Atmel ATmega32M1 User Manual

111
7647H–AVR–03/12
Atmel ATmega16/32/64/M1/C1
The following code examples show how to do an atomic read of the TCNTn Register contents.
Reading any of the OCRnx or ICRn Registers can be done by using the same principle.
Note: 1. The example code assumes that the part specific header file is included.
For I/O Registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”, and “SBI”
instructions must be replaced with instructions that allow access to extended I/O. Typically
“LDS” and “STS” combined with “SBRS”, “SBRC”, “SBR”, and “CBR”.
The assembly code example returns the TCNTn value in the r17:r16 register pair.
Assembly Code Example
(1)
TIM16_ReadTCNTn:
; Save global interrupt flag
in r18,SREG
; Disable interrupts
cli
; Read TCNTn into r17:r16
in r16,TCNTnL
in r17,TCNTnH
; Restore global interrupt flag
out SREG,r18
ret
C Code Example
(1)
unsigned int TIM16_ReadTCNTn( void )
{
unsigned char sreg;
unsigned int i;
/* Save global interrupt flag */
sreg = SREG;
/* Disable interrupts */
_CLI();
/* Read TCNTn into i */
i = TCNTn;
/* Restore global interrupt flag */
SREG = sreg;
return i;
}

Atmel ATmega32M1 Specifications

General

Architecture	8-bit AVR
Flash Memory	32 KB
SRAM	2 KB
EEPROM	1 KB
Clock Speed	16 MHz
GPIO Pins	32
I/O Pins	32
ADC Channels	8
ADC Resolution	10-bit
UART	1
USART	1
SPI	1
I2C	1
PWM Channels	6
CAN	1
Operating Voltage	2.7V - 5.5V
Operating Temperature	-40°C to +85°C
Temperature Range	-40°C to +85°C
Package	44-TQFP, 44-QFN

Summary

Features

AVR CPU Core

Reset and Interrupt Handling

Explanation of interrupt sources, vectors, priority levels, and behavior during interrupt execution.

System Clock

System Clock Prescaler

Details on the CLKPR register for dividing the system clock to reduce power consumption and affect peripheral frequencies.

Power Management and Sleep Modes

8-bit Timer/Counter0 with PWM

Modes of Operation

Detailed explanation of Normal, CTC, and various PWM modes for Timer/Counter0 operation.

Controller Area Network - CAN

CAN Protocol

Explanation of the CAN protocol principles, standards, and message transmission priorities.

Error Management

Description of error detection mechanisms (message and bit level) and fault confinement states.

Analog to Digital Converter - ADC

Features

List of ADC capabilities including resolution, accuracy, conversion time, input channels, and reference voltages.

Starting a Conversion

Procedures for initiating ADC conversions, including single conversion and auto-triggering modes.

debugWIRE On-chip Debug System

Features

Overview of debugWIRE capabilities including program flow control, real-time operation, and symbolic debugging.

Boot Loader Support – Read-While-Write Self-Programming ATmega16/32/64/M1/C1

Self-Programming the Flash

Procedures and considerations for programming the Flash memory using the SPM instruction.

Memory Programming

Program And Data Memory Lock Bits

Fuse Bits

Electrical Characteristics

Absolute Maximum Ratings*

Critical voltage, current, and temperature limits that must not be exceeded for device reliability.

DC Characteristics

Instruction Set Summary

Register Summary