Contents
What are real time clocks in microcontrollers?
This article is the third of a series on microcontroller timers. The first article describes the major features of most types of timers and covers periodic timers, and the second covers pulse width modulation MCU timers. Real-time clocks (RTC) are timers dedicated to maintaining a one-second timebase.
How to use PIC microcontroller timers as an interrupt?
Set GIE to 1 to enable global interrupts. Set TMR0IE to 1 to enable timer0 interrupts. Now an overflow of timer0 will set TMR0IF bit, and cause an interrupt. You will need to test TMR0IF to verify the cause of interrupt and reset it to zero in ISR.
When to use timer ISR in a microcontroller?
Whenever a timer overflow occurs, Timer ISR will surely launch. In our labs, we normally use very high frequency crystals, and we don’t want our timer register overflowing too rapidly and the timer ISR being called again and again, so we need to call our timer less frequently and for that the frequency of crystal must be divided to a smaller value.
Is the ucontroller 18f46k22 an 8 bit timer?
Our uController 18F46K22 has 3 8-bit and 4 16-bit timers. The timer TMR0 module is an 8-bit timer/counter with the following features: 8-bit prescaler. Programmable internal or external clock source. Interrupt on overflow. Programmable external clock edge selection.
How to reduce the clock frequency to reduce microcontroller power?
It should be as less as possible to increase the device operation time. The power management is very critical in portable and battery-powered applications. Differences of microampere consumptions can lead to months or years of operating life which can increase or decrease the popularity and brand of the product in the market.
How does a high speed microcontroller conserve power?
The High-Speed Microcontroller family of microcontrollers supports different clock speed management modes that conserve power by slowing or stopping the internal clock. These modes allow the system developer to maximize power savings with a minimum impact on performance.
How is the output of the prescaler related to the timer?
The output of the prescaler is the clock input to the timer. By changing the number by which the prescaler divides the incoming clock, we can change the frequency of the timer clock even though the system clock frequency remains the same.
What are the features of a real time clock?
The first article describes the major features of most types of timers and covers periodic timers, and the second covers pulse width modulation MCU timers. Real-time clocks (RTC) are timers dedicated to maintaining a one-second timebase.
What kind of clock does an RTC use?
An RTC often has its own internal oscillator with an external crystal and an option to use an external frequency reference. All clock sources run at 32,768 Hz. An external clock source allows the use of a very accurate and stable device such as a TCXO (temperature-compensated crystal oscillator).