matter what voltage or crystal you just change the numbers
Have a look at this code http://www.mcselec.com/index2.php?option=com_forum&Itemid=59&page=viewtopic&t=10604&highlight=using+cpu+clock
you only need the interrupt to increment a variable
every second and to check if its 24hours worth of seconds
in your main program if it is reset to zero and do the task.
Note you do not need the date time library or lcd only the interrupt.
Regards Paul

O-Family · Joined: 23 May 2010 Posts: 320 Location: Japan

If Timer0 or Timer2 is not used, 1 second can be created even with 8bit timer.
And it is possible to count it 24 hours.