AI Interactive Datasheet ATtiny20
AVR · tinyAVR

ATtiny20 registers

All 61 registers by peripheral, at their data-space address (the I/O address IN and OUT use is shown beside it), with their reset value and every bit.

PORTA I/O Port

PINAPort A Input Pins

Address
0x00
Reset
0x00
Access
read/write
  1. 7PINA7
  2. 6PINA6
  3. 5PINA5
  4. 4PINA4
  5. 3PINA3
  6. 2PINA2
  7. 1PINA1
  8. 0PINA0

DDRAData Direction Register, Port A

Address
0x01
Reset
0x00
Access
read/write
  1. 7DDA7
  2. 6DDA6
  3. 5DDA5
  4. 4DDA4
  5. 3DDA3
  6. 2DDA2
  7. 1DDA1
  8. 0DDA0

PORTAPort A Data Register

Address
0x02
Reset
0x00
Access
read/write
  1. 7PORTA7
  2. 6PORTA6
  3. 5PORTA5
  4. 4PORTA4
  5. 3PORTA3
  6. 2PORTA2
  7. 1PORTA1
  8. 0PORTA0

PUEAPull-up Enable Control Register

Address
0x03
Reset
0x00
Access
read/write
  1. 7PUEA7
  2. 6PUEA6
  3. 5PUEA5
  4. 4PUEA4
  5. 3PUEA3
  6. 2PUEA2
  7. 1PUEA1
  8. 0PUEA0

PORTCRPort Control Register

Address
0x08
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0BBMA
1 field
FieldBitsWhat it does
BBMA0Break-Before-Make Mode Enable

PORTB I/O Port

PINBPort B Data register

Address
0x04
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3PINB3
  6. 2PINB2
  7. 1PINB1
  8. 0PINB0

DDRBData Direction Register, Port B

Address
0x05
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3DDB3
  6. 2DDB2
  7. 1DDB1
  8. 0DDB0

PORTBInput Pins, Port B

Address
0x06
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3PORTB3
  6. 2PORTB2
  7. 1PORTB1
  8. 0PORTB0

PUEBPull-up Enable Control Register

Address
0x07
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3PUEB3
  6. 2PUEB2
  7. 1PUEB1
  8. 0PUEB0

PORTCRPort Control Register

Address
0x08
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1BBMB
  8. 0–
1 field
FieldBitsWhat it does
BBMB1Break-Before-Make Mode Enable

EXINT External Interrupts

PCMSK0Pin Change Mask Register 0

Address
0x09
Reset
0x00
Access
read/write
  1. 7PCINT7
  2. 6PCINT6
  3. 5PCINT5
  4. 4PCINT4
  5. 3PCINT3
  6. 2PCINT2
  7. 1PCINT1
  8. 0PCINT0
1 field
FieldBitsWhat it does
PCINT7:0Pin Change Enable Masks

PCMSK1Pin Change Mask Register 1

Address
0x0A
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3PCINT3
  6. 2PCINT2
  7. 1PCINT1
  8. 0PCINT0
1 field
FieldBitsWhat it does
PCINT3:0Pin Change Enable Masks

GIFRGeneral Interrupt Flag Register

Address
0x0B
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5PCIF1
  4. 4PCIF0
  5. 3–
  6. 2–
  7. 1–
  8. 0INTF0
2 fields
FieldBitsWhat it does
PCIF5:4Pin Change Interrupt Flags
INTF00External Interrupt Flag 0

GIMSKGeneral Interrupt Mask Register

Address
0x0C
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5PCIE1
  4. 4PCIE0
  5. 3–
  6. 2–
  7. 1–
  8. 0INT0
2 fields
FieldBitsWhat it does
PCIE5:4Pin Change Interrupt Enables
INT00External Interrupt Request 0 Enable

MCUCRMCU Control Register

Address
0x3A I/O 0x1A
Reset
0x00
Access
read/write
  1. 7ISC01
  2. 6ISC00
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–
2 fields
FieldBitsWhat it does
ISC017Interrupt Sense Control 0 Bit 1
ISC006Interrupt Sense Control 0 Bit 0
  • 0 Low Level of INTX
  • 1 Any logical change on INTX
  • 2 Falling Edge of INTX
  • 3 Rising Edge of INTX

