ATmega16U4 Registers – all 139 with their bits

PORTB I/O Port

PINBPort B Input Pins

Address: 0x23 I/O 0x03
Reset: 0x00
Access: read/write

7PINB7
6PINB6
5PINB5
4PINB4
3PINB3
2PINB2
1PINB1
0PINB0

DDRBPort B Data Direction Register

Address: 0x24 I/O 0x04
Reset: 0x00
Access: read/write

7DDB7
6DDB6
5DDB5
4DDB4
3DDB3
2DDB2
1DDB1
0DDB0

PORTBPort B Data Register

Address: 0x25 I/O 0x05
Reset: 0x00
Access: read/write

7PORTB7
6PORTB6
5PORTB5
4PORTB4
3PORTB3
2PORTB2
1PORTB1
0PORTB0

PORTC I/O Port

PINCPort C Input Pins

Address: 0x26 I/O 0x06
Reset: 0x00
Access: read/write

7PINC7
6PINC6
5–
4–
3–
2–
1–
0–

DDRCPort C Data Direction Register

Address: 0x27 I/O 0x07
Reset: 0x00
Access: read/write

7DDC7
6DDC6
5–
4–
3–
2–
1–
0–

PORTCPort C Data Register

Address: 0x28 I/O 0x08
Reset: 0x00
Access: read/write

7PORTC7
6PORTC6
5–
4–
3–
2–
1–
0–

PORTD I/O Port

PINDPort D Input Pins

Address: 0x29 I/O 0x09
Reset: 0x00
Access: read/write

7PIND7
6PIND6
5PIND5
4PIND4
3PIND3
2PIND2
1PIND1
0PIND0

DDRDPort D Data Direction Register

Address: 0x2A I/O 0x0A
Reset: 0x00
Access: read/write

7DDD7
6DDD6
5DDD5
4DDD4
3DDD3
2DDD2
1DDD1
0DDD0

PORTDPort D Data Register

Address: 0x2B I/O 0x0B
Reset: 0x00
Access: read/write

7PORTD7
6PORTD6
5PORTD5
4PORTD4
3PORTD3
2PORTD2
1PORTD1
0PORTD0

PORTE I/O Port

PINEInput Pins, Port E

Address: 0x2C I/O 0x0C
Reset: 0x00
Access: read/write

7–
6PINE6
5–
4–
3–
2PINE2
1–
0–

DDREData Direction Register, Port E

Address: 0x2D I/O 0x0D
Reset: 0x00
Access: read/write

7–
6DDE6
5–
4–
3–
2DDE2
1–
0–

PORTEData Register, Port E

Address: 0x2E I/O 0x0E
Reset: 0x00
Access: read/write

7–
6PORTE6
5–
4–
3–
2PORTE2
1–
0–

PORTF I/O Port

PINFInput Pins, Port F

Address: 0x2F I/O 0x0F
Reset: 0x00
Access: read/write

7PINF7
6PINF6
5PINF5
4PINF4
3–
2–
1PINF1
0PINF0

DDRFData Direction Register, Port F

Address: 0x30 I/O 0x10
Reset: 0x00
Access: read/write

7DDF7
6DDF6
5DDF5
4DDF4
3–
2–
1DDF1
0DDF0

PORTFData Register, Port F

Address: 0x31 I/O 0x11
Reset: 0x00
Access: read/write

7PORTF7
6PORTF6
5PORTF5
4PORTF4
3–
2–
1PORTF1
0PORTF0

TC0 Timer/Counter, 8-bit

TIFR0Timer/Counter0 Interrupt Flag register

Address: 0x35 I/O 0x15
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2OCF0B
1OCF0A
0TOV0

3 fields

Field	Bits	What it does
OCF0B	2	Timer/Counter0 Output Compare Flag 0B
OCF0A	1	Timer/Counter0 Output Compare Flag 0A
TOV0	0	Timer/Counter0 Overflow Flag

GTCCRGeneral Timer/Counter Control Register

Address: 0x43 I/O 0x23
Reset: 0x00
Access: read/write

7TSM
6–
5–
4–
3–
2–
1–
0PSRSYNC

2 fields

Field	Bits	What it does
TSM	7	Timer/Counter Synchronization Mode
PSRSYNC	0	Prescaler Reset Timer/Counter1 and Timer/Counter0

TCCR0ATimer/Counter Control Register A

Address: 0x44 I/O 0x24
Reset: 0x00
Access: read/write

7COM0A1
6COM0A0
5COM0B1
4COM0B0
3–
2–
1WGM01
0WGM00

3 fields

Field	Bits	What it does
COM0A	7:6	Compare Output Mode, Phase Correct PWM Mode
COM0B	5:4	Compare Output Mode, Fast PWm
WGM0	1:0	Waveform Generation Mode

TCCR0BTimer/Counter Control Register B

Address: 0x45 I/O 0x25
Reset: 0x00
Access: read/write

7FOC0A
6FOC0B
5–
4–
3WGM02
2CS02
1CS01
0CS00

4 fields

Field	Bits	What it does
FOC0A	7	Force Output Compare A
FOC0B	6	Force Output Compare B
WGM02	3
CS0	2:0	Clock Select `0` No Clock Source (Stopped) `1` Running, No Prescaling `2` Running, CLK/8 `3` Running, CLK/64 `4` Running, CLK/256 `5` Running, CLK/1024 `6` Running, ExtClk Tn Falling Edge `7` Running, ExtClk Tn Rising Edge

TCNT0Timer/Counter0

Address: 0x46 I/O 0x26
Reset: 0x00
Access: read/write

7TCNT07
6TCNT06
5TCNT05
4TCNT04
3TCNT03
2TCNT02
1TCNT01
0TCNT00

1 field

Field	Bits	What it does
TCNT0	7:0	Timer/Counter0 bits

OCR0ATimer/Counter0 Output Compare Register

Address: 0x47 I/O 0x27
Reset: 0x00
Access: read/write

7OCR0A7
6OCR0A6
5OCR0A5
4OCR0A4
3OCR0A3
2OCR0A2
1OCR0A1
0OCR0A0

1 field

Field	Bits	What it does
OCR0A	7:0	Timer/Counter0 Output Compare A bits

OCR0BTimer/Counter0 Output Compare Register

Address: 0x48 I/O 0x28
Reset: 0x00
Access: read/write

7OCR0B7
6OCR0B6
5OCR0B5
4OCR0B4
3OCR0B3
2OCR0B2
1OCR0B1
0OCR0B0

1 field

Field	Bits	What it does
OCR0B	7:0	Timer/Counter0 Output Compare B bits

TIMSK0Timer/Counter0 Interrupt Mask Register

Address: 0x6E
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2OCIE0B
1OCIE0A
0TOIE0

