- •Features
- •1. Pin Configurations
- •1.1 Pin Descriptions
- •1.1.3 Port B (PB5:PB0)
- •1.1.4 RESET
- •2. Overview
- •2.1 Block Diagram
- •3. General Information
- •3.1 Resources
- •3.2 Code Examples
- •3.3 Data Retention
- •4. CPU Core
- •4.1 Architectural Overview
- •4.2 ALU – Arithmetic Logic Unit
- •4.3 Status Register
- •4.3.1 SREG – Status Register
- •4.4 General Purpose Register File
- •4.5 Stack Pointer
- •4.5.1 SPL - Stack Pointer Low.
- •4.6 Instruction Execution Timing
- •4.7 Reset and Interrupt Handling
- •4.7.1 Interrupt Response Time
- •5. Memories
- •5.2 SRAM Data Memory
- •5.2.1 Data Memory Access Times
- •5.3 EEPROM Data Memory
- •5.3.1 EEPROM Read/Write Access
- •5.3.2 Atomic Byte Programming
- •5.3.3 Split Byte Programming
- •5.3.4 Erase
- •5.3.5 Write
- •5.3.6 Preventing EEPROM Corruption
- •5.4 I/O Memory
- •5.5 Register Description
- •5.5.1 EEARL – EEPROM Address Register
- •5.5.2 EEDR – EEPROM Data Register
- •5.5.3 EECR – EEPROM Control Register
- •6. System Clock and Clock Options
- •6.1 Clock Systems and their Distribution
- •6.2 Clock Sources
- •6.2.1 External Clock
- •6.2.2 Calibrated Internal 4.8/9.6 MHz Oscillator
- •6.2.3 Internal 128 kHz Oscillator
- •6.2.4 Default Clock Source
- •6.3 System Clock Prescaler
- •6.3.1 Switching Time
- •6.4 Register Description
- •6.4.1 OSCCAL – Oscillator Calibration Register
- •6.4.2 CLKPR – Clock Prescale Register
- •7. Power Management and Sleep Modes
- •7.1 Sleep Modes
- •7.1.1 Idle Mode
- •7.1.2 ADC Noise Reduction Mode
- •7.2 Minimizing Power Consumption
- •7.2.1 Analog to Digital Converter
- •7.2.2 Analog Comparator
- •7.2.4 Internal Voltage Reference
- •7.2.5 Watchdog Timer
- •7.2.6 Port Pins
- •7.3 Register Description
- •7.3.1 MCUCR – MCU Control Register
- •8. System Control and Reset
- •8.0.1 Resetting the AVR
- •8.1 Reset Sources
- •8.1.2 External Reset
- •8.1.4 Watchdog Reset
- •8.2 Internal Voltage Reference
- •8.3 Watchdog Timer
- •8.4 Register Description
- •8.4.1 MCUSR – MCU Status Register
- •8.4.2 WDTCR – Watchdog Timer Control Register
- •9. Interrupts
- •9.1 Interrupt Vectors
- •9.2 External Interrupts
- •9.2.1 Low Level Interrupt
- •9.2.2 Pin Change Interrupt Timing
- •9.3 Register Description
- •9.3.1 MCUCR – MCU Control Register
- •9.3.2 GIMSK – General Interrupt Mask Register
- •9.3.3 GIFR – General Interrupt Flag Register
- •9.3.4 PCMSK – Pin Change Mask Register
- •10. I/O Ports
- •10.1 Overview
- •10.2 Ports as General Digital I/O
- •10.2.1 Configuring the Pin
- •10.2.2 Toggling the Pin
- •10.2.3 Switching Between Input and Output
- •10.2.4 Reading the Pin Value
- •10.2.5 Digital Input Enable and Sleep Modes
- •10.2.6 Unconnected Pins
- •10.3 Alternate Port Functions
- •10.3.1 Alternate Functions of Port B
- •10.4 Register Description
- •10.4.1 MCUCR – MCU Control Register
- •10.4.2 PORTB – Port B Data Register
- •10.4.3 DDRB – Port B Data Direction Register
- •10.4.4 PINB – Port B Input Pins Address
- •11. 8-bit Timer/Counter0 with PWM
- •11.1 Features
- •11.2 Overview
- •11.2.1 Registers
- •11.2.2 Definitions
- •11.3 Timer/Counter Clock Sources
- •11.4 Counter Unit
- •11.5 Output Compare Unit
- •11.5.1 Force Output Compare
- •11.5.2 Compare Match Blocking by TCNT0 Write
- •11.5.3 Using the Output Compare Unit
- •11.6 Compare Match Output Unit
- •11.6.1 Compare Output Mode and Waveform Generation
- •11.7 Modes of Operation
- •11.7.1 Normal Mode
- •11.7.2 Clear Timer on Compare Match (CTC) Mode
- •11.7.3 Fast PWM Mode
- •11.7.4 Phase Correct PWM Mode
- •11.8 Timer/Counter Timing Diagrams
- •11.9 Register Description
- •11.9.1 TCCR0A – Timer/Counter Control Register A
- •11.9.2 TCCR0B – Timer/Counter Control Register B
- •11.9.3 TCNT0 – Timer/Counter Register
- •11.9.4 OCR0A – Output Compare Register A
- •11.9.5 OCR0B – Output Compare Register B
- •11.9.6 TIMSK0 – Timer/Counter Interrupt Mask Register
- •11.9.7 TIFR0 – Timer/Counter 0 Interrupt Flag Register
- •12. Timer/Counter Prescaler
- •12.1 Overview
- •12.2 Prescaler Reset
- •12.3 External Clock Source
- •12.4 Register Description.
