ATmega8 Atmel Corporation, ATmega8 Datasheet - Page 144

• 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

Asynchronous
Operational Range
144
ATmega8(L)
The operational range of the Receiver is dependent on the mismatch between the received bit
rate and the internally generated baud rate. If the Transmitter is sending frames at too fast or too
slow bit rates, or the internally generated baud rate of the Receiver does not have a similar (see
Table
The following equations can be used to calculate the ratio of the incoming data rate and internal
Receiver baud rate.
D
S
S
S
R
Table 53
that Normal Speed mode has higher toleration of baud rate variations.
Table 53. Recommended Maximum Receiver Baud Rate Error for Normal Speed Mode
(U2X = 0)
Table 54. Recommended Maximum Receiver Baud Rate Error for Double Speed Mode
(Data + Parity Bit)
F
M
slow
(Data + Parity Bit)
Sum of character size and parity size (D = 5-bit to 10-bit)
Samples per bit. S = 16 for Normal Speed mode and S = 8 for Double Speed mode
First sample number used for majority voting. S
Double Speed mode
Middle sample number used for majority voting. S
Double Speed mode
is the ratio of the slowest incoming data rate that can be accepted in relation to the
Receiver baud rate. R
accepted in relation to the Receiver baud rate
53) base frequency, the Receiver will not be able to synchronize the frames to the start bit.
D#
10
D#
R
10
5
6
7
8
9
and
5
6
7
8
9
(U2X = 1)
slow
Table 54
=
------------------------------------------ -
S 1
–
(
94.12
94.92
95.52
96.00
96.39
96.70
R
D
+
93.20
94.12
94.81
95.36
95.81
96.17
(%)
R
list the maximum Receiver baud rate error that can be tolerated. Note
slow
(%)
+
D S ⋅
slow
1
fast
)S
+
is the ratio of the fastest incoming data rate that can be
S
105.66
104.92
104.35
103.90
103.53
103.23
F
106.67
105.79
105.11
104.58
104.14
103.78
R
(%)
R
(%)
fast
fast
+5.66/-5.88
+4.92/-5.08
+4.35/-4.48
+3.90/-4.00
+3.53/-3.61
+3.23/-3.30
Max Total
+5.79/-5.88
+5.11/-5.19
+4.58/-4.54
+4.14/-4.19
+3.78/-3.83
Error (%)
+6.67/-6.8
Max Total
Error (%)
F
R
= 8 for Normal Speed and S
M
fast
= 9 for Normal Speed and S
=
-----------------------------------
(
Recommended Max
Recommended Max
D
Receiver Error (%)
Receiver Error (%)
(
+
D
1
+
)S
2
±2.5
±2.0
±1.5
±1.5
±1.5
±1.0
±3.0
±2.0
±2.0
±2.0
±1.5
±1.5
)S
+
S
M
2486Z–AVR–02/11
F
= 4 for
M
= 5 for