3 fields

Field	Bits	What it does
OCIE0B	2	Timer/Counter0 Output Compare Match B Interrupt Enable
OCIE0A	1	Timer/Counter0 Output Compare Match A Interrupt Enable
TOIE0	0	Timer/Counter0 Overflow Interrupt Enable

TC1 Timer/Counter, 16-bit

TIFR1Timer/Counter1 Interrupt Flag register

Address: 0x36 I/O 0x16
Reset: 0x00
Access: read/write

7–
6–
5ICF1
4–
3OCF1C
2OCF1B
1OCF1A
0TOV1

5 fields

Field	Bits	What it does
ICF1	5	Input Capture Flag 1
OCF1C	3	Output Compare Flag 1C
OCF1B	2	Output Compare Flag 1B
OCF1A	1	Output Compare Flag 1A
TOV1	0	Timer/Counter1 Overflow Flag

TIMSK1Timer/Counter1 Interrupt Mask Register

Address: 0x6F
Reset: 0x00
Access: read/write

7–
6–
5ICIE1
4–
3OCIE1C
2OCIE1B
1OCIE1A
0TOIE1

5 fields

Field	Bits	What it does
ICIE1	5	Timer/Counter1 Input Capture Interrupt Enable
OCIE1C	3	Timer/Counter1 Output Compare C Match Interrupt Enable
OCIE1B	2	Timer/Counter1 Output Compare B Match Interrupt Enable
OCIE1A	1	Timer/Counter1 Output Compare A Match Interrupt Enable
TOIE1	0	Timer/Counter1 Overflow Interrupt Enable

TCCR1ATimer/Counter1 Control Register A

Address: 0x80
Reset: 0x00
Access: read/write

7COM1A1
6COM1A0
5COM1B1
4COM1B0
3COM1C1
2COM1C0
1WGM11
0WGM10

4 fields

Field	Bits	What it does
COM1A	7:6	Compare Output Mode 1A, bits
COM1B	5:4	Compare Output Mode 1B, bits
COM1C	3:2	Compare Output Mode 1C, bits
WGM1	1:0	Waveform Generation Mode

TCCR1BTimer/Counter1 Control Register B

Address: 0x81
Reset: 0x00
Access: read/write

7ICNC1
6ICES1
5–
4WGM11
3WGM10
2CS12
1CS11
0CS10

4 fields

Field	Bits	What it does
ICNC1	7	Input Capture 1 Noise Canceler
ICES1	6	Input Capture 1 Edge Select
WGM1	4:3	Waveform Generation Mode
CS1	2:0	Prescaler source of Timer/Counter 1 `0` No Clock Source (Stopped) `1` Running, No Prescaling `2` Running, CLK/8 `3` Running, CLK/64 `4` Running, CLK/256 `5` Running, CLK/1024 `6` Running, ExtClk Tn Falling Edge `7` Running, ExtClk Tn Rising Edge

TCCR1CTimer/Counter 1 Control Register C

Address: 0x82
Reset: 0x00
Access: read/write

7FOC1A
6FOC1B
5FOC1C
4–
3–
2–
1–
0–

3 fields

Field	Bits	What it does
FOC1A	7	Force Output Compare 1A
FOC1B	6	Force Output Compare 1B
FOC1C	5	Force Output Compare 1C

TCNT1Timer/Counter1 Bytes

Address: 0x84
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
TCNT1	15:0	Timer/Counter1 bits

ICR1Timer/Counter1 Input Capture Register Bytes

Address: 0x86
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
ICR1	15:0	Timer/Counter1 Input Capture bits

OCR1ATimer/Counter1 Output Compare Register A Bytes

Address: 0x88
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
OCR1A	15:0	Timer/Counter1 Output Compare A bits

OCR1BTimer/Counter1 Output Compare Register B Bytes

Address: 0x8A
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
OCR1B	15:0	Timer/Counter1 Output Compare B bits

OCR1CTimer/Counter1 Output Compare Register C Bytes

Address: 0x8C
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
OCR1C	15:0	Timer/Counter1 Output Compare C bits

TC3 Timer/Counter, 16-bit

TIFR3Timer/Counter3 Interrupt Flag register

Address: 0x38 I/O 0x18
Reset: 0x00
Access: read/write

7–
6–
5ICF3
4–
3OCF3C
2OCF3B
1OCF3A
0TOV3

5 fields

Field	Bits	What it does
ICF3	5	Input Capture Flag 3
OCF3C	3	Output Compare Flag 3C
OCF3B	2	Output Compare Flag 3B
OCF3A	1	Output Compare Flag 3A
TOV3	0	Timer/Counter3 Overflow Flag

TIMSK3Timer/Counter3 Interrupt Mask Register

Address: 0x71
Reset: 0x00
Access: read/write

7–
6–
5ICIE3
4–
3OCIE3C
2OCIE3B
1OCIE3A
0TOIE3

5 fields

Field	Bits	What it does
ICIE3	5	Timer/Counter3 Input Capture Interrupt Enable
OCIE3C	3	Timer/Counter3 Output Compare C Match Interrupt Enable
OCIE3B	2	Timer/Counter3 Output Compare B Match Interrupt Enable
OCIE3A	1	Timer/Counter3 Output Compare A Match Interrupt Enable
TOIE3	0	Timer/Counter3 Overflow Interrupt Enable

TCCR3ATimer/Counter3 Control Register A

Address: 0x90
Reset: 0x00
Access: read/write

7COM3A1
6COM3A0
5COM3B1
4COM3B0
3COM3C1
2COM3C0
1WGM31
0WGM30

4 fields

Field	Bits	What it does
COM3A	7:6	Compare Output Mode 1A, bits
COM3B	5:4	Compare Output Mode 3B, bits
COM3C	3:2	Compare Output Mode 3C, bits
WGM3	1:0	Waveform Generation Mode

TCCR3BTimer/Counter3 Control Register B

Address: 0x91
Reset: 0x00
Access: read/write

7ICNC3
6ICES3
5–
4WGM31
3WGM30
2CS32
1CS31
0CS30

4 fields

Field	Bits	What it does
ICNC3	7	Input Capture 3 Noise Canceler
ICES3	6	Input Capture 3 Edge Select
WGM3	4:3	Waveform Generation Mode
CS3	2:0	Prescaler source of Timer/Counter 3 `0` No Clock Source (Stopped) `1` Running, No Prescaling `2` Running, CLK/8 `3` Running, CLK/64 `4` Running, CLK/256 `5` Running, CLK/1024 `6` Running, ExtClk Tn Falling Edge `7` Running, ExtClk Tn Rising Edge

