3 HOUR 18 MINUTE TIMER CODE

This increase in speed is thought to be due to various factors, including the complex motion of its molten core, oceans, and atmosphere, the effect of celestial bodies such as the Moon, and possibly climate change, which is causing the ice at Earth's poles to melt.

Because of that trend, engineers worldwide are discussing a 'negative leap second' and other possible timekeeping measures. On June 29, 2022, Earth's spin was completed in 1.59 milliseconds under 24 hours, setting a new record. Scientists reported that in 2020 Earth had started spinning faster, after consistently spinning slower than 86,400 seconds per day in the decades before. Analysis of historical astronomical records shows a slowing trend the length of a day increased about 2.3 milliseconds per century since the 8th century BCE. Atomic clocks show that the modern day is longer by about 1.7 milliseconds than a century ago, slowly increasing the rate at which UTC is adjusted by leap seconds. This is due to the tidal effects the Moon has on Earth's rotation. Earth's rotation is slowing slightly with time thus, a day was shorter in the past. The South Pole is the other point where Earth's axis of rotation intersects its surface, in Antarctica.Įarth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes and 4 seconds with respect to other distant stars ( see below). This point is distinct from Earth's North Magnetic Pole. The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where Earth's axis of rotation meets its surface. As viewed from the northern polar star Polaris, Earth turns counterclockwise. Earth rotates eastward, in prograde motion.

The duration of a 'second' is subjected to caution.Playing with TMR1H, TMR1L and nb may be required.Earth's rotation imaged by Deep Space Climate Observatory, showing axis tiltĮarth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. problem with modulo and pic.do not use % INTCONbits.GIEH=1 // autorise interuptions PIE1bits.TMR1IE=1 //enable interupt on timer1 INTCONbits.TMR0IE=0 // interuption activation on timer0 (0=no active) RCONbits.IPEN=1 // Interruption prioritaires PIR1bits.TMR1IF=0 //erase interruption flag if set INTCONbits.TMR0IF=0 //erase interruption flap if set IPR1bits.TMR1IP=1 // high priority interuption timer1 INTCON2bits.TMR0IP=0 // low priority interuption timer0 TMR1H=0x00 //setting timer1 : high bit first T1CONbits.T1CKPS1=1 //prescaler 11 -> 8-prescaled T1CONbits.RD16=1 //timer1 is a 16-bit timer OSCCON=0x7D //Internal oscillator, 8Mhz Void interrupt low_priority low_isr (void) PIR1bits.TMR1IF=0 //erase interrupt flag of TIMER1 TMR1H=0 // Values calculated for 1 second delay with 4MHz crystal If(PIR1bits.TMR1IF) //interrupt flag of TIMER1

3 HOUR 18 MINUTE TIMER CODE

Here is a code compiled by XC8 and tested with the simulator of MPLAB X. So a for loop is needed to count a second. It is not the case of timer1, but timer1 is a 8-prescaled 16-bit timer.

Unfortunately, the timer0 is switched off by the SLEEP() command. Since nothing is done in the while(1) loop, i wanted to use the SLEEP() command to spare some energy. Whatever is happening, as the overflow of the timer occurs, the interrupt flag is raised and the interruption function is executed within a few cycles. To overcome this, using interrupts is the way to go. So if long computations are performed in that loop, the precision will decrease. Ī source of uncertainty is that the overflow of the timer is checked once in the while() loop. And another one for minutes, and another one for hours, as suggested by. The solution is to add a for loop to count the seconds. So a 256-prescaled 16-bit timer is sufficient to count a second.

3 hour 18 minute timer