- •Features
- •Overview
- •Block Diagram
- •Pin Descriptions
- •Port A (PA2..PA0)
- •Port B (PB7..PB0)
- •Port D (PD6..PD0)
- •RESET
- •XTAL1
- •XTAL2
- •Resources
- •Code Examples
- •Disclaimer
- •AVR CPU Core
- •Introduction
- •Status Register
- •Stack Pointer
- •Erase
- •Write
- •I/O Memory
- •Clock Systems and their Distribution
- •CPU Clock – clkCPU
- •I/O Clock – clkI/O
- •Flash Clock – clkFLASH
- •Clock Sources
- •Crystal Oscillator
- •External Clock
- •Idle Mode
- •Power-down Mode
- •Standby Mode
- •Analog Comparator
- •Watchdog Timer
- •Port Pins
- •Resetting the AVR
- •Reset Sources
- •Power-on Reset
- •External Reset
- •Watchdog Reset
- •Watchdog Timer
- •Interrupts
- •I/O-Ports
- •Introduction
- •Configuring the Pin
- •Toggling the Pin
- •Reading the Pin Value
- •Alternate Port Functions
- •Register Description for I/O-Ports
- •8-bit Timer/Counter0 with PWM
- •Overview
- •Registers
- •Definitions
- •Counter Unit
- •Normal Mode
- •Fast PWM Mode
- •8-bit Timer/Counter Register Description
- •Timer/Counter0 and Timer/Counter1 Prescalers
- •Internal Clock Source
- •Prescaler Reset
- •External Clock Source
- •16-bit Timer/Counter1
- •Overview
- •Registers
- •Definitions
- •Compatibility
- •Counter Unit
- •Input Capture Unit
- •Noise Canceler
- •Force Output Compare
- •Normal Mode
- •Fast PWM Mode
- •16-bit Timer/Counter Register Description
- •USART
- •Overview
- •AVR USART vs. AVR UART – Compatibility
- •Clock Generation
- •External Clock
- •Frame Formats
- •Parity Bit Calculation
- •Parity Generator
- •Receiver Error Flags
- •Parity Checker
- •Disabling the Receiver
- •Using MPCM
- •Overview
- •Three-wire Mode
- •Two-wire Mode
- •4-bit Counter
- •12-bit Timer/Counter
- •Software Interrupt
- •Analog Comparator
- •Features
- •Overview
- •Physical Interface
- •Limitations of debugWIRE
- •debugWire Data Register – DWDR
- •Fuse Bits
- •Latching of Fuses
- •Signature Bytes
- •Calibration Byte
- •Page Size
- •Signal Names
- •Chip Erase
- •Reading the Flash
- •Reading the EEPROM
- •Electrical Characteristics
- •Absolute Maximum Ratings*
- •DC Characteristics
- •External Clock Drive Waveforms
- •Maximum Speed vs. VCC
- •Idle Supply Current
- •Pin Pull-up
- •Pin Driver Strength
- •Register Summary
- •Instruction Set Summary
- •Ordering Information
- •Packaging Information
- •Errata
- •ATtiny2313 Rev C
- •ATtiny2313 Rev B
- •ATtiny2313 Rev A
- •Changes from Rev. 2543H-02/05 to Rev. 2543I-04/06
- •Changes from Rev. 2543G-10/04 to Rev. 2543H-02/05
- •Changes from Rev. 2543F-08/04 to Rev. 2543G-10/04
- •Changes from Rev. 2543E-04/04 to Rev. 2543F-08/04
- •Changes from Rev. 2543D-03/04 to Rev. 2543E-04/04
- •Changes from Rev. 2543C-12/03 to Rev. 2543D-03/04
- •Changes from Rev. 2543B-09/03 to Rev. 2543C-12/03
- •Changes from Rev. 2543A-09/03 to Rev. 2543B-09/03
- •Table of Contents
ATtiny2313
Figure 16. MCU Start-up, RESET Extended Externally
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VPOT |
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VCC |
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VRST |
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RESET |
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tTOUT |
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TIME-OUT |
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INTERNAL |
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RESET |
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External Reset |
An External Reset is generated by a low level on the |
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pin. Reset pulses longer than the |
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RESET |
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minimum pulse width (see Table 15) will generate a reset, even if the clock is not running. |
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Shorter pulses are not guaranteed to generate a reset. When the applied signal reaches the |
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Reset Threshold Voltage – VRST – on its positive edge, the delay counter starts the MCU after |
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the Time-out period – tTOUT – has expired. |
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Figure 17. External Reset During Operation |
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CC |
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Brown-out Detection ATtiny2313 has an On-chip Brown-out Detection (BOD) circuit for monitoring the VCC level during operation by comparing it to a fixed trigger level. The trigger level for the BOD can be selected by the BODLEVEL Fuses. The trigger level has a hysteresis to ensure spike free Brown-out Detection. The hysteresis on the detection level should be interpreted as VBOT+ =
VBOT + VHYST/2 and VBOT- = VBOT - VHYST/2.