TCCR3CTimer/Counter 3 Control Register C

Address: 0x92
Reset: 0x00
Access: read/write

7FOC3A
6FOC3B
5FOC3C
4–
3–
2–
1–
0–

3 fields

Field	Bits	What it does
FOC3A	7	Force Output Compare 3A
FOC3B	6	Force Output Compare 3B
FOC3C	5	Force Output Compare 3C

TCNT3Timer/Counter3 Bytes

Address: 0x94
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
TCNT3	15:0	Timer/Counter3 bits

ICR3Timer/Counter3 Input Capture Register Bytes

Address: 0x96
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
ICR3	15:0	Timer/Counter3 Input Capture bits

OCR3ATimer/Counter3 Output Compare Register A Bytes

Address: 0x98
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
OCR3A	15:0	Timer/Counter3 Output Compare A bits

OCR3BTimer/Counter3 Output Compare Register B Bytes

Address: 0x9A
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
OCR3B	15:0	Timer/Counter3 Output Compare B bits

OCR3CTimer/Counter3 Output Compare Register C Bytes

Address: 0x9C
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
OCR3C	15:0	Timer/Counter3 Output Compare C bits

TC4 Timer/Counter, 10-bit

TIFR4Timer/Counter4 Interrupt Flag register

Address: 0x39 I/O 0x19
Reset: 0x00
Access: read/write

7OCF4D
6OCF4A
5OCF4B
4–
3–
2TOV4
1–
0–

4 fields

Field	Bits	What it does
OCF4D	7	Output Compare Flag 4D
OCF4A	6	Output Compare Flag 4A
OCF4B	5	Output Compare Flag 4B
TOV4	2	Timer/Counter4 Overflow Flag

TIMSK4Timer/Counter4 Interrupt Mask Register

Address: 0x72
Reset: 0x00
Access: read/write

7OCIE4D
6OCIE4A
5OCIE4B
4–
3–
2TOIE4
1–
0–

4 fields

Field	Bits	What it does
OCIE4D	7	Timer/Counter4 Output Compare D Match Interrupt Enable
OCIE4A	6	Timer/Counter4 Output Compare A Match Interrupt Enable
OCIE4B	5	Timer/Counter4 Output Compare B Match Interrupt Enable
TOIE4	2	Timer/Counter4 Overflow Interrupt Enable

TCNT4Timer/Counter4 Low Bytes

Address: 0xBE
Reset: 0x00
Access: read/write

7TC47
6TC46
5TC45
4TC44
3TC43
2TC42
1TC41
0TC40

1 field

Field	Bits	What it does
TC4	7:0	Timer/Counter4 bits

TC4HTimer/Counter4

Address: 0xBF
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2TC42
1TC41
0TC40

1 field

Field	Bits	What it does
TC4	2:0	Timer/Counter4 bits

TCCR4ATimer/Counter4 Control Register A

Address: 0xC0
Reset: 0x00
Access: read/write

7COM4A1
6COM4A0
5COM4B1
4COM4B0
3FOC4A
2FOC4B
1PWM4A
0PWM4B

6 fields

Field	Bits	What it does
COM4A	7:6	Compare Output Mode 1A, bits
COM4B	5:4	Compare Output Mode 4B, bits
FOC4A	3	Force Output Compare Match 4A
FOC4B	2	Force Output Compare Match 4B
PWM4A	1
PWM4B	0

TCCR4BTimer/Counter4 Control Register B

Address: 0xC1
Reset: 0x00
Access: read/write

7PWM4X
6PSR4
5DTPS41
4DTPS40
3CS43
2CS42
1CS41
0CS40

4 fields

Field	Bits	What it does
PWM4X	7	PWM Inversion Mode
PSR4	6	Prescaler Reset Timer/Counter 4
DTPS4	5:4	Dead Time Prescaler Bits
CS4	3:0	Clock Select Bits

TCCR4CTimer/Counter 4 Control Register C

Address: 0xC2
Reset: 0x00
Access: read/write

7COM4A1S
6COM4A0S
5COM4B1S
4COM4B0S
3COM4D1
2COM4D0
1FOC4D
0PWM4D

7 fields

Field	Bits	What it does
COM4A1S	7	Comparator A Output Mode
COM4A0S	6	Comparator A Output Mode
COM4B1S	5	Comparator B Output Mode
COM4B0S	4	Comparator B Output Mode
COM4D	3:2	Comparator D Output Mode
FOC4D	1	Force Output Compare Match 4D
PWM4D	0	Pulse Width Modulator D Enable

TCCR4DTimer/Counter 4 Control Register D

Address: 0xC3
Reset: 0x00
Access: read/write

7FPIE4
6FPEN4
5FPNC4
4FPES4
3FPAC4
2FPF4
1WGM41
0WGM40

7 fields

Field	Bits	What it does
FPIE4	7	Fault Protection Interrupt Enable
FPEN4	6	Fault Protection Mode Enable
FPNC4	5	Fault Protection Noise Canceler
FPES4	4	Fault Protection Edge Select
FPAC4	3	Fault Protection Analog Comparator Enable
FPF4	2	Fault Protection Interrupt Flag
WGM4	1:0	Waveform Generation Mode bits

TCCR4ETimer/Counter 4 Control Register E

Address: 0xC4
Reset: 0x00
Access: read/write

7TLOCK4
6ENHC4
5OC4OE5
4OC4OE4
3OC4OE3
2OC4OE2
1OC4OE1
0OC4OE0

3 fields

Field	Bits	What it does
TLOCK4	7	Register Update Lock
ENHC4	6	Enhanced Compare/PWM Mode
OC4OE	5:0	Output Compare Override Enable bit

