1. Timers/Counters

2. Counter Register

3. Karşılaştırıcısız çözüm olur mu?
A Simple Design (Counting 4 People) First Design (Counter Register has initial value of zero)
Sensor
Karşılaştırıcısız çözüm olur mu?

4. Karşılaştırıcısız çözüm
A Simple Design (Counting 4 People) Second Design (Counter Register has initial value of 0xFC)
Sensor
Karşılaştırıcısız çözüm

5. A Simple Design (Making 4 Clock Cycles Delay)
Bu sayıcı bir sensör yerine periyodik bir saat sinyali ile tetiklendiği için bir zamanlayıcıya dönüşmüştür.

6. A Generic Timer/Counter
Delay generating
Counting
Wave-form generating

7. Timers/Counters in AVR ATMega328PU
Two 8-bit Timers/Counters (0-255)
Timer 0
Timer 2
One 16-bit Timer/Counter ( )
Timer 1

8. Timer Registers and Flags
TCNTn (Timer/CouNTer Register)
TOVn (Timer OVerflow Flag)
TCCRn (Timer/Counter Control Register)
OCRn (Output Compare Register)
OCFn (Output Compare Match Flag)
TIFRn (Timer Interrupt Flag Register)
TCCRn
TCNTn
TOVn =
OCFn
n 0, 1 veya 2 değerini alır.
OCRn

9. Normal Mode (Timer 0) 1 FF FE 2 1 TOV0 = 1 TOV0: 0xFF TCNT0 TOV TOV
time 1
TOV0 = 1 1
TOV0:

10. Example 1: Write a Program that Waits 14 Machine Cycles in Normal Mode.
$100
-$0E
$F2
$F2
Question: How to calculate the delay
generated by the timer?
Answer:
1) Calculate how much a machine clock lasts.
T= 1/f
2) Calculate how many machine clocks it
waits.
3) Delay = T * number of machine cycles

11. Finding Values to be Loaded into the Timer 0
Calculate the period of clock source.
Period = 1 / Frequency
E.g. For XTAL = 8 MHz  T = 1/8MHz
Divide the desired time delay by period of clock.
Perform n, where n is the decimal value we got in Step 2.
Set TCNT0 = n

12. CTC (Clear Timer on Compare Match) Mode (Timer 0)
TCNT0
0xFF
OCR0
OCF0
OCF0
OCF0
time
OCR0 xx 2 1
TOV0:
TOV0 = no change
OCF0 = 1 1
OCF0:

13. Prescaler

14. Timer 1 (A 16-bit Timer)

15. Timer 1 OCR1B (OCR1BH + OCR1BL) = TCCR1A TCCR1B
OCF1B
TCCR1A
TCCR1B
TCNT1 (TCNT1H + TCNT1L)
TOV1 =
OCF1A
OCR1A (OCR1AH + OCR1AL)

16. Timer 1 Registers

17. Timer Clock Selector (CS1x)6
Timer Clock Selector (CS1x) 7

18. Timer Mode Selector (WGM1x)

19. Wrap Times (Fcpu=16 MHz) TIMER 0 is 8-bit (0−255)
when prescaler = 1, reaches full count in 16 ms
when prescaler = 1024, full count in ms
TIMER 1 is 16-bit (0−65536)
when prescaler = 1, reaches full count in ms
when prescaler = 1024, full count in seconds
TIMER 2 is 8-bit (0−255)
These wrap times set limits on timed interrupts
makes TIMER 1 attractive, for its 16 bits

20. A Complete Timer 1 AVR C Example (V1) (Normal Mode)
Yoklama (Polling). Kesmeden Farkı?
Bayrağı Silmek İçin Set Etmek Gerekli??

21. A Complete Timer 1 AVR C Example (V2) (Normal Mode)

22. A Complete Timer 1 AVR C Example (CTC Mode)

23. AVR C Definitions for ATMega328P
The bit values WGM12, CS10, etc. are defined in iom328p.h
Its location is hardware/tools/avr/avr/include/avr/
For example:
#define CS10 0
#define CS11 1
#define CS12 2
#define WGM12 3
#define WGM13 4
#define ICES1 6
#define ICNC1 7
#define OCR1A _SFR_MEM16(0x88)
#define OCR1AL _SFR_MEM8(0x88)
#define OCR1AH _SFR_MEM8(0x89)
#define TIMER1_COMPA_vect _VECTOR(11) // Timer1 Compare Match A

24. Generating Large Delays
Using loop
Prescaler
Bigger counters

25. The Difference Between Timer 0 and Timer 2
CS02 CS01 CS00 Comment
Timer/Counter stopped
clk (No Prescaling)
clk / 8
clk / 64
clk / 256
clk / 1024
External clock on T0 (falling edge)
External clock on T0 (rising edge)
CS22 CS21 CS20 Comment
Timer/Counter stopped
clk (No Prescaling)
clk / 8
clk / 32
clk / 64
clk / 128
clk / 256
clk / 1024

26. Atmel AVR ATMega328P Mikrodenetleyicisinin Pinout Diyagramı