Datasheet

unsigned char sreg;
unsigned int i;
/* Save global interrupt flag */
sreg = SREG;
/* Disable interrupts */
_CLI();
/* Set TCNTn to i */
TCNTn = i;
/* Restore global interrupt flag */
SREG = sreg;
}
Note:
1. The example code assumes that the part specific header file is included. For I/O
registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”, and
“SBI” instructions must be replaced with instructions that allow access to extended
I/O. Typically “LDS” and “STS” combined with “SBRS”, “SBRC”, “SBR”, and “CBR”.
19.4 Timer/Counter Clock Sources
The Timer/Counter can be clocked by an internal or an external clock source. The clock source is
selected by the clock select logic, which is controlled by the clock select bits in the Timer/Counter control
Register B (TCCRnB.CS[2:0]).
Related Links
Timer/Counter 0, 1, 3, 4 Prescalers
19.5 Counter Unit
The main part of the 16-bit Timer/Counter is the programmable 16-bit bi-directional counter unit, as
shown in the block diagram:
Figure 19-1. Counter Unit Block Diagram
TEMP (8-bit)
DATA BUS (8-bit)
TCNTn (16-bit Counter)
TCNTnH (8-bit) TCNTnL (8-bit)
Control Logic
Count
Clear
Direction
TOVn
(Int.Req.)
Clock Select
TOP BOTTOM
Tn
Edge
Detector
( From Prescaler )
clk
Tn
Note: The “n” in the register and bit names indicates the device number (n = 1, 3, 4 for Timer/Counter 1,
3, 4), and the “x” indicates Output Compare unit (A/B).
Table 19-2. Signal Description (Internal Signals)
Signal Name Description
Count Increment or decrement TCNTn by 1.
Direction Select between increment and decrement.
ATmega328PB
TC1, 3, 4 - 16-bit Timer/Counter1, 3, 4 with PWM
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001906C-page 162