OCR4ATimer/Counter4 Output Compare Register A

Address: 0xCF
Reset: 0x00
Access: read/write

7OCR4A7
6OCR4A6
5OCR4A5
4OCR4A4
3OCR4A3
2OCR4A2
1OCR4A1
0OCR4A0

1 field

Field	Bits	What it does
OCR4A	7:0	Timer/Counter4 Output Compare A bits

OCR4BTimer/Counter4 Output Compare Register B

Address: 0xD0
Reset: 0x00
Access: read/write

7OCR4B7
6OCR4B6
5OCR4B5
4OCR4B4
3OCR4B3
2OCR4B2
1OCR4B1
0OCR4B0

1 field

Field	Bits	What it does
OCR4B	7:0	Timer/Counter4 Output Compare B bits

OCR4CTimer/Counter4 Output Compare Register C

Address: 0xD1
Reset: 0x00
Access: read/write

7OCR4C7
6OCR4C6
5OCR4C5
4OCR4C4
3OCR4C3
2OCR4C2
1OCR4C1
0OCR4C0

1 field

Field	Bits	What it does
OCR4C	7:0	Timer/Counter4 Output Compare C bits

OCR4DTimer/Counter4 Output Compare Register D

Address: 0xD2
Reset: 0x00
Access: read/write

7OCR4D7
6OCR4D6
5OCR4D5
4OCR4D4
3OCR4D3
2OCR4D2
1OCR4D1
0OCR4D0

1 field

Field	Bits	What it does
OCR4D	7:0	Timer/Counter4 Output Compare D bits

DT4Timer/Counter 4 Dead Time Value

Address: 0xD4
Reset: 0x00
Access: read/write

7DT4L7
6DT4L6
5DT4L5
4DT4L4
3DT4L3
2DT4L2
1DT4L1
0DT4L0

1 field

Field	Bits	What it does
DT4L	7:0	Timer/Counter 4 Dead Time Value Bits

EXINT External Interrupts

PCIFRPin Change Interrupt Flag Register

Address: 0x3B I/O 0x1B
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0PCIF0

1 field

Field	Bits	What it does
PCIF0	0	Pin Change Interrupt Flag 0

EIFRExternal Interrupt Flag Register

Address: 0x3C I/O 0x1C
Reset: 0x00
Access: read/write

7INTF7
6INTF6
5INTF5
4INTF4
3INTF3
2INTF2
1INTF1
0INTF0

1 field

Field	Bits	What it does
INTF	7:0	External Interrupt Flags

EIMSKExternal Interrupt Mask Register

Address: 0x3D I/O 0x1D
Reset: 0x00
Access: read/write

7INT7
6INT6
5INT5
4INT4
3INT3
2INT2
1INT1
0INT0

1 field

Field	Bits	What it does
INT	7:0	External Interrupt Request 7 Enable

PCICRPin Change Interrupt Control Register

Address: 0x68
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0PCIE0

1 field

Field	Bits	What it does
PCIE0	0	Pin Change Interrupt Enable 0

EICRAExternal Interrupt Control Register A

Address: 0x69
Reset: 0x00
Access: read/write

7ISC31
6ISC30
5ISC21
4ISC20
3ISC11
2ISC10
1ISC01
0ISC00

4 fields

Field	Bits	What it does
ISC3	7:6	External Interrupt Sense Control Bit `0` Low Level of INTX `1` Any Logical Change of INTX `2` Falling Edge of INTX `3` Rising Edge of INTX
ISC2	5:4	External Interrupt Sense Control Bit `0` Low Level of INTX `1` Any Logical Change of INTX `2` Falling Edge of INTX `3` Rising Edge of INTX
ISC1	3:2	External Interrupt Sense Control Bit `0` Low Level of INTX `1` Any Logical Change of INTX `2` Falling Edge of INTX `3` Rising Edge of INTX
ISC0	1:0	External Interrupt Sense Control Bit `0` Low Level of INTX `1` Any Logical Change of INTX `2` Falling Edge of INTX `3` Rising Edge of INTX

EICRBExternal Interrupt Control Register B

Address: 0x6A
Reset: 0x00
Access: read/write

7ISC71
6ISC70
5ISC61
4ISC60
3ISC51
2ISC50
1ISC41
0ISC40

4 fields

Field	Bits	What it does
ISC7	7:6	External Interrupt 7-4 Sense Control Bit `0` Low Level of INTX `1` Any Logical Change of INTX `2` Falling Edge of INTX `3` Rising Edge of INTX
ISC6	5:4	External Interrupt 7-4 Sense Control Bit `0` Low Level of INTX `1` Any Logical Change of INTX `2` Falling Edge of INTX `3` Rising Edge of INTX
ISC5	3:2	External Interrupt 7-4 Sense Control Bit `0` Low Level of INTX `1` Any Logical Change of INTX `2` Falling Edge of INTX `3` Rising Edge of INTX
ISC4	1:0	External Interrupt 7-4 Sense Control Bit `0` Low Level of INTX `1` Any Logical Change of INTX `2` Falling Edge of INTX `3` Rising Edge of INTX

PCMSK0Pin Change Mask Register 0

Address: 0x6B
Reset: 0x00
Access: read/write

7PCINT7
6PCINT6
5PCINT5
4PCINT4
3PCINT3
2PCINT2
1PCINT1
0PCINT0

1 field

Field	Bits	What it does
PCINT	7:0	Pin Change Mask 0

CPU CPU Registers

GPIOR0General Purpose IO Register 0

Address: 0x3E I/O 0x1E
Reset: 0x00
Access: read/write

7GPIOR07
6GPIOR06
5GPIOR05
4GPIOR04
3GPIOR03
2GPIOR02
1GPIOR01
0GPIOR00

8 fields

Field	Bits	What it does
GPIOR07	7	General Purpose IO Register 0 bit 7
GPIOR06	6	General Purpose IO Register 0 bit 6
GPIOR05	5	General Purpose IO Register 0 bit 5
GPIOR04	4	General Purpose IO Register 0 bit 4
GPIOR03	3	General Purpose IO Register 0 bit 3
GPIOR02	2	General Purpose IO Register 0 bit 2
GPIOR01	1	General Purpose IO Register 0 bit 1
GPIOR00	0	General Purpose IO Register 0 bit 0

GPIOR1General Purpose IO Register 1

Address: 0x4A I/O 0x2A
Reset: 0x00
Access: read/write

7GPIOR7
6GPIOR6
5GPIOR5
4GPIOR4
3GPIOR3
2GPIOR2
1GPIOR1
0GPIOR0

1 field

Field	Bits	What it does
GPIOR	7:0	General Purpose IO Register 1 bis

GPIOR2General Purpose IO Register 2

Address: 0x4B I/O 0x2B
Reset: 0x00
Access: read/write

7GPIOR7
6GPIOR6
5GPIOR5
4GPIOR4
3GPIOR3
2GPIOR2
1GPIOR1
0GPIOR0

1 field

Field	Bits	What it does
GPIOR	7:0	General Purpose IO Register 2 bis

SMCRSleep Mode Control Register

Address: 0x53 I/O 0x33
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3SM2
2SM1
1SM0
0SE