ADC Analog-to-Digital Converter

DIDR0Digital Input Disable Register 0

Address
0x0D
Reset
0x00
Access
read/write
  1. 7ADC7D
  2. 6ADC6D
  3. 5ADC5D
  4. 4ADC4D
  5. 3ADC3D
  6. 2ADC2D
  7. 1ADC1D
  8. 0ADC0D
8 fields
FieldBitsWhat it does
ADC7D7ADC6 Digital input Disable
ADC6D6ADC5 Digital input Disable
ADC5D5ADC4 Digital input Disable
ADC4D4ADC3 Digital input Disable
ADC3D3AREF Digital Input Disable
ADC2D2ADC2 Digital input Disable
ADC1D1ADC1 Digital input Disable
ADC0D0ADC0 Digital input Disable

ADCADC Data Register Bytes

Address
0x0E
Reset
0x0000
Access
read/write
Size
16-bit

ADMUXThe ADC multiplexer Selection Register

Address
0x10
Reset
0x00
Access
read/write
  1. 7–
  2. 6REFS
  3. 5–
  4. 4–
  5. 3MUX3
  6. 2MUX2
  7. 1MUX1
  8. 0MUX0
2 fields
FieldBitsWhat it does
REFS6Reference Selection Bit
  • 0 Vcc used as internal reference
  • 1 Internal 1.1V Reference
MUX3:0Analog Channel and Gain Selection Bits
  • 0 ADC0
  • 1 ADC1
  • 2 ADC2
  • 3 ADC3
  • 4 ADC4
  • 5 ADC5
  • 6 ADC6
  • 7 ADC7
  • 8 0V (AGND)
  • 9 1.1V Internal Reference
  • 10 Temperature sensor

ADCSRBADC Control and Status Register B

Address
0x11
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3ADLAR
  6. 2ADTS2
  7. 1ADTS1
  8. 0ADTS0
2 fields
FieldBitsWhat it does
ADLAR3
ADTS2:0ADC 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 Watchdog Interrupt Request

ADCSRAThe ADC Control and Status register

Address
0x12
Reset
0x00
Access
read/write
  1. 7ADEN
  2. 6ADSC
  3. 5ADATE
  4. 4ADIF
  5. 3ADIE
  6. 2ADPS2
  7. 1ADPS1
  8. 0ADPS0
6 fields
FieldBitsWhat it does
ADEN7ADC Enable
ADSC6ADC Start Conversion
ADATE5ADC Auto Trigger Enable
ADIF4ADC Interrupt Flag
ADIE3ADC Interrupt Enable
ADPS2:0ADC Prescaler Select Bits
  • 0 2
  • 1 2
  • 2 4
  • 3 8
  • 4 16
  • 5 32
  • 6 64
  • 7 128

AC Analog Comparator

ACSRBAnalog Comparator Control And Status Register B

Address
0x13
Reset
0x00
Access
read/write
  1. 7HSEL
  2. 6HLEV
  3. 5–
  4. 4–
  5. 3–
  6. 2ACME
  7. 1–
  8. 0–
3 fields
FieldBitsWhat it does
HSEL7Hysteresis Select
HLEV6Hysteresis Level
ACME2Analog Comparator Multiplexer Enable

ACSRAAnalog Comparator Control And Status Register A

Address
0x14
Reset
0x00
Access
read/write
  1. 7ACD
  2. 6ACBG
  3. 5ACO
  4. 4ACI
  5. 3ACIE
  6. 2ACIC
  7. 1ACIS1
  8. 0ACIS0
7 fields
FieldBitsWhat it does
ACD7Analog Comparator Disable
ACBG6Analog Comparator Bandgap Select
ACO5Analog Compare Output
ACI4Analog Comparator Interrupt Flag
ACIE3Analog Comparator Interrupt Enable
ACIC2Analog Comparator Input Capture Enable
ACIS1:0Analog Comparator Interrupt Mode Select bits
  • 0 Interrupt on Toggle
  • 1 Reserved
  • 2 Interrupt on Falling Edge
  • 3 Interrupt on Rising Edge

TC0 Timer/Counter, 8-bit

OCR0BTimer/Counter0 Output Compare Register

Address
0x15
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–

OCR0ATimer/Counter0 Output Compare Register

Address
0x16
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–

TCNT0Timer/Counter0

Address
0x17
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–

TCCR0BTimer/Counter 0 Control Register B

Address
0x18
Reset
0x00
Access
read/write
  1. 7FOC0A
  2. 6FOC0B
  3. 5–
  4. 4–
  5. 3WGM02
  6. 2CS02
  7. 1CS01
  8. 0CS00
4 fields
FieldBitsWhat it does
FOC0A7Force Output Compare A
FOC0B6Force Output Compare B
WGM023Waveform Generation Mode
CS02:0Clock 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

