Atmel ATtiny13A User Manual

40
8126F–AVR–05/12
ATtiny13A
The following code example shows one assembly and one C function for turning off the Watch-
dog Timer. The example assumes that interrupts are controlled (e.g. by disabling interrupts
globally) so that no interrupts will occur during the execution of these functions.
Note: See “Code Examples” on page 6.
If the Watchdog is accidentally enabled, for example by a runaway pointer or brown-out condi-
tion, the device will be reset and the Watchdog Timer will stay enabled. If the code is not set up
to handle the Watchdog, this might lead to an eternal loop of time-out resets. To avoid this situa-
Assembly Code Example
WDT_off:
; Turn off global interrupt
cli
; Reset Watchdog Timer
wdr
; Clear WDRF in MCUSR
in r16, MCUSR
andi r16, (0xff - (1<<WDRF))
out MCUSR, r16
; Write logical one to WDCE and WDE
; Keep old prescaler setting to prevent unintentional time-out
in r16, WDTCR
ori r16, (1<<WDCE) | (1<<WDE)
out WDTCR, r16
; Turn off WDT
ldi r16, (0<<WDE)
out WDTCR, r16
; Turn on global interrupt
sei
ret
C Code Example
void WDT_off(void)
{
__disable_interrupt();
__watchdog_reset();
/* Clear WDRF in MCUSR */
MCUSR &= ~(1<<WDRF);
/* Write logical one to WDCE and WDE */
/* Keep old prescaler setting to prevent unintentional time-out */
WDTCR |= (1<<WDCE) | (1<<WDE);
/* Turn off WDT */
WDTCR = 0x00;
__enable_interrupt();
}

Atmel ATtiny13A Specifications

General

Brand	Atmel
Model	ATtiny13A
Category	Microcontrollers
Language	English

Summary

Pin Configurations

ATtiny13A CPU Core

CPU Core Architectural Overview

ALU and Status Register

Description of the Arithmetic Logic Unit (ALU) and the Status Register.

General Purpose Register File

Reset and Interrupt Handling

How the microcontroller handles resets and interrupts for system control.

ATtiny13A Memories

Flash Program Memory

Details on the In-System Reprogrammable Flash Program Memory.

SRAM and EEPROM Data Memory

Description of SRAM and EEPROM data memory organization and features.

System Clock and Clock Options

Clock Systems and Distribution

Clock Sources and Prescaler

Details on available clock sources and the system clock prescaler.

Power Management and Sleep Modes

Sleep Modes Overview

Explanation of the different sleep modes available for power saving.

Software BOD Disable and Power Reduction

Methods for software control of Brown-out Detector and power reduction.

System Control and Reset

Resetting the AVR and Reset Sources

Details on resetting the AVR and the different reset sources.

Internal Voltage Reference and Watchdog Timer

Interrupts

Interrupt Vectors and External Interrupts

Details on interrupt vectors and external interrupt sources.

Interrupt Register Description

I/O Ports

I/O Ports Overview and General Digital I/O

Overview of I/O ports and their use as general digital inputs/outputs.

Alternate Port Functions and Register Description

8-bit Timer/Counter0 with PWM

Timer/Counter Features and Overview

Features and overview of the 8-bit Timer/Counter0 module with PWM support.

Clock Sources, Counter Unit, and Output Compare Unit

Details on clock sources, counter unit, and output compare functionality.

Compare Match Output Unit, Modes of Operation, and Timing Diagrams

How compare matches affect output, operational modes, and timing.

Timer/Counter Prescaler

Prescaler Overview, Reset, and External Clock

Analog Comparator

Analog Comparator Multiplexed Input and Register Description

Details on multiplexed inputs and register descriptions for the analog comparator.

Analog to Digital Converter (ADC)

ADC Features and Overview

ADC Operation and Conversion Start

Description of ADC operation and how to initiate a conversion.

ADC Prescaling, Timing, and Channel Selection

ADC Noise Canceling, Input, and Accuracy

ADC Conversion Result and Register Description

debugWIRE On-chip Debug System

debugWIRE Features, Overview, and Interface

Features, overview, and physical interface of the debugwire system.

Software Breakpoints, Limitations, and Registers

Self-Programming the Flash

Flash Programming Procedures

Programming Considerations and Time

Memory Programming

Program and Data Memory Lock Bits

Fuse Bytes

Calibration Bytes

Electrical Characteristics

Absolute Maximum Ratings and DC Characteristics

Defines the absolute maximum operating conditions and DC electrical parameters.

Speed, Clock, and System/Reset Characteristics

Analog Comparator and ADC Characteristics

Serial and High-voltage Programming Characteristics

Register Summary

Instruction Set Summary