Timer/Counter on ATmega2560

The ATmega2560 has four timers/counters, each with its own set of registers and capabilities. These timers/counters can be used for a variety of purposes, including:

• Timing and counting: Timers/counters can be used to generate precise timing intervals or to count the number of events that occur.
• PWM generation: Timers/counters can be used to generate pulse-width modulated (PWM) signals, which are used in many applications, such as motor control and LED dimming.
• Output compare: Timers/counters can be used to generate an output pulse when a certain time interval has elapsed.

Timer/Counter Modes

The ATmega2560 timers/counters can operate in a variety of modes, each of which has its own advantages and disadvantages. The following are the four basic modes:

• Normal mode: In normal mode, the timer/counter increments its counter register at a rate determined by the clock source. When the counter register reaches a certain value, the timer/counter generates an overflow interrupt.
• Phase correct PWM mode: In phase correct PWM mode, the timer/counter generates a PWM signal with a duty cycle determined by the compare register. The duty cycle is the ratio of the time the output is high to the total period of the signal.
• Fast PWM mode: In fast PWM mode, the timer/counter generates a PWM signal with a duty cycle determined by the compare register. The output is always high, except when the counter register is equal to the compare register.
• CTC mode: In CTC mode, the timer/counter generates an output pulse when the counter register reaches a certain value. The output pulse width is determined by the difference between the counter register value and the compare register value.

ATmega2560 Timer/Counter Registers

Each ATmega2560 timer/counter has a set of registers that control its operation. The following are the most important registers:

• TCCRx: This register controls the clock source, mode of operation, and other features of the timer/counter.

TCCR0A in Atmega2560

TCCR0B in Atmega2560

• TCNTx: This register stores the current value of the counter.

TCNT0 register for 8-bit timer/counter

• OCRx: This register stores the compare register value.

Register OCR0A & OCR0B

Examples

Here are some examples of how timers/counters can be used on the ATmega2560:

• To generate a 1-second delay, you could set the TCNT0 register to 255 and the TCCR0 register to 0b00000010. This would set the timer/counter to operate in normal mode with a clock source of 1 MHz. The timer/counter would then overflow after 256 clock cycles, which is 1 second at a clock frequency of 1 MHz.
• To generate a 50% duty cycle PWM signal with a frequency of 1 kHz, you could set the TCCR1A register to 0b00000010 and the OCR1A register to 127. This would set the timer/counter to operate in phase correct PWM mode with a clock source of 1 MHz. The duty cycle would then be 50%, since the compare register value is halfway between the maximum and minimum values of the counter register.
• To generate an output pulse that is 2 milliseconds long, you could set the TCCR1A register to 0b00000010 and the OCR1A register to 250. This would set the timer/counter to operate in CTC mode with a clock source of 1 MHz. The output pulse would then be 2 milliseconds long, since the compare register value is 2 milliseconds after the current value of the counter register.

Conclusion

Timers/counters are a powerful tool that can be used for a variety of purposes on the ATmega2560. By understanding how timers/counters work, you can use them to create complex and sophisticated applications.