- •12.4.1 GTCCR – General Timer/Counter Control Register
- •13. Analog Comparator
- •13.1 Analog Comparator Multiplexed Input
- •13.2 Register Description
- •13.2.1 ADCSRB – ADC Control and Status Register
- •13.2.2 ACSR– Analog Comparator Control and Status Register
- •13.2.3 DIDR0 – Digital Input Disable Register 0
- •14. Analog to Digital Converter
- •14.1 Features
- •14.2 Overview
- •14.3 Operation
- •14.4 Starting a Conversion
- •14.5 Prescaling and Conversion Timing
- •14.6 Changing Channel or Reference Selection
- •14.6.1 ADC Input Channels
- •14.6.2 ADC Voltage Reference
- •14.7 ADC Noise Canceler
- •14.8 Analog Input Circuitry
- •14.9 Analog Noise Canceling Techniques
- •14.10 ADC Accuracy Definitions
- •14.11 ADC Conversion Result
- •14.12 Register Description
- •14.12.1 ADMUX – ADC Multiplexer Selection Register
- •14.12.2 ADCSRA – ADC Control and Status Register A
- •14.12.3 ADCL and ADCH – The ADC Data Register
- •14.12.3.1 ADLAR = 0
- •14.12.3.2 ADLAR = 1
- •14.12.4 ADCSRB – ADC Control and Status Register B
- •14.12.5 DIDR0 – Digital Input Disable Register 0
- •15. debugWIRE On-chip Debug System
- •15.1 Features
- •15.2 Overview
- •15.3 Physical Interface
- •15.4 Software Break Points
- •15.5 Limitations of debugWIRE
- •15.6 Register Description
- •16. Self-Programming the Flash
- •16.1 Performing Page Erase by SPM
- •16.2 Filling the Temporary Buffer (Page Loading)
- •16.3 Performing a Page Write
- •16.5 EEPROM Write Prevents Writing to SPMCSR
- •16.6 Reading Fuse and Lock Bits from Firmware
- •16.6.1 Reading Lock Bits from Firmware
- •16.6.2 Reading Fuse Bits from Firmware
- •16.7 Preventing Flash Corruption
- •16.8 Programming Time for Flash when Using SPM
- •16.9 Register Description
- •16.9.1 SPMCSR – Store Program Memory Control and Status Register
- •17. Memory Programming
- •17.1 Program And Data Memory Lock Bits
- •17.2 Fuse Bytes
- •17.2.1 Latching of Fuses
- •17.3 Calibration Bytes
- •17.4 Signature Bytes
- •17.5 Page Size
- •17.6 Serial Programming
- •17.6.1 Serial Programming Algorithm
- •17.6.2 Serial Programming Instruction set
- •17.7 High-Voltage Serial Programming
- •17.8 Considerations for Efficient Programming
- •17.8.1 Chip Erase
- •17.8.2 Programming the Flash
- •17.8.3 Programming the EEPROM
- •17.8.4 Reading the Flash
- •17.8.5 Reading the EEPROM
- •17.8.6 Programming and Reading the Fuse and Lock Bits
- •17.8.7 Reading the Signature Bytes and Calibration Byte
- •18. Electrical Characteristics
- •18.1 Absolute Maximum Ratings*
- •18.2 DC Characteristics
- •18.3 Speed Grades
- •18.4 Clock Characteristics
- •18.4.1 Calibrated Internal RC Oscillator Accuracy
- •18.4.2 External Clock Drive
- •18.5 System and Reset Characteristics
- •18.6 Analog Comparator Characteristics
- •18.7 ADC Characteristics
- •18.8 Serial Programming Characteristics
- •18.9 High-voltage Serial Programming Characteristics
- •19. Typical Characteristics
- •19.1 Active Supply Current
- •19.2 Idle Supply Current
- •19.5 Pin Driver Strength
- •19.6 Pin Thresholds and Hysteresis
- •19.7 BOD Thresholds and Analog Comparator Offset
- •19.8 Internal Oscillator Speed
- •19.9 Current Consumption of Peripheral Units
- •19.10 Current Consumption in Reset and Reset Pulse width
- •20. Register Summary
- •21. Instruction Set Summary
- •22. Ordering Information
- •23. Packaging Information
- •24. Errata
- •24.1 ATtiny13 Rev. D
- •24.2 ATtiny13 Rev. C
- •24.3 ATtiny13 Rev. B
- •24.3.1 Wrong values read after Erase Only operation
- •24.3.2 High Voltage Serial Programming Flash, EEPROM, Fuse and Lock Bits may fail
- •24.3.3 Device may lock for further programming
- •24.3.5 Watchdog Timer Interrupt disabled
- •24.3.6 EEPROM can not be written below 1.9 Volt
- •24.4 ATtiny13 Rev. A
- •25. Datasheet Revision History
- •Table of Contents
ATtiny13
Note that enabling the alternate function of some of the port pins does not affect the use of the other pins in the port as general digital I/O.