2 fields

Field	Bits	What it does
SM	3:1	Sleep Mode Select bits `0` Idle `1` ADC Noise Reduction (If Available) `2` Power Down `3` Power Save `4` Reserved `5` Reserved `6` Standby `7` Extended Standby
SE	0	Sleep Enable

MCUSRMCU Status Register

Address: 0x54 I/O 0x34
Reset: 0x00
Access: read/write

7–
6–
5–
4JTRF
3WDRF
2BORF
1EXTRF
0PORF

5 fields

Field	Bits	What it does
JTRF	4	JTAG Reset Flag
WDRF	3	Watchdog Reset Flag
BORF	2	Brown-out Reset Flag
EXTRF	1	External Reset Flag
PORF	0	Power-on reset flag

MCUCRMCU Control Register

Address: 0x55 I/O 0x35
Reset: 0x00
Access: read/write

7JTD
6–
5–
4PUD
3–
2–
1IVSEL
0IVCE

4 fields

Field	Bits	What it does
JTD	7	JTAG Interface Disable
PUD	4	Pull-up disable
IVSEL	1	Interrupt Vector Select
IVCE	0	Interrupt Vector Change Enable

RAMPZExtended Z-pointer Register for ELPM/SPM

Address: 0x5B I/O 0x3B
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1RAMPZ1
0RAMPZ0

1 field

Field	Bits	What it does
RAMPZ	1:0	Extended Z-Pointer Value `0` Default value of Z-pointer MSB's.

EINDExtended Indirect Register

Address: 0x5C I/O 0x3C
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0–

SPStack Pointer

Address: 0x5D I/O 0x3D
Reset: 0x05FF
Access: read/write
Size: 16-bit

SREGStatus Register

Address: 0x5F I/O 0x3F
Reset: 0x00
Access: read/write

7I
6T
5H
4S
3V
2N
1Z
0C

8 fields

Field	Bits	What it does
I	7	Global Interrupt Enable
T	6	Bit Copy Storage
H	5	Half Carry Flag
S	4	Sign Bit
V	3	Two's Complement Overflow Flag
N	2	Negative Flag
Z	1	Zero Flag
C	0	Carry Flag

CLKPR

Address: 0x61
Reset: 0x00
Access: read/write

7CLKPCE
6–
5–
4–
3CLKPS3
2CLKPS2
1CLKPS1
0CLKPS0

2 fields

Field	Bits	What it does
CLKPCE	7
CLKPS	3:0	`0` 1 `1` 2 `2` 4 `3` 8 `4` 16 `5` 32 `6` 64 `7` 128 `8` 256

PRR0Power Reduction Register0

Address: 0x64
Reset: 0x00
Access: read/write

7PRTWI
6PRTIM2
5PRTIM0
4–
3PRTIM1
2PRSPI
1PRUSART0
0PRADC

7 fields

Field	Bits	What it does
PRTWI	7	Power Reduction TWI
PRTIM2	6	Power Reduction Timer/Counter2
PRTIM0	5	Power Reduction Timer/Counter0
PRTIM1	3	Power Reduction Timer/Counter1
PRSPI	2	Power Reduction Serial Peripheral Interface
PRUSART0	1	Power Reduction USART
PRADC	0	Power Reduction ADC

PRR1Power Reduction Register1

Address: 0x65
Reset: 0x00
Access: read/write

7PRUSB
6–
5–
4PRTIM4
3PRTIM3
2–
1–
0PRUSART1

4 fields

Field	Bits	What it does
PRUSB	7	Power Reduction USB
PRTIM4	4	Power Reduction Timer/Counter4
PRTIM3	3	Power Reduction Timer/Counter3
PRUSART1	0	Power Reduction USART1

OSCCALOscillator Calibration Value

Address: 0x66
Reset: 0x00
Access: read/write

7OSCCAL7
6OSCCAL6
5OSCCAL5
4OSCCAL4
3OSCCAL3
2OSCCAL2
1OSCCAL1
0OSCCAL0

1 field

Field	Bits	What it does
OSCCAL	7:0	Oscillator Calibration

RCCTRLOscillator Control Register

Address: 0x67
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0RCFREQ

1 field

Field	Bits	What it does
RCFREQ	0

CLKSEL0

Address: 0xC5
Reset: 0x00
Access: read/write

7RCSUT1
6RCSUT0
5EXSUT1
4EXSUT0
3RCE
2EXTE
1–
0CLKS

5 fields

Field	Bits	What it does
RCSUT	7:6
EXSUT	5:4
RCE	3
EXTE	2
CLKS	0

CLKSEL1

Address: 0xC6
Reset: 0x00
Access: read/write

7RCCKSEL3
6RCCKSEL2
5RCCKSEL1
4RCCKSEL0
3EXCKSEL3
2EXCKSEL2
1EXCKSEL1
0EXCKSEL0

2 fields

Field	Bits	What it does
RCCKSEL	7:4
EXCKSEL	3:0

CLKSTA

Address: 0xC7
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1RCON
0EXTON

2 fields

Field	Bits	What it does
RCON	1
EXTON	0

EEPROM EEPROM

EECREEPROM Control Register

Address: 0x3F I/O 0x1F
Reset: 0x00
Access: read/write

7–
6–
5EEPM1
4EEPM0
3EERIE
2EEMPE
1EEPE
0EERE

5 fields

Field	Bits	What it does
EEPM	5:4	EEPROM Programming Mode Bits `0` Erase and Write in one operation `1` Erase Only `2` Write Only
EERIE	3	EEPROM Ready Interrupt Enable
EEMPE	2	EEPROM Master Write Enable
EEPE	1	EEPROM Write Enable
EERE	0	EEPROM Read Enable

EEDREEPROM Data Register

Address: 0x40 I/O 0x20
Reset: 0x00
Access: read/write

7EEDR7
6EEDR6
5EEDR5
4EEDR4
3EEDR3
2EEDR2
1EEDR1
0EEDR0

1 field

Field	Bits	What it does
EEDR	7:0	EEPROM Data Bits

EEAREEPROM Address Register Low Bytes

Address: 0x41 I/O 0x21
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
EEAR	11:0	EEPROM Address Bits

PLL Phase Locked Loop

PLLCSRPLL Status and Control register

Address: 0x49 I/O 0x29
Reset: 0x00
Access: read/write

7–
6–
5–
4PINDIV
3–
2–
1PLLE
0PLOCK

3 fields

Field	Bits	What it does
PINDIV	4	PLL prescaler Bit 2
PLLE	1	PLL Enable Bit
PLOCK	0	PLL Lock Status Bit

