AT90PWM2B-16SE ATMEL [ATMEL Corporation], AT90PWM2B-16SE Datasheet - Page 103

• Manufacturer Part Number: AT90PWM2B-16SE
• Description: 8-bit Microcontroller with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

15.1.1
4317J–AVR–08/10
Registers
Figure 15-1. 16-bit Timer/Counter Block Diagram
Note:
The Timer/Counter (TCNTn), Output Compare Registers (OCRnx), and Input Capture 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
104. The Timer/Counter Control Registers (TCCRnx) are 8-bit registers and have no CPU
access restrictions. Interrupt requests (abbreviated to Int.Req. in the figure) signals are all visible
in the Timer Interrupt Flag Register (TIFRn). All interrupts are individually masked with the Timer
Interrupt Mask Register (TIMSKn). TIFRn and TIMSKn are not shown in the figure.
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
The double buffered Output Compare Registers (OCRnx) are compared with the Timer/Counter
value at all time. The result of the compare can be used by the Waveform Generator to generate
a PWM or variable frequency output on the Output Compare pin (OCnx).
Units” on page 110.
which can be used to generate an Output Compare interrupt request.
1. Refer to
Table on page 4
Timer/Counter
The compare match event will also set the Compare Match Flag (OCFnx)
TCCRnA
OCRnA
OCRnB
TCNTn
ICRn
=
=
Direction
Count
Clear
for Timer/Counter1 pin placement and description.
Control Logic
TOP
=
TCCRnB
Values
BOTTOM
Fixed
TOP
ICFn (Int.Req.)
(1)
clk
Detector
Edge
=
Tn
0
AT90PWM2/3/2B/3B
“Accessing 16-bit Registers” on page
OCnA
(Int.Req.)
OCnB
(Int.Req.)
TOVn
(Int.Req.)
Clock Select
Generation
Generation
( From Prescaler )
Waveform
Waveform
Canceler
Detector
Noise
Edge
See “Output Compare
ICPSEL1
0
1
ICPnA
ICPnB
T
OCnA
OCnB
n
Tn
).
103