10.2Ports as General Digital I/O
The ports are bi-directional I/O ports with optional internal pull-ups. Figure 10-2 on page 49 shows a functional description of one I/O-port pin, here generically called Pxn.
Figure 10-2. |
General Digital I/O(1) |
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PUD |
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Q |
D |
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DDxn |
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Q CLR |
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RESET |
WDx |
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RDx |
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Q |
D |
1 |
BUS |
Pxn |
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DATA |
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PORTxn |
0 |
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Q CLR |
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RESET |
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WPx |
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WRx |
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SLEEP |
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RRx |
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SYNCHRONIZER |
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RPx |
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D |
Q |
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Q |
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PINxn |
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L |
Q |
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Q |
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clk I/O |
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PUD: |
PULLUP DISABLE |
WDx: |
WRITE DDRx |
RDx: |
READ DDRx |
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SLEEP: |
SLEEP CONTROL |
WRx: |
WRITE PORTx |
clkI/O: |
I/O CLOCK |
RRx: |
READ PORTx REGISTER |
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RPx: |
READ PORTx PIN |
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WPx: |
WRITE PINx REGISTER |
Note: 1. WRx, WPx, WDx, RRx, RPx, and RDx are common to all pins within the same port. clkI/O,
SLEEP, and PUD are common to all ports.
10.2.1Configuring the Pin
Each port pin consists of three register bits: DDxn, PORTxn, and PINxn. As shown in “Register Description” on page 56, the DDxn bits are accessed at the DDRx I/O address, the PORTxn bits at the PORTx I/O address, and the PINxn bits at the PINx I/O address.
The DDxn bit in the DDRx Register selects the direction of this pin. If DDxn is written logic one, Pxn is configured as an output pin. If DDxn is written logic zero, Pxn is configured as an input pin.
49
2535J–AVR–08/10
If PORTxn is written logic one when the pin is configured as an input pin, the pull-up resistor is activated. To switch the pull-up resistor off, PORTxn has to be written logic zero or the pin has to be configured as an output pin. The port pins are tri-stated when reset condition becomes active, even if no clocks are running.
If PORTxn is written logic one when the pin is configured as an output pin, the port pin is driven high (one). If PORTxn is written logic zero when the pin is configured as an output pin, the port pin is driven low (zero).
10.2.2Toggling the Pin
Writing a logic one to PINxn toggles the value of PORTxn, independent on the value of DDRxn.
Note that the SBI instruction can be used to toggle one single bit in a port.
10.2.3Switching Between Input and Output
When switching between tri-state ({DDxn, PORTxn} = 0b00) and output high ({DDxn, PORTxn} = 0b11), an intermediate state with either pull-up enabled {DDxn, PORTxn} = 0b01) or output low ({DDxn, PORTxn} = 0b10) must occur. Normally, the pull-up enabled state is fully acceptable, as a high-impedant environment will not notice the difference between a strong high driver and a pull-up. If this is not the case, the PUD bit in the MCUCR Register can be set to disable all pull-ups in all ports.
Switching between input with pull-up and output low generates the same problem. The user must use either the tri-state ({DDxn, PORTxn} = 0b00) or the output high state ({DDxn, PORTxn} = 0b10) as an intermediate step.
Table 10-1 summarizes the control signals for the pin value.
