ATmega8515 Atmel Corporation, ATmega8515 Datasheet - Page 151

• Manufacturer Part Number: ATmega8515
• Manufacturer: Atmel Corporation

Specifications of ATmega8515

• Flash (kbytes): 8 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 35
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.5
• 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: 2
• Output Compare Channels: 3
• Input Capture Channels: 1
• Pwm Channels: 3
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

Multi-processor
Communication Mode
2512K–AVR–01/10
Table 61. Recommended Maximum Receiver Baud Rate Error for Normal Speed Mode
(U2X = 0)
Table 62. Recommended Maximum Receiver Baud Rate Error for Double Speed Mode
(U2X = 1)
The recommendations of the maximum Receiver Baud Rate error was made under the
assumption that the Receiver and Transmitter equally divides the maximum total error.
There are two possible sources for the Receiver’s baud rate error. The Receiver’s sys-
tem clock (XTAL) will always have some minor instability over the supply voltage range
and the temperature range. When using a crystal to generate the system clock, this is
rarely a problem, but for a resonator the system clock may differ more than 2% depend-
ing of the resonators tolerance. The second source for the error is more controllable.
The baud rate generator can not always do an exact division of the system frequency to
get the baud rate wanted. In this case an UBRR value that gives an acceptable low error
can be used if possible.
Setting the Multi-processor Communication mode (MPCM) bit in UCSRA enables a fil-
tering function of incoming frames received by the USART Receiver. Frames that do not
contain address information will be ignored and not put into the receive buffer. This
effectively reduces the number of incoming frames that has to be handled by the CPU,
in a system with multiple MCUs that communicate via the same serial bus. The Trans-
mitter is unaffected by the MPCM setting, but has to be used differently when it is a part
of a system utilizing the Multi-processor Communication mode.
If the Receiver is set up to receive frames that contain 5 to 8 data bits, then the first stop
bit indicates if the frame contains data or address information. If the Receiver is set up
for frames with nine data bits, then the ninth bit (RXB8) is used for identifying address
and data frames. When the frame type bit (the first stop or the ninth bit) is one, the frame
contains an address. When the frame type bit is zero the frame is a data frame.
# (Data+Parity Bit)
# (Data+Parity Bit)
10
10
D
5
6
7
8
9
D
5
6
7
8
9
R
R
slow
93.20
94.12
94.81
95.36
95.81
96.17
slow
94.12
94.92
95.52
96.00
96.39
96.70
(%)
(%)
R
R
106.67
105.79
105.11
104.58
104.14
103.78
105.66
104.92
104.35
103.90
103.53
103.23
fast
fast
(%)
(%)
+5.79/-5.88
+5.11/-5.19
+4.58/-4.54
+4.14/-4.19
+3.78/-3.83
+5.66/-5.88
+4.92/-5.08
+4.32/-4.48
+3.90/-4.00
+3.53/-3.61
+3.23/-3.30
Max Total
+6.67/-6.8
Max Total
Error (%)
Error (%)
ATmega8515(L)
Recommended Max
Recommended Max
Receiver Error (%)
Receiver Error (%)
± 3.0
± 2.5
± 2.0
± 2.0
± 1.5
± 1.5
± 2.5
± 2.0
± 1.5
± 1.5
± 1.5
± 1.0
151