ATmega16U4 datasheet(140/408 Pages) ATMEL

140 / 408 page

140

7766D–AVR–01/09

ATmega16U4/ATmega32U4

Figure 15-1. Timer/Counter4 Block Diagram

15.2.1

Speed

The maximum speed of the Timer/Counter4 is 64 MHz. However, if a supply voltage below 4

volts is used, it is recommended to decrease the input frequency, because the Timer/Counter4

is not running fast enough on low voltage levels.

15.2.2

Accuracy

The Timer/Counter4 is a 10-bit Timer/Counter module that can alternatively be used as an 8-bit

Timer/Counter. The Timer/Counter4 registers are basically 8-bit registers, but on top of that

there is a 2-bit High Byte Register (TC4H) that can be used as a common temporary buffer to

access the two MSBs of the 10-bit Timer/Counter4 registers by the AVR CPU via the 8-bit data

bus, if the 10-bit accuracy is used. Whereas, if the two MSBs of the 10-bit registers are written to

zero the Timer/Counter4 is working as an 8-bit Timer/Counter. When reading the low byte of any

8-bit register the two MSBs are written to the TC4H register, and when writing the low byte of

any 8-bit register the two MSBs are written from the TC4H register. Special procedures must be

followed when accessing the 10-bit Timer/Counter4 values via the 8-bit data bus. These proce-

dures are described in the section “Accessing 10-Bit Registers” on page 160.

The Enhanced PWM mode allows to add a resolution bit to each Compare register A/B/D, while

the output frequency remains identical to a Normal PWM mode. That means that the TC4H reg-

ister contains one more bit that will be the MSB in a 11-bits enhanced PWM operation. See the

section “Enhanced Compare/PWM mode” on page 149 for details about this feature and how to

use it.

8-BIT DATABUS

T/C INT. FLAG

10-BIT COMPARATOR

8-BIT OUTPUT COMPARE

T/C INT. MASK

TIMER/COUNTER4

(TCNT4)

DIRECTION

TIMER/COUNTER4 CONTROL LOGIC

TOV4

OCF4B

OC4A

OCF4A

T/C CONTROL

10-BIT COMPARATOR

8-BIT OUTPUT COMPARE

T/C CONTROL

OC4A

OC4B

DEAD TIME GENERATOR

10-BIT COMPARATOR

8-BIT OUTPUT COMPARE

10-BIT COMPARATOR

8-BIT OUTPUT COMPARE

T/C CONTROL

OCF4D

OC4D

DEAD TIME GENERATOR

OCW4A

OCW4B

OCW4D

2-BIT HIGH BYTE

T/C CONTROL

10-BIT OUTPUT

COMPARE REGISTER B

10-BIT OUTPUT

COMPARE REGISTER C

10-BIT OUTPUT

COMPARE REGISTER D

10-BIT OUTPUT

COMPARE REGISTER A

CLEAR

COUNT

CLK

T/C CONTROL

FAULT_PROTECTION

ATmega16U4 Datasheet(PDF) 140 Page - ATMEL Corporation

ATmega16U4 Datasheet(HTML) 140 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL