Datasheet

143
ATmega16U4/32U4 [DATASHEET]
Atmel-7766J-USB-ATmega16U4/32U4-Datasheet_04/2016
Figure 15-2. Timer/Counter4 Synchronization Register Block Diagram
15.2.5 Definitions
Many register and bit references in this section are written in general form. A lower case “n” replaces the
Timer/Counter number, in this case 0. A lower case “x” replaces the Output Compare Unit, in this case Compare
Unit A, B, C or D. However, when using the register or bit defines in a program, the precise form must be used,
i.e., TCNT4 for accessing Timer/Counter4 counter value and so on.
The definitions in the table are used extensively throughout the document.
8-BIT DATABUS
OCR4A OCR4A_SI
TCNT4_SO
OCR4B OCR4B_SI
OCR4C OCR4C_SI
TCCR4A TCCR4A_SI
TCCR4B TCCR4B_SI
TCNT4 TCNT4_SI
OCF4A OCF4A_SI
OCF4B OCF4B_SI
TOV4 TOV4_SI
TOV4_SO
OCF4B_SO
OCF4A_SO
TCNT4
S
A
S
A
PLLTM1:0
!= '00'
CK
PCK
(clk
TMR
)
IO-registers Input synchronization
registers
Timer/Counter4 Output synchronization
registers
SYNC
MODE
ASYNC
MODE
1 CK Delay 1/2 CK Delay
~1/2 CK Delay 1 PCK Delay 1 PCK Delay ~1 CK Delay
TCNT4
OCF4
OCF4B
TOV4
1/2 CK Delay 1 CK Delay
OCR4D OCR4D_SI
TC4H TC4H_SI
TCCR4C TCCR4C_SI
TCCR4D
OCF4D OCF4D_SI
OCF4D_SO
OCF4D
TC4H_SO
TC4H
TCCR4D_SI
BOTTOM The counter reaches the BOTTOM when it becomes 0.
MAX The counter reaches its MAXimum value when it becomes 0x3FF (decimal 1023).
TOP
The counter reaches the TOP value (stored in the OCR1C) when it becomes equal to the
highest value in the count sequence. The TOP has a value 0x0FF as default after reset.