ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 111

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

Registers
2490G–AVR–03/04
Figure 46. 16-bit Timer/Counter Block Diagram
Note:
The Timer/Counter (TCNTn), Output Compare Registers (OCRnA/B/C), and Input Cap-
ture Register (ICRn) are all 16-bit registers. Special procedures must be followed when
accessing the 16-bit registers. These procedures are described in the section “Access-
ing 16-bit Registers” on page 113. The Timer/Counter Control Registers (TCCRnA/B/C)
are 8-bit registers and have no CPU access restrictions. Interrupt requests (shorten as
Int.Req.) signals are all visible in the Timer Interrupt Flag Register (TIFR) and Extended
Timer Interrupt Flag Register (ETIFR). All interrupts are individually masked with the
Timer Interrupt Mask Register (TIMSK) and Extended Timer Interrupt Mask Register
(ETIMSK). (E)TIFR and (E)TIMSK are not shown in the figure since these registers are
shared by other timer units.
The Timer/Counter can be clocked internally, via the prescaler, or by an external clock
source on the Tn pin. The Clock Select logic block controls which clock source and edge
the Timer/Counter uses to increment (or decrement) its value. The Timer/Counter is
inactive when no clock source is selected. The output from the Clock Select logic is
referred to as the timer clock (clk
1. Refer to Figure 1 on page 2, Table 30 on page 72, and Table 39 on page 79 for
Timer/Counter1 and 3 pin placement and description.
Timer/Counter
TCCRxA
OCRxA
OCRxB
OCRxC
TCNTx
ICRx
=
=
=
Direction
Count
Clear
T
n
).
Control Logic
TOP
=
TCCRxB
Values
BOTTOM
Fixed
TOP
ICFx (Int.Req.)
TCLK
Detector
(1)
Edge
=
0
OCFxA
(Int.Req.)
OCFxB
(Int.Req.)
OCFxC
(Int.Req.)
TOVx
(Int.Req.)
Clock Select
Generation
Generation
Generation
( From Prescaler )
Waveform
Waveform
Waveform
Canceler
TCCRxC
Detector
ATmega64(L)
Noise
Edge
Comparator Ouput )
( From Analog
OCxA
OCxB
OCxC
ICPx
Tx
111