ATMEGA128A-ANR Atmel, ATMEGA128A-ANR Datasheet - Page 37

• Manufacturer Part Number: ATMEGA128A-ANR
• Description: IC MCU AVR 128K FLASH 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA128A-ANR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 128KB (64K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 4K 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: 64-TQFP
• Core: AVR8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8. System Clock and Clock Options
8.1
8.1.1
8.1.2
8151H–AVR–02/11
Clock Systems and their Distribution
CPU Clock – clk
I/O Clock – clk
I/O
Figure 8-1
need not be active at a given time. In order to reduce power consumption, the clocks to modules
not being used can be halted by using different sleep modes, as described in
ment and Sleep Modes” on page
Figure 8-1.
The CPU clock is routed to parts of the system concerned with operation of the Atmel
core. Examples of such modules are the General Purpose Register File, the Status Register and
the data memory holding the Stack Pointer. Halting the CPU clock inhibits the core from per-
forming general operations and calculations.
The I/O clock is used by the majority of the I/O modules, like Timer/Counters, SPI, and USART.’
The I/O clock is also used by the External Interrupt module, but note that some external inter-
rupts are detected by asynchronous logic, allowing such interrupts to be detected even if the I/O
clock is halted. Also note that address recognition in the TWI module is carried out asynchro-
nously when clk
CPU
Asynchronous
Timer/Counter
Timer/Counter
Oscillator
presents the principal clock systems in the AVR and their distribution. All of the clocks
Clock Distribution
I/O
is halted, enabling TWI address reception in all sleep modes.
External RC
General I/O
Oscillator
modules
clk
clk
ASY
I/O
46. The clock systems are detailed below.
External clock
Control Unit
AVR Clock
Multiplexer
ADC
Clock
clk
Source clock
ADC
Reset Logic
CPU Core
clk
Oscillator
clk
Crystal
CPU
FLASH
Watchdog clock
Crystal Oscillator
Low-Frequency
RAM
Watchdog Timer
Watchdog
Oscillator
ATmega128A
“Power Manage-
Flash and
EEPROM
Calibrated RC
Oscillator
®
AVR
37
®