ATMEGA323-8AC Atmel, ATMEGA323-8AC Datasheet - Page 99

• Manufacturer Part Number: ATMEGA323-8AC
• Description: IC AVR MCU 32K 8MHZ COM 44TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA323-8AC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K 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: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: ATMEGA3238AC

Examples of Baud Rate
Setting
1457G–AVR–09/03
• Bit 11:0 – UBRR11:0: USART Baud Rate Register
This is a 12-bit register which contains the USART baud rate. The UBRRH contains the
four most significant bits, and the UBRRL contains the eight least significant bits of the
USART baud rate. Ongoing transmissions by the Transmitter and Receiver will be cor-
rupted if the baud rate is changed. Writing UBRRL will trigger an immediate update of
the baud rate prescaler.
For standard crystal and resonator frequencies, the most commonly used baud rates for
asynchronous operation can be generated by using the UBRR settings in Table 36.
UBRR values which yield an actual baud rate differing less than 0.5% from the target
baud rate, are bold in the table. Higher error ratings are acceptable, but the Receiver will
have less noise resistance when the error ratings are high, especially for large serial
frames (see “Asynchronous Operational Range” on page 89). The error values are cal-
culated using the following equation:
Table 36. Examples of UBRR Settings for Commonly Used Oscillator Frequencies –
UBRR = 0, Error = 0.0%
Baud
Rate
(bps)
2400
4800
9600
14.4K
19.2K
28.8K
38.4K
57.6K
76.8K
115.2K
230.4K
250K
Max
Baud
Rate
(bps)
2400
4800
9600
UBRR
UBRR
25
12
51
25
12
6
3
2
1
1
0
–
–
–
–
62.5 Kbps
U2X = 0
U2X = 0
f
-18.6%
osc
-7.0%
Error
f
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
0.2%
0.2%
0.2%
Error
osc
–
–
–
–
Error[%]
= 1.0000 MHz
= 2.0000 MHz
UBRR
UBRR
103
=
51
25
12
51
25
8
6
3
2
1
1
0
–
–

125 Kbps
U2X = 1
U2X = 1
BaudRate
------------------------------------------------------- - 1
-18.6%
BaudRate
-3.5%
-7.0%
Error
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
0.2%
0.2%
0.2%
Error
–
–
Closest Match
UBRR
UBRR
47
23
11
95
47
23
7
5
3
2
1
1
0
–
–
115.2 Kbps
U2X = 0
U2X = 0
–


ATmega323(L)
f
-25.0%
osc
Error
f
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
100%
Error
osc
–
–
= 1.8432 MHz
= 3.6864 MHz
UBRR
UBRR
191
95
47
23
15
11
95
47
7
5
3
2
1
0
–
230.4 Kbps
U2X = 1
U2X = 1
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Error
0.0%
0.0%
0.0%
–
99