It has temperature and age compensation of the oscillator (This makes it a TCXO), this is possible because the crystal is build into the chip. PCF8563: Another simple RTC chip with one alarm (Can be used to bring a processor out of sleep), but only a single power input (Combining battery and normal power must be done externally), no battery charging supported.ĭS3231: This chip is more advanced and also have two alarms (Can be used to bring a processor out of sleep). In the Arduino world this translates to:Ģ) Reset, Arduino is reset when connected to a PCģ) Workload, Arduino is doing too much and can not spare the resources to keep precise time.Ĥ) Blocking tasks, the program needs to disable/ignore interrupts for some time.ĥ) You Arduino has a ceramic resonator and it varies too muchĦ) You Arduino uses a internal RC oscillator, this is worse than a ceramic resonator.ħ) High precision clock, a advanced RTC chip may have special circuit to make the oscillator more stable.ĭS1302: This is a simple RTC chip with the crystal, input for battery and normal power, option to charge battery, date and time registers and a few bytes spare ram. With a battery, low power consumption and independent operation it is perfect for keeping time when a device has other stuff to do and in some cases it may improve the precision. Because the chip is battery backed it will often have a small amount of extra non volatile ram that can be used by a microprocessor. The chip will count seconds and organise the result in seconds, minutes, hours, days, months and years. Divide 15 times with two and you got 1 pulse every second (Divide by two is the simplest divider to make).It is fairly low, this means low power consumption.it is used in many different types of electronic clocks, there are two reasons for the frequency: The 32768Hz crystal is a typical watch crystal, i.e. Lets first look at what a RTC ( Real Time Clock) is and in what applications a RTC is necessary.Ī typical RTC consist of a chip, a battery and a tiny 32768Hz crystal. Here are some of the values used to specify time precision with a conversion between them. The data are a rough specification for that type of technology, there will be both better and worse devices around.
The above table shows some of the different technologies used to get a stable frequency or time. ProMicro simulating Arduino Leonardo (Mega32U4) How to measure amount of adjustment to applyĬlock with seconds, minutes, hours, date, month, year Here I will look at how precise the Arduino is and how to get the best possible time precision. I often see people want a RTC connected to their Arduino to get more precise time, but that is not always necessary. Making Arduino timing more precise Making Arduino timing more precise
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