ATMEGA103L-4AC Atmel, ATMEGA103L-4AC Datasheet - Page 67

• Manufacturer Part Number: ATMEGA103L-4AC
• Description: IC MCU 128K 4MHZ A/D LV 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA103L-4AC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 4MHz
• Connectivity: SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 32
• 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 ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 64-TQFP, 64-VQFP
• For Use With: ATSTK501 - ADAPTER KIT FOR 64PIN AVR MCU
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

0945I–AVR–02/07
Figure 41. UART Transmitter
On the baud rate clock following the transfer operation to the Shift Register, the start bit
is shifted out on the TXD pin, followed by the data, LSB first. When the stop bit has been
shifted out, the Shift Register is loaded if any new data has been written to the UDR dur-
ing the transmission. During loading, UDRE is set. If there is no new data in the UDR
Register to send when the stop bit is shifted out, the UDRE Flag will remain set. In this
case, after the stop bit has been present on TXD for one bit length, the TX Complete
Flag (TXC) in USR is set.
The TXEN bit in UCR enables the UART Transmitter when set (one). When this bit is
cleared (zero), the PE1 pin can be used for general I/O. When TXEN is set, the UART
Transmitter will be connected to PE1, which is forced to be an output pin regardless of
the setting of the DDE1 bit in DDRE.
XTAL
CONTROL LOGIC
GENERATOR
BAUD RATE
STORE UDR
SHIFT ENABLE
BAUD x 16
IDLE
DATA BUS
REGISTER (UCR)
UART CONTROL
/16
BAUD
DATA BUS
REGISTER (UDR)
SHIFT REGISTER
UART I/O DATA
10(11)-BIT TX
TXC
IRQ
REGISTER (USR)
UART STATUS
ATmega103(L)
UDRE
IRQ
1
PIN CONTROL
LOGIC
TXD
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