PLLFRQPLL Frequency Control Register

Address: 0x52 I/O 0x32
Reset: 0x00
Access: read/write

7PINMUX
6PLLUSB
5PLLTM1
4PLLTM0
3PDIV3
2PDIV2
1PDIV1
0PDIV0

4 fields

Field	Bits	What it does
PINMUX	7
PLLUSB	6
PLLTM	5:4
PDIV	3:0

SPI Serial Peripheral Interface

SPCRSPI Control Register

Address: 0x4C I/O 0x2C
Reset: 0x00
Access: read/write

7SPIE
6SPE
5DORD
4MSTR
3CPOL
2CPHA
1SPR1
0SPR0

7 fields

Field	Bits	What it does
SPIE	7	SPI Interrupt Enable
SPE	6	SPI Enable
DORD	5	Data Order
MSTR	4	Master/Slave Select
CPOL	3	Clock polarity
CPHA	2	Clock Phase
SPR	1:0	SPI Clock Rate Selects `0` fosc/4 `1` fosc/16 `2` fosc/64 `3` fosc/128 `4` fosc/2 `5` fosc/8 `6` fosc/32 `7` fosc/64

SPSRSPI Status Register

Address: 0x4D I/O 0x2D
Reset: 0x00
Access: read/write

7SPIF
6WCOL
5–
4–
3–
2–
1–
0SPI2X

3 fields

Field	Bits	What it does
SPIF	7	SPI Interrupt Flag
WCOL	6	Write Collision Flag
SPI2X	0	Double SPI Speed Bit

SPDRSPI Data Register

Address: 0x4E I/O 0x2E
Reset: 0x00
Access: read/write

7SPDR7
6SPDR6
5SPDR5
4SPDR4
3SPDR3
2SPDR2
1SPDR1
0SPDR0

1 field

Field	Bits	What it does
SPDR	7:0	SPI Data bits

AC Analog Comparator

ACSRAnalog Comparator Control And Status Register

Address: 0x50 I/O 0x30
Reset: 0x00
Access: read/write

7ACD
6ACBG
5ACO
4ACI
3ACIE
2ACIC
1ACIS1
0ACIS0

7 fields

Field	Bits	What it does
ACD	7	Analog Comparator Disable
ACBG	6	Analog Comparator Bandgap Select
ACO	5	Analog Compare Output
ACI	4	Analog Comparator Interrupt Flag
ACIE	3	Analog Comparator Interrupt Enable
ACIC	2	Analog Comparator Input Capture Enable
ACIS	1:0	Analog Comparator Interrupt Mode Select bits `0` Interrupt on Toggle `1` Reserved `2` Interrupt on Falling Edge `3` Interrupt on Rising Edge

ADCSRBADC Control and Status Register B

Address: 0x7B
Reset: 0x00
Access: read/write

7–
6ACME
5–
4–
3–
2–
1–
0–

1 field

Field	Bits	What it does
ACME	6	Analog Comparator Multiplexer Enable

DIDR1

Address: 0x7F
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1AIN1D
0AIN0D

2 fields

Field	Bits	What it does
AIN1D	1	AIN1 Digital Input Disable
AIN0D	0	AIN0 Digital Input Disable

JTAG JTAG Interface

OCDROn-Chip Debug Related Register in I/O Memory

Address: 0x51 I/O 0x31
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0–

MCUSRMCU Status Register

Address: 0x54 I/O 0x34
Reset: 0x00
Access: read/write

7–
6–
5–
4JTRF
3–
2–
1–
0–

1 field

Field	Bits	What it does
JTRF	4	JTAG Reset Flag

MCUCRMCU Control Register

Address: 0x55 I/O 0x35
Reset: 0x00
Access: read/write

7JTD
6–
5–
4–
3–
2–
1–
0–

1 field

Field	Bits	What it does
JTD	7	JTAG Interface Disable

BOOT_LOAD Bootloader

SPMCSRStore Program Memory Control Register

Address: 0x57 I/O 0x37
Reset: 0x00
Access: read/write

7SPMIE
6RWWSB
5SIGRD
4RWWSRE
3BLBSET
2PGWRT
1PGERS
0SPMEN

8 fields

Field	Bits	What it does
SPMIE	7	SPM Interrupt Enable
RWWSB	6	Read While Write Section Busy
SIGRD	5	Signature Row Read
RWWSRE	4	Read While Write section read enable
BLBSET	3	Boot Lock Bit Set
PGWRT	2	Page Write
PGERS	1	Page Erase
SPMEN	0	Store Program Memory Enable

WDT Watchdog Timer

WDTCSRWatchdog Timer Control Register

Address: 0x60
Reset: 0x00
Access: read/write

7WDIF
6WDIE
5WDP5
4WDCE
3WDE
2WDP2
1WDP1
0WDP0

5 fields

Field	Bits	What it does
WDIF	7	Watchdog Timeout Interrupt Flag
WDIE	6	Watchdog Timeout Interrupt Enable
WDP	5,2,1,0	Watchdog Timer Prescaler Bits `0` Oscillator Cycles 2K `1` Oscillator Cycles 4K `2` Oscillator Cycles 8K `3` Oscillator Cycles 16K `4` Oscillator Cycles 32K `5` Oscillator Cycles 64K `6` Oscillator Cycles 128K `7` Oscillator Cycles 256K `8` Oscillator Cycles 512K `9` Oscillator Cycles 1024K
WDCE	4	Watchdog Change Enable
WDE	3	Watch Dog Enable

ADC Analog-to-Digital Converter

ADCADC Data Register Bytes

Address: 0x78
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
ADC	9:0	ADC Data Bits

ADCSRAThe ADC Control and Status register

Address: 0x7A
Reset: 0x00
Access: read/write

7ADEN
6ADSC
5ADATE
4ADIF
3ADIE
2ADPS2
1ADPS1
0ADPS0

6 fields

Field	Bits	What it does
ADEN	7	ADC Enable
ADSC	6	ADC Start Conversion
ADATE	5	ADC Auto Trigger Enable
ADIF	4	ADC Interrupt Flag
ADIE	3	ADC Interrupt Enable
ADPS	2:0	ADC Prescaler Select Bits `0` 2 `1` 2 `2` 4 `3` 8 `4` 16 `5` 32 `6` 64 `7` 128