TCCR0ATimer/Counter 0 Control Register A

Address
0x19
Reset
0x00
Access
read/write
  1. 7COM0A1
  2. 6COM0A0
  3. 5COM0B1
  4. 4COM0B0
  5. 3–
  6. 2–
  7. 1WGM01
  8. 0WGM00
3 fields
FieldBitsWhat it does
COM0A7:6Compare Output Mode for Channel A bits
COM0B5:4Compare Output Mode for Channel B bits
WGM01:0Waveform Generation Mode

TIFROverflow Interrupt Enable

Address
0x25 I/O 0x05
Reset
0x00
Access
read/write
  1. 7ICF1
  2. 6–
  3. 5OCF1B
  4. 4OCF1A
  5. 3TOV3
  6. 2OCF0B
  7. 1OCF0A
  8. 0TOV0
6 fields
FieldBitsWhat it does
ICF17Input Capture Flag
OCF1B5Timer Output Compare Flag 1B
OCF1A4Timer Output Compare Flag 1A
TOV3,0Timer Overflow Flag
OCF0B2Output Compare Flag 0 B
OCF0A1Output Compare Flag 0 A

TIMSKTimer Interrupt Mask Register

Address
0x26 I/O 0x06
Reset
0x00
Access
read/write
  1. 7ICIE1
  2. 6–
  3. 5OCIE1B
  4. 4OCIE1A
  5. 3TOIE3
  6. 2OCIE0B
  7. 1OCIE0A
  8. 0TOIE0
6 fields
FieldBitsWhat it does
ICIE17Input Capture Interrupt Enable
OCIE1B5Output Compare B Match Interrupt Enable
OCIE1A4Output Compare A Match Interrupt Enable
TOIE3,0Overflow Interrupt Enable
OCIE0B2Timer/Counter Output Compare Match B Interrupt Enable
OCIE0A1Timer/Counter0 Output Compare Match A Interrupt Enable

GTCCRGeneral Timer/Counter Control Register

Address
0x27 I/O 0x07
Reset
0x00
Access
read/write
  1. 7TSM
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0PSR
2 fields
FieldBitsWhat it does
TSM7Timer Synchronization Mode
PSR0Prescaler Reset

TC1 Timer/Counter, 16-bit

ICR1Input Capture Register Bytes

Address
0x1A
Reset
0x0000
Access
read/write
Size
16-bit

OCR1BTimer/Counter1 Output Compare Register B

Address
0x1C
Reset
0x0000
Access
read/write
Size
16-bit

OCR1ATimer/Counter 1 Output Compare Register A

Address
0x1E
Reset
0x0000
Access
read/write
Size
16-bit

TCNT1Timer/Counter1

Address
0x20 I/O 0x00
Reset
0x0000
Access
read/write
Size
16-bit

TCCR1CTimer/Counter1 Control Register C

Address
0x22 I/O 0x02
Reset
0x00
Access
read/write
  1. 7FOC1A
  2. 6FOC1B
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–
2 fields
FieldBitsWhat it does
FOC1A7Force Output Compare for channel A
FOC1B6Force Output Compare for channel B

TCCR1BTimer/Counter1 Control Register B

Address
0x23 I/O 0x03
Reset
0x00
Access
read/write
  1. 7ICNC1
  2. 6ICES1
  3. 5–
  4. 4WGM11
  5. 3WGM10
  6. 2CS12
  7. 1CS11
  8. 0CS10
4 fields
FieldBitsWhat it does
ICNC17Input Capture 1 Noise Canceler
ICES16Input Capture 1 Edge Select
WGM14:3Waveform Generation Mode
CS12:0Clock Select1 bits
  • 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

TCCR1ATimer/Counter1 Control Register A

Address
0x24 I/O 0x04
Reset
0x00
Access
read/write
  1. 7COM1A1
  2. 6COM1A0
  3. 5COM1B1
  4. 4COM1B0
  5. 3–
  6. 2–
  7. 1WGM11
  8. 0WGM10
3 fields
FieldBitsWhat it does
COM1A7:6Compare Output Mode 1A, bits
COM1B5:4Compare Output Mode 1B, bits
WGM11:0Waveform Generation Mode Bits

TIFROverflow Interrupt Enable

Address
0x25 I/O 0x05
Reset
0x00
Access
read/write
  1. 7ICF1
  2. 6–
  3. 5OCF1B
  4. 4OCF1A
  5. 3TOV3
  6. 2OCF0B
  7. 1OCF0A
  8. 0TOV0
6 fields
FieldBitsWhat it does
ICF17Input Capture Flag
OCF1B5Timer Output Compare Flag 1B
OCF1A4Timer Output Compare Flag 1A
TOV3,0Timer Overflow Flag
OCF0B2Output Compare Flag 0 B
OCF0A1Output Compare Flag 0 A

