ATMEGA128-16MC Atmel, ATMEGA128-16MC Datasheet - Page 210

• Manufacturer Part Number: ATMEGA128-16MC
• Description: IC AVR MCU 128K 16MHZ COM 64-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA128-16MC

• 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): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 64-MLF®, 64-QFN
• For Use With: ATAVRISP2 - PROGRAMMER AVR IN SYSTEMATSTK501 - ADAPTER KIT FOR 64PIN AVR MCU
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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ATmega128
Even though this example is simple, it shows the principles involved in all TWI transmissions.
These can be summarized as follows:
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•
•
In the following an assembly and C implementation of the example is given. Note that the code
below assumes that several definitions have been made for example by using include-files.
When the TWI has finished an operation and expects application response, the TWINT flag
is set. The SCL line is pulled low until TWINT is cleared.
When the TWINT flag is set, the user must update all TWI Registers with the value relevant
for the next TWI bus cycle. As an example, TWDR must be loaded with the value to be
transmitted in the next bus cycle.
After all TWI Register updates and other pending application software tasks have been
completed, TWCR is written. When writing TWCR, the TWINT bit should be set. Writing a
one to TWINT clears the flag. The TWI will then commence executing whatever operation
was specified by the TWCR setting.
2467V–AVR–02/11