ATMEGA64A-MN Atmel, ATMEGA64A-MN Datasheet - Page 115

• Manufacturer Part Number: ATMEGA64A-MN
• Description: IC MCU AVR 64K FLASH 8QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA64A-MN

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8160C–AVR–07/09
It is important to notice that accessing 16-bit registers are atomic operations. If an interrupt
occurs between the two instructions accessing the 16-bit register, and the interrupt code
updates the temporary register by accessing the same or any other of the 16-bit timer registers,
then the result of the access outside the interrupt will be corrupted. Therefore, when both the
main code and the interrupt code update the temporary register, the main code must disable the
interrupts during the 16-bit access.
The following code examples show how to do an atomic read of the TCNTn Register contents.
Reading any of the OCRnA/B/C or ICRn Registers can be done by using the same principle.
Note:
Assembly Code Example
C Code Example
TIM16_ReadTCNTn:
unsigned int TIM16_ReadTCNTn( void )
{
}
; Save global interrupt flag
in
; Disable interrupts
cli
; Read TCNTn into r17:r16
in
in
; Restore global interrupt flag
out SREG,r18
ret
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;
1. See “About Code Examples” on page 8.
r18,SREG
r16,TCNTnL
r17,TCNTnH
The assembly code example returns the TCNTn value in the r17:r16 register pair.
(1)
(1)
ATmega64A
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