TIMSKTimer Interrupt Mask Register

Address
0x26 I/O 0x06
Reset
0x00
Access
read/write
  1. 7ICIE1
  2. 6–
  3. 5OCIE1B
  4. 4OCIE1A
  5. 3TOIE3
  6. 2OCIE0B
  7. 1OCIE0A
  8. 0TOIE0
6 fields
FieldBitsWhat it does
ICIE17Input Capture Interrupt Enable
OCIE1B5Output Compare B Match Interrupt Enable
OCIE1A4Output Compare A Match Interrupt Enable
TOIE3,0Overflow Interrupt Enable
OCIE0B2Timer/Counter Output Compare Match B Interrupt Enable
OCIE0A1Timer/Counter0 Output Compare Match A Interrupt Enable

GTCCRGeneral Timer/Counter Control Register

Address
0x27 I/O 0x07
Reset
0x00
Access
read/write
  1. 7TSM
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0PSR
2 fields
FieldBitsWhat it does
TSM7Timer Synchronization Mode
PSR0Prescaler Reset

TWI Two Wire Serial Interface

TWSDTWI Slave Data Register

Address
0x28 I/O 0x08
Reset
0x00
Access
read/write
  1. 7TWSD7
  2. 6TWSD6
  3. 5TWSD5
  4. 4TWSD4
  5. 3TWSD3
  6. 2TWSD2
  7. 1TWSD1
  8. 0TWSD0
1 field
FieldBitsWhat it does
TWSD7:0TWI slave data bit

TWSAMTWI Slave Address Mask Register

Address
0x29 I/O 0x09
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–

TWSATWI Slave Address Register

Address
0x2A I/O 0x0A
Reset
0x00
Access
read/write
  1. 7TWSA7
  2. 6TWSA6
  3. 5TWSA5
  4. 4TWSA4
  5. 3TWSA3
  6. 2TWSA2
  7. 1TWSA1
  8. 0TWSA0
1 field
FieldBitsWhat it does
TWSA7:0TWI slave address bit

TWSSRATWI Slave Status Register A

Address
0x2B I/O 0x0B
Reset
0x00
Access
read/write
  1. 7TWDIF
  2. 6TWASIF
  3. 5TWCH
  4. 4TWRA
  5. 3TWC
  6. 2TWBE
  7. 1TWDIR
  8. 0TWAS
8 fields
FieldBitsWhat it does
TWDIF7TWI Data Interrupt Flag
TWASIF6TWI Address/Stop Interrupt Flag
TWCH5TWI Clock Hold
TWRA4TWI Receive Acknowledge
TWC3TWI Collision
TWBE2TWI Bus Error
TWDIR1TWI Read/Write Direction
TWAS0TWI Address or Stop

TWSCRBTWI Slave Control Register B

Address
0x2C I/O 0x0C
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2TWAA
  7. 1TWCMD1
  8. 0TWCMD0
2 fields
FieldBitsWhat it does
TWAA2TWI Acknowledge Action
TWCMD1:0

TWSCRATWI Slave Control Register A

Address
0x2D I/O 0x0D
Reset
0x00
Access
read/write
  1. 7TWSHE
  2. 6–
  3. 5TWDIE
  4. 4TWASIE
  5. 3TWEN
  6. 2TWSIE
  7. 1TWPME
  8. 0TWSME
7 fields
FieldBitsWhat it does
TWSHE7TWI SDA Hold Time Enable
TWDIE5TWI Data Interrupt Enable
TWASIE4TWI Address/Stop Interrupt Enable
TWEN3Two-Wire Interface Enable
TWSIE2TWI Stop Interrupt Enable
TWPME1TWI Promiscuous Mode Enable
TWSME0TWI Smart Mode Enable

SPI Serial Peripheral Interface

SPDRSPI Data Register

Address
0x2E I/O 0x0E
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–

SPSRSPI Status Register

Address
0x2F I/O 0x0F
Reset
0x00
Access
read/write
  1. 7SPIF
  2. 6WCOL
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0SPI2X
3 fields
FieldBitsWhat it does
SPIF7SPI Interrupt Flag
WCOL6Write Collision Flag
SPI2X0Double SPI Speed Bit