Table 10-1. Port Pin Configurations
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PUD |
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DDxn |
PORTxn |
(in MCUCR) |
I/O |
Pull-up |
Comment |
0 |
0 |
X |
Input |
No |
Tri-state (Hi-Z) |
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0 |
1 |
0 |
Input |
Yes |
Pxn will source current if ext. pulled low. |
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0 |
1 |
1 |
Input |
No |
Tri-state (Hi-Z) |
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1 |
0 |
X |
Output |
No |
Output Low (Sink) |
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1 |
1 |
X |
Output |
No |
Output High (Source) |
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10.2.4Reading the Pin Value
Independent of the setting of Data Direction bit DDxn, the port pin can be read through the PINxn Register bit. As shown in Figure 10-2 on page 49, the PINxn Register bit and the preceding latch constitute a synchronizer. This is needed to avoid metastability if the physical pin changes value near the edge of the internal clock, but it also introduces a delay. Figure 10-3 on page 51 shows a timing diagram of the synchronization when reading an externally applied pin
value. The maximum and minimum propagation delays are denoted tpd,max and tpd,min respectively.
50 ATtiny13
2535J–AVR–08/10
ATtiny13
Figure 10-3. Synchronization when Reading an Externally Applied Pin value
SYSTEM CLK
INSTRUCTIONS
SYNC LATCH
PINxn
XXX |
XXX |
in r17, PINx |
r17 |
0x00 |
0xFF |
tpd, max
tpd, min
Consider the clock period starting shortly after the first falling edge of the system clock. The latch is closed when the clock is low, and goes transparent when the clock is high, as indicated by the shaded region of the “SYNC LATCH” signal. The signal value is latched when the system clock goes low. It is clocked into the PINxn Register at the succeeding positive clock edge. As indicated by the two arrows tpd,max and tpd,min, a single signal transition on the pin will be delayed between ½ and 1½ system clock period depending upon the time of assertion.
When reading back a software assigned pin value, a nop instruction must be inserted as indicated in Figure 10-4 on page 51. The out instruction sets the “SYNC LATCH” signal at the positive edge of the clock. In this case, the delay tpd through the synchronizer is one system clock period.
Figure 10-4. Synchronization when Reading a Software Assigned Pin Value
SYSTEM CLK
r16 |
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0xFF |
INSTRUCTIONS |
out PORTx, r16 |
nop |
in r17, PINx |
SYNC LATCH
PINxn
r17 |
0x00 |
0xFF |
tpd
51
2535J–AVR–08/10
The following code example shows how to set port B pins 0 and 1 high, 2 and 3 low, and define the port pins from 4 to 5 as input with a pull-up assigned to port pin 4. The resulting pin values are read back again, but as previously discussed, a nop instruction is included to be able to read back the value recently assigned to some of the pins.
Assembly Code Example(1)
...
;Define pull-ups and set outputs high
;Define directions for port pins
ldi r16,(1<<PB4)|(1<<PB1)|(1<<PB0)
ldi r17,(1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0) out PORTB,r16
out DDRB,r17
; Insert nop for synchronization
nop
; Read port pins in r16,PINB
...
C Code Example
unsigned char i;
...
/* Define pull-ups and set outputs high */ /* Define directions for port pins */ PORTB = (1<<PB4)|(1<<PB1)|(1<<PB0);
DDRB = (1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0); /* Insert nop for synchronization*/ __no_operation();
/* Read port pins */ i = PINB;
...
Note: 1. For the assembly program, two temporary registers are used to minimize the time from pullups are set on pins 0, 1 and 4, until the direction bits are correctly set, defining bit 2 and 3 as low and redefining bits 0 and 1 as strong high drivers.
10.2.5Digital Input Enable and Sleep Modes
As shown in Figure 10-2 on page 49, the digital input signal can be clamped to ground at the input of the schmitt-trigger. The signal denoted SLEEP in the figure, is set by the MCU Sleep Controller in Power-down mode, Power-save mode, and Standby mode to avoid high power consumption if some input signals are left floating, or have an analog signal level close to VCC/2.
SLEEP is overridden for port pins enabled as external interrupt pins. If the external interrupt request is not enabled, SLEEP is active also for these pins. SLEEP is also overridden by various other alternate functions as described in “Alternate Port Functions” on page 53.
If a logic high level (“one”) is present on an asynchronous external interrupt pin configured as “Interrupt on Rising Edge, Falling Edge, or Any Logic Change on Pin” while the external interrupt is not enabled, the corresponding External Interrupt Flag will be set when resuming from the
52 ATtiny13
2535J–AVR–08/10