ATMEGA16-16MU Atmel, ATMEGA16-16MU Datasheet - Page 157

• Manufacturer Part Number: ATMEGA16-16MU
• Description: IC AVR MCU 16K 16MHZ 5V 44-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA16-16MU

• 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: 32
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-VQFN Exposed Pad
• Cpu Family: ATmega
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 16MHz
• Interface Type: JTAG/SPI/UART
• Total Internal Ram Size: 1KB
• # I/os (max): 32
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 4.5V
• On-chip Adc: 8-chx10-bit
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 44
• Package Type: MLF
• Processor Series: ATMEGA16x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 1 KB
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 4.5 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• Package: 44MLF
• Family Name: ATmega
• Maximum Speed: 16 MHz
• Controller Family/series: AVR MEGA
• No. Of I/o's: 32
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 1KB
• Cpu Speed: 16MHz
• Rohs Compliant: Yes
• For Use With: ATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFPATSTK600 - DEV KIT FOR AVR/AVR32770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRISP2 - PROGRAMMER AVR IN SYSTEMATJTAGICE2 - AVR ON-CHIP D-BUG SYSTEMATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Disabling the Receiver In contrast to the Transmitter, disabling of the Receiver will be immediate. Data from ongoing
Flushing the Receive
Buffer
Asynchronous
Data Reception
Asynchronous Clock
Recovery
2466T–AVR–07/10
receptions will therefore be lost. When disabled (that is, the RXEN is set to zero) the Receiver
will no longer override the normal function of the RxD port pin. The receiver buffer FIFO will be
flushed when the receiver is disabled. Remaining data in the buffer will be lost
The receiver buffer FIFO will be flushed when the Receiver is disabled, that is, the buffer will be
emptied of its contents. Unread data will be lost. If the buffer has to be flushed during normal
operation, due to for instance an error condition, read the UDR I/O location until the RXC Flag is
cleared. The following code example shows how to flush the receive buffer.
Note:
The USART includes a clock recovery and a data recovery unit for handling asynchronous data
reception. The clock recovery logic is used for synchronizing the internally generated baud rate
clock to the incoming asynchronous serial frames at the RxD pin. The data recovery logic sam-
ples and low pass filters each incoming bit, thereby improving the noise immunity of the receiver.
The asynchronous reception operational range depends on the accuracy of the internal baud
rate clock, the rate of the incoming frames, and the frame size in number of bits.
The clock recovery logic synchronizes internal clock to the incoming serial frames.
illustrates the sampling process of the start bit of an incoming frame. The sample rate is 16 times
the baud rate for Normal mode, and 8 times the baud rate for Double Speed mode. The horizon-
tal arrows illustrate the synchronization variation due to the sampling process. Note the larger
time variation when using the double speed mode (U2X = 1) of operation. Samples denoted zero
are samples done when the RxD line is idle (that is, no communication activity).
Figure 73. Start Bit Sampling
When the clock recovery logic detects a high (idle) to low (start) transition on the RxD line, the
start bit detection sequence is initiated. Let sample 1 denote the first zero-sample as shown in
the figure. The clock recovery logic then uses samples 8, 9, and 10 for Normal mode, and sam-
ples 4, 5, and 6 for Double Speed mode (indicated with sample numbers inside boxes on the
Assembly Code Example
C Code Example
(U2X = 0)
(U2X = 1)
Sample
Sample
USART_Flush:
void USART_Flush( void )
{
}
RxD
sbis UCSRA, RXC
ret
in
rjmp USART_Flush
unsigned char dummy;
while ( UCSRA & (1<<RXC) ) dummy = UDR;
1. See “About Code Examples” on page 7.
r16, UDR
0
0
IDLE
(1)
0
1
1
2
(1)
3
2
4
5
3
6
7
4
8
START
9
5
10
11
6
12
13
7
14
ATmega16(L)
15
8
16
1
1
2
BIT 0
Figure 73
3
2
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