ATmega8 Atmel Corporation, ATmega8 Datasheet - Page 153

• Manufacturer Part Number: ATmega8
• Manufacturer: Atmel Corporation

Specifications of ATmega8

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 2
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 1
• Pwm Channels: 3
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

Examples of Baud
Rate Setting
Table 60. Examples of UBRR Settings for Commonly Used Oscillator Frequencies
1.
2486Z–AVR–02/11
Baud
Rate
(bps)
2400
4800
9600
14.4k
19.2k
28.8k
38.4k
57.6k
76.8k
115.2k
230.4k
250k
Max
(1)
UBRR = 0, Error = 0.0%
UBRR
25
12
6
3
2
1
1
0
–
–
–
–
62.5kbps
U2X = 0
f
-18.6%
osc
-7.0%
Error
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
–
–
= 1.0000MHz
For standard crystal and resonator frequencies, the most commonly used baud rates for asyn-
chronous operation can be generated by using the UBRR settings in
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
Range” on page
UBRR
51
25
12
8
6
3
2
1
1
0
–
–
125kbps
U2X = 1
-18.6%
-3.5%
-7.0%
Error
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
144). The error values are calculated using the following equation:
UBRR
47
23
11
7
5
3
2
1
0
–
–
1
115.2kbps
U2X = 0
Error[%]
f
-25.0%
osc
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
–
= 1.8432MHz
=
⎛
⎝
BaudRate
------------------------------------------------------- - 1
UBRR
95
47
23
15
11
BaudRate
7
5
3
2
1
0
–
230.4kbps
U2X = 1
Closest Match
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
–
UBRR
⎞
⎠
51
25
12
•
8
6
3
2
1
1
0
–
–
100%
125kbps
U2X = 0
“Asynchronous Operational
f
-18.6%
-3.5%
-7.0%
osc
Error
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
Table
–
-
ATmega8(L)
= 2.0000MHz
60. UBRR values
UBRR
103
51
25
16
12
8
6
3
2
1
–
0
250kbps
U2X = 1
-3.5%
-7.0%
Error
0.2%
0.2%
0.2%
2.1%
0.2%
8.5%
8.5%
8.5%
0.0%
–
153