
89
8008H–AVR–04/11
ATtiny48/88
12. 16-bit Timer/Counter1 with PWM
12.1
Features
True 16-bit Design (i.e., Allows 16-bit PWM)
Two independent Output Compare Units
Double Buffered Output Compare Registers
One Input Capture Unit
Input Capture Noise Canceler
Clear Timer on Compare Match (Auto Reload)
Glitch-free, Phase Correct Pulse Width Modulator (PWM)
Variable PWM Period
Frequency Generator
External Event Counter
Four independent interrupt Sources (TOV1, OCF1A, OCF1B, and ICF1)
12.2
Overview
Most register and bit references in this section are written in general form, where a lower case
“n” replaces the Timer/Counter number, and a lower case “x” replaces the Output Compare unit
channel. However, when using the register or bit defines in a program, the precise form must be
used, i.e., TCNT1 for accessing Timer/Counter1 counter value and so on.
The 16-bit Timer/Counter unit allows accurate program execution timing (event management),
wave generation, and signal timing measurement. A simplified block diagram of the 16-bit
Figure 12-1. 16-bit Timer/Counter Block Diagram
Note:
Timer/Counter1 pin placement and description.
Clock Select
Timer/Counter
D
ATA
B
U
S
OCRnA
OCRnB
ICRn
=
TCNTn
Waveform
Generation
Waveform
Generation
OCnA
OCnB
Noise
Canceler
ICPn
=
Fixed
TOP
Values
Edge
Detector
Control Logic
= 0
TOP
BOTTOM
Count
Clear
Direction
TOVn
(Int.Req.)
OCnA
(Int.Req.)
OCnB
(Int.Req.)
ICFn (Int.Req.)
TCCRnA
TCCRnB
( From Analog
Comparator Ouput )
Tn
Edge
Detector
( From Prescaler )
clk
Tn