Table 16. BODLEVEL Fuse Coding(1)
BODLEVEL 2..0 Fuses |
Min VBOT |
Typ VBOT |
Max VBOT |
Units |
111 |
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BOD Disabled |
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110 |
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1.8 |
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101 |
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2.7 |
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V |
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100 |
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4.3 |
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35
2543L–AVR–08/10
Table 16. BODLEVEL Fuse Coding(1)
BODLEVEL 2..0 Fuses |
Min VBOT |
Typ VBOT |
Max VBOT |
Units |
011
010
Reserved
001
000
Note: 1. VBOT may be below nominal minimum operating voltage for some devices. For devices where this is the case, the device is tested down to VCC = VBOT during the production test. This guarantees that a Brown-Out Reset will occur before VCC drops to a voltage where correct operation of the microcontroller is no longer guaranteed. The test is performed using BODLEVEL = 110 for ATtiny2313V and BODLEVEL = 101 for ATtiny2313L.
Table 17. Brown-out Characteristics
Symbol |
Parameter |
Min |
Typ |
Max |
Units |
VHYST |
Brown-out Detector Hysteresis |
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50 |
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mV |
tBOD |
Min Pulse Width on Brown-out Reset |
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2 |
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ns |
When the BOD is enabled, and VCC decreases to a value below the trigger level (VBOT- in Figure 18), the Brown-out Reset is immediately activated. When VCC increases above the trigger level
(VBOT+ in Figure 18), the delay counter starts the MCU after the Time-out period tTOUT has expired.
The BOD circuit will only detect a drop in VCC if the voltage stays below the trigger level for longer than tBOD given in Table 15.
Figure 18. Brown-out Reset During Operation
VCC |
VBOT+ |
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VBOT- |
RESET
TIME-OUT |
tTOUT |
INTERNAL
RESET
36 ATtiny2313
2543L–AVR–08/10
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ATtiny2313 |
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Watchdog Reset |
When the Watchdog times out, it will generate a short reset pulse of one CK cycle duration. On |
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the falling edge of this pulse, the delay timer starts counting the Time-out period tTOUT. Refer to |
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page 44 for details on operation of the Watchdog Timer. |
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Figure 19. Watchdog Reset During Operation |
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CC |
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CK
MCU Status Register –
MCUSR
The MCU Status Register provides information on which reset source caused an MCU reset.
Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
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– |
– |
– |
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WDRF |
BORF |
EXTRF |
PORF |
MCUSR |
Read/Write |
R |
R |
R |
R |
R/W |
R/W |
R/W |
R/W |
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Initial Value |
0 |
0 |
0 |
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See Bit Description |
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• Bit 3 – WDRF: Watchdog Reset Flag
This bit is set if a Watchdog Reset occurs. The bit is reset by a Power-on Reset, or by writing a logic zero to the flag.
• Bit 2 – BORF: Brown-out Reset Flag
This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by writing a logic zero to the flag.
• Bit 1 – EXTRF: External Reset Flag
This bit is set if an External Reset occurs. The bit is reset by a Power-on Reset, or by writing a logic zero to the flag.
• Bit 0 – PORF: Power-on Reset Flag
This bit is set if a Power-on Reset occurs. The bit is reset only by writing a logic zero to the flag.
To make use of the Reset flags to identify a reset condition, the user should read and then reset the MCUSR as early as possible in the program. If the register is cleared before another reset occurs, the source of the reset can be found by examining the reset flags.
37
2543L–AVR–08/10
Internal Voltage |
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ATtiny2313 features an internal bandgap reference. This reference is used for Brown-out Detec- |
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Reference |
tion, and it can be used as an input to the Analog Comparator. |
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Voltage Reference |
The voltage reference has a start-up time that may influence the way it should be used. The |
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Enable Signals and |
start-up time is given in Table 18. To save power, the reference is not always turned on. The ref- |
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Start-up Time |
erence is on during the following situations: |
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1. When the BOD is enabled (by programming the BODLEVEL [2..0] Fuse). |
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2. When the bandgap reference is connected to the Analog Comparator (by setting the |
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ACBG bit in ACSR). |
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Thus, when the BOD is not enabled, after setting the ACBG bit, the user must always allow the |
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reference to start up before the output from the Analog Comparator is used. To reduce power |
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consumption in Power-down mode, the user can avoid the three conditions above to ensure that |
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the reference is turned off before entering Power-down mode. |
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Table 18. Internal Voltage Reference Characteristics(1) |
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Symbol |
Parameter |
Condition |
Min |
Typ |
Max |
Units |
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VBG |
Bandgap reference voltage |
VCC = 2.7V, |
1.0 |
1.1 |
1.2 |
V |
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TA = 25°C |
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tBG |
Bandgap reference start-up time |
VCC = 2.7V, |
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40 |
70 |
µs |
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TA = 25°C |
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IBG |
Bandgap reference current |
VCC = 2.7V, |
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µA |
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consumption |
TA = 25°C |
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Note: 1. |
Values are guidelines only. Actual values are TBD. |
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38 ATtiny2313
2543L–AVR–08/10