ADCSRBADC Control and Status Register B

Address: 0x7B
Reset: 0x00
Access: read/write

7ADHSM
6–
5MUX5
4–
3ADTS3
2ADTS2
1ADTS1
0ADTS0

3 fields

Field	Bits	What it does
ADHSM	7	ADC High Speed Mode
MUX5	5	Analog Channel and Gain Selection Bits
ADTS	3:0	ADC Auto Trigger Sources `0` Free Running mode `1` Analog Comparator `2` External Interrupt Request 0 `3` Timer/Counter0 Compare Match A `4` Timer/Counter0 Overflow `5` Timer/Counter1 Compare Match B `6` Timer/Counter1 Overflow `7` Timer/Counter1 Capture Event

ADMUXThe ADC multiplexer Selection Register

Address: 0x7C
Reset: 0x00
Access: read/write

7REFS1
6REFS0
5ADLAR
4MUX4
3MUX3
2MUX2
1MUX1
0MUX0

3 fields

Field	Bits	What it does
REFS	7:6	Reference Selection Bits `0` AREF, Internal Vref turned off `1` AVCC with external capacitor at AREF pin `2` Reserved `3` Internal 2.56V Voltage Reference with external capacitor at AREF pin
ADLAR	5	Left Adjust Result
MUX	4:0	Analog Channel and Gain Selection Bits

DIDR2Digital Input Disable Register 1

Address: 0x7D
Reset: 0x00
Access: read/write

7–
6–
5ADC13D
4ADC12D
3ADC11D
2ADC10D
1ADC9D
0ADC8D

6 fields

Field	Bits	What it does
ADC13D	5	ADC13 Digital input Disable
ADC12D	4	ADC12 Digital input Disable
ADC11D	3	ADC11 Digital input Disable
ADC10D	2	ADC10 Digital input Disable
ADC9D	1	ADC9 Digital input Disable
ADC8D	0	ADC8 Digital input Disable

DIDR0Digital Input Disable Register 1

Address: 0x7E
Reset: 0x00
Access: read/write

7ADC7D
6ADC6D
5ADC5D
4ADC4D
3ADC3D
2ADC2D
1ADC1D
0ADC0D

8 fields

Field	Bits	What it does
ADC7D	7	ADC7 Digital input Disable
ADC6D	6	ADC6 Digital input Disable
ADC5D	5	ADC5 Digital input Disable
ADC4D	4	ADC4 Digital input Disable
ADC3D	3	ADC3 Digital input Disable
ADC2D	2	ADC2 Digital input Disable
ADC1D	1	ADC1 Digital input Disable
ADC0D	0	ADC0 Digital input Disable

TWI Two Wire Serial Interface

TWBRTWI Bit Rate register

Address: 0xB8
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0–

TWSRTWI Status Register

Address: 0xB9
Reset: 0x00
Access: read/write

7TWS4
6TWS3
5TWS2
4TWS1
3TWS0
2–
1TWPS1
0TWPS0

2 fields

Field	Bits	What it does
TWS	7:3	TWI Status
TWPS	1:0	TWI Prescaler `0` 1 `1` 4 `2` 16 `3` 64

TWARTWI (Slave) Address register

Address: 0xBA
Reset: 0x00
Access: read/write

7TWA6
6TWA5
5TWA4
4TWA3
3TWA2
2TWA1
1TWA0
0TWGCE

2 fields

Field	Bits	What it does
TWA	7:1	TWI (Slave) Address register Bits
TWGCE	0	TWI General Call Recognition Enable Bit

TWDRTWI Data register

Address: 0xBB
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0–

TWCRTWI Control Register

Address: 0xBC
Reset: 0x00
Access: read/write

7TWINT
6TWEA
5TWSTA
4TWSTO
3TWWC
2TWEN
1–
0TWIE

7 fields

Field	Bits	What it does
TWINT	7	TWI Interrupt Flag
TWEA	6	TWI Enable Acknowledge Bit
TWSTA	5	TWI Start Condition Bit
TWSTO	4	TWI Stop Condition Bit
TWWC	3	TWI Write Collision Flag
TWEN	2	TWI Enable Bit
TWIE	0	TWI Interrupt Enable

TWAMRTWI (Slave) Address Mask Register

Address: 0xBD
Reset: 0x00
Access: read/write

7TWAM6
6TWAM5
5TWAM4
4TWAM3
3TWAM2
2TWAM1
1TWAM0
0–

1 field

Field	Bits	What it does
TWAM	7:1

USART1 USART

UCSR1AUSART Control and Status Register A

Address: 0xC8
Reset: 0x00
Access: read/write

7RXC1
6TXC1
5UDRE1
4FE1
3DOR1
2UPE1
1U2X1
0MPCM1

8 fields

Field	Bits	What it does
RXC1	7	USART Receive Complete
TXC1	6	USART Transmit Complete
UDRE1	5	USART Data Register Empty
FE1	4	Framing Error
DOR1	3	Data overRun
UPE1	2	Parity Error
U2X1	1	Double the USART transmission speed
MPCM1	0	Multi-processor Communication Mode

UCSR1BUSART Control and Status Register B

Address: 0xC9
Reset: 0x00
Access: read/write

7RXCIE1
6TXCIE1
5UDRIE1
4RXEN1
3TXEN1
2UCSZ12
1RXB81
0TXB81

8 fields

Field	Bits	What it does
RXCIE1	7	RX Complete Interrupt Enable
TXCIE1	6	TX Complete Interrupt Enable
UDRIE1	5	USART Data register Empty Interrupt Enable
RXEN1	4	Receiver Enable
TXEN1	3	Transmitter Enable
UCSZ12	2	Character Size
RXB81	1	Receive Data Bit 8
TXB81	0	Transmit Data Bit 8

UCSR1CUSART Control and Status Register C

Address: 0xCA
Reset: 0x00
Access: read/write

7UMSEL11
6UMSEL10
5UPM11
4UPM10
3USBS1
2UCSZ11
1UCSZ10
0UCPOL1

5 fields

Field	Bits	What it does
UMSEL1	7:6	USART Mode Select `0` Asynchronous USART `1` Synchronous USART `3` Master SPI
UPM1	5:4	Parity Mode Bits `0` Disabled `1` Reserved `2` Enabled, Even Parity `3` Enabled, Odd Parity
USBS1	3	Stop Bit Select `0` 1-bit `1` 2-bit
UCSZ1	2:1	Character Size
UCPOL1	0	Clock Polarity