SPCRSPI Control Register

Address
0x30 I/O 0x10
Reset
0x00
Access
read/write
  1. 7SPIE
  2. 6SPE
  3. 5DORD
  4. 4MSTR
  5. 3CPOL
  6. 2CPHA
  7. 1SPR1
  8. 0SPR0
7 fields
FieldBitsWhat it does
SPIE7SPI Interrupt Enable
SPE6SPI Enable
DORD5Data Order
MSTR4Master/Slave Select
CPOL3Clock polarity
CPHA2Clock Phase
SPR1:0SPI Clock Rate Selects
  • 0 fcl/4
  • 1 fcl/16
  • 2 fcl/64
  • 3 fcl/128

WDT Watchdog Timer

WDTCSRWatchdog Timer Control and Status Register

Address
0x31 I/O 0x11
Reset
0x00
Access
read/write
  1. 7WDIF
  2. 6WDIE
  3. 5WDP5
  4. 4–
  5. 3WDE
  6. 2WDP2
  7. 1WDP1
  8. 0WDP0
4 fields
FieldBitsWhat it does
WDIF7Watchdog Timer Interrupt Flag
WDIE6Watchdog Timer Interrupt Enable
WDP5,2,1,0Watchdog 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
WDE3Watch Dog Enable

CPU CPU Registers

NVMCSRNon-Volatile Memory Control and Status Register

Address
0x32 I/O 0x12
Reset
0x00
Access
read/write
  1. 7NVMBSY
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–
1 field
FieldBitsWhat it does
NVMBSY7Non-Volatile Memory Busy

NVMCMDNon-Volatile Memory Command

Address
0x33 I/O 0x13
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–

PRRPower Reduction Register

Address
0x35 I/O 0x15
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4PRTWI
  5. 3PRSPI
  6. 2PRTIM1
  7. 1PRTIM0
  8. 0PRADC
5 fields
FieldBitsWhat it does
PRTWI4Power Reduction TWI
PRSPI3Power Reduction Serial Peripheral Interface
PRTIM12Power Reduction Timer/Counter1
PRTIM01Power Reduction Timer/Counter0
PRADC0Power Reduction ADC

CLKPSRClock Prescale Register

Address
0x36 I/O 0x16
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3CLKPS3
  6. 2CLKPS2
  7. 1CLKPS1
  8. 0CLKPS0
1 field
FieldBitsWhat it does
CLKPS3:0Clock Prescaler Select Bits
  • 0 1
  • 1 2
  • 2 4
  • 3 8
  • 4 16
  • 5 32
  • 6 64
  • 7 128
  • 8 256

CLKMSRClock Main Settings Register

Address
0x37 I/O 0x17
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1CLKMS1
  8. 0CLKMS0
1 field
FieldBitsWhat it does
CLKMS1:0Clock Main Select Bits

OSCCALOscillator Calibration Value

Address
0x39 I/O 0x19
Reset
0x00
Access
read/write
  1. 7OSCCAL7
  2. 6OSCCAL6
  3. 5OSCCAL5
  4. 4OSCCAL4
  5. 3OSCCAL3
  6. 2OSCCAL2
  7. 1OSCCAL1
  8. 0OSCCAL0
1 field
FieldBitsWhat it does
OSCCAL7:0Oscillator Calibration

MCUCRMCU Control Register

Address
0x3A I/O 0x1A
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4BODS
  5. 3SM2
  6. 2SM1
  7. 1SM0
  8. 0SE
3 fields
FieldBitsWhat it does
BODS4BOD Sleep
SM3:1Sleep Mode
  • 0 Idle
  • 1 ADC noise reduction
  • 2 Power-down
  • 4 Standby
SE0Sleep Enable

RSTFLRReset Flag Register

Address
0x3B I/O 0x1B
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3WDRF
  6. 2–
  7. 1EXTRF
  8. 0PORF
3 fields
FieldBitsWhat it does
WDRF3Watchdog Reset Flag
EXTRF1External Reset Flag
PORF0Power-on Reset Flag

CCPConfiguration Change Protection

Address
0x3C I/O 0x1C
Reset
0x00
Access
read/write
  1. 7–
  2. 6–
  3. 5–
  4. 4–
  5. 3–
  6. 2–
  7. 1–
  8. 0–

SPStack Pointer

Address
0x3D I/O 0x1D
Reset
0x00BF
Access
read/write
Size
16-bit

SREGStatus Register

Address
0x3F I/O 0x1F
Reset
0x00
Access
read/write
  1. 7I
  2. 6T
  3. 5H
  4. 4S
  5. 3V
  6. 2N
  7. 1Z
  8. 0C
8 fields
FieldBitsWhat it does
I7Global Interrupt Enable
T6Bit Copy Storage
H5Half Carry Flag
S4Sign Bit
V3Two's Complement Overflow Flag
N2Negative Flag
Z1Zero Flag
C0Carry Flag