UCSR1DUSART Control and Status Register D

Address: 0xCB
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1CTSEN
0RTSEN

2 fields

Field	Bits	What it does
CTSEN	1	CTS Enable
RTSEN	0	RTS Enable

UBRR1USART Baud Rate Register Bytes

Address: 0xCC
Reset: 0x0000
Access: read/write
Size: 16-bit

UDR1USART I/O Data Register

Address: 0xCE
Reset: 0x00
Access: read/write

7UDR17
6UDR16
5UDR15
4UDR14
3UDR13
2UDR12
1UDR11
0UDR10

1 field

Field	Bits	What it does
UDR1	7:0	USART I/O Data bits

USB_DEVICE USB Device Registers

UHWCON

Address: 0xD7
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0UVREGE

1 field

Field	Bits	What it does
UVREGE	0

USBCONUSB General Control Register

Address: 0xD8
Reset: 0x00
Access: read/write

7USBE
6–
5FRZCLK
4OTGPADE
3–
2–
1–
0VBUSTE

4 fields

Field	Bits	What it does
USBE	7
FRZCLK	5
OTGPADE	4
VBUSTE	0

USBSTA

Address: 0xD9
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3SPEED
2–
1–
0VBUS

2 fields

Field	Bits	What it does
SPEED	3
VBUS	0

USBINT

Address: 0xDA
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2–
1–
0VBUSTI

1 field

Field	Bits	What it does
VBUSTI	0

UDCON

Address: 0xE0
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3RSTCPU
2LSM
1RMWKUP
0DETACH

4 fields

Field	Bits	What it does
RSTCPU	3
LSM	2	USB low speed mode
RMWKUP	1
DETACH	0

UDINT

Address: 0xE1
Reset: 0x00
Access: read/write

7–
6UPRSMI
5EORSMI
4WAKEUPI
3EORSTI
2SOFI
1–
0SUSPI

6 fields

Field	Bits	What it does
UPRSMI	6
EORSMI	5
WAKEUPI	4
EORSTI	3
SOFI	2
SUSPI	0

UDIEN

Address: 0xE2
Reset: 0x00
Access: read/write

7–
6UPRSME
5EORSME
4WAKEUPE
3EORSTE
2SOFE
1–
0SUSPE

6 fields

Field	Bits	What it does
UPRSME	6
EORSME	5
WAKEUPE	4
EORSTE	3
SOFE	2
SUSPE	0

UDADDR

Address: 0xE3
Reset: 0x00
Access: read/write

7ADDEN
6UADD6
5UADD5
4UADD4
3UADD3
2UADD2
1UADD1
0UADD0

2 fields

Field	Bits	What it does
ADDEN	7
UADD	6:0

UDFNUM

Address: 0xE4
Reset: 0x0000
Access: read/write
Size: 16-bit

1 field

Field	Bits	What it does
FNUM	10:0	Frame number value

UDMFN

Address: 0xE6
Reset: 0x00
Access: read/write

7–
6–
5–
4FNCERR
3–
2–
1–
0–

1 field

Field	Bits	What it does
FNCERR	4

UEINTX

Address: 0xE8
Reset: 0x00
Access: read/write

7FIFOCON
6NAKINI
5RWAL
4NAKOUTI
3RXSTPI
2RXOUTI
1STALLEDI
0TXINI

8 fields

Field	Bits	What it does
FIFOCON	7
NAKINI	6
RWAL	5
NAKOUTI	4
RXSTPI	3
RXOUTI	2
STALLEDI	1
TXINI	0

UENUM

Address: 0xE9
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2UENUM2
1UENUM1
0UENUM0

1 field

Field	Bits	What it does
UENUM	2:0

UERST

Address: 0xEA
Reset: 0x00
Access: read/write

7–
6EPRST6
5EPRST5
4EPRST4
3EPRST3
2EPRST2
1EPRST1
0EPRST0

1 field

Field	Bits	What it does
EPRST	6:0

UECONX

Address: 0xEB
Reset: 0x00
Access: read/write

7–
6–
5STALLRQ
4STALLRQC
3RSTDT
2–
1–
0EPEN

4 fields

Field	Bits	What it does
STALLRQ	5
STALLRQC	4
RSTDT	3
EPEN	0

UECFG0X

Address: 0xEC
Reset: 0x00
Access: read/write

7EPTYPE1
6EPTYPE0
5–
4–
3–
2–
1–
0EPDIR

2 fields

Field	Bits	What it does
EPTYPE	7:6
EPDIR	0

UECFG1X

Address: 0xED
Reset: 0x00
Access: read/write

7–
6EPSIZE2
5EPSIZE1
4EPSIZE0
3EPBK1
2EPBK0
1ALLOC
0–

3 fields

Field	Bits	What it does
EPSIZE	6:4
EPBK	3:2
ALLOC	1

UESTA0X

Address: 0xEE
Reset: 0x00
Access: read/write

7CFGOK
6OVERFI
5UNDERFI
4–
3DTSEQ1
2DTSEQ0
1NBUSYBK1
0NBUSYBK0

5 fields

Field	Bits	What it does
CFGOK	7
OVERFI	6
UNDERFI	5
DTSEQ	3:2
NBUSYBK	1:0

UESTA1X

Address: 0xEF
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2CTRLDIR
1CURRBK1
0CURRBK0

2 fields

Field	Bits	What it does
CTRLDIR	2
CURRBK	1:0

UEIENX

Address: 0xF0
Reset: 0x00
Access: read/write

7FLERRE
6NAKINE
5–
4NAKOUTE
3RXSTPE
2RXOUTE
1STALLEDE
0TXINE

7 fields

Field	Bits	What it does
FLERRE	7
NAKINE	6
NAKOUTE	4
RXSTPE	3
RXOUTE	2
STALLEDE	1
TXINE	0

UEDATX

Address: 0xF1
Reset: 0x00
Access: read/write

7DAT7
6DAT6
5DAT5
4DAT4
3DAT3
2DAT2
1DAT1
0DAT0

1 field

Field	Bits	What it does
DAT	7:0

UEBCLX

Address: 0xF2
Reset: 0x00
Access: read/write

7BYCT7
6BYCT6
5BYCT5
4BYCT4
3BYCT3
2BYCT2
1BYCT1
0BYCT0

1 field

Field	Bits	What it does
BYCT	7:0	Byte count bits

UEBCHX

Address: 0xF3
Reset: 0x00
Access: read/write

7–
6–
5–
4–
3–
2BYCT2
1BYCT1
0BYCT0

1 field

Field	Bits	What it does
BYCT	2:0	Byte count bits

UEINT

Address: 0xF4
Reset: 0x00
Access: read/write

7–
6EPINT6
5EPINT5
4EPINT4
3EPINT3
2EPINT2
1EPINT1
0EPINT0

1 field

Field	Bits	What it does
EPINT	6:0	Endpoint interrupt bits