ATmega88 Automotive Atmel Corporation, ATmega88 Automotive Datasheet - Page 188

• Manufacturer Part Number: ATmega88 Automotive
• Manufacturer: Atmel Corporation

Specifications of ATmega88 Automotive

• 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: 24
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• 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 150
• 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: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

17.9.5
17.10 Examples of Baud Rate Setting
Table 17-9.
188
Baud
Rate
(bps)
2400
4800
9600
14.4k
19.2k
28.8k
38.4k
ATmega48/88/168 Automotive
USART Baud Rate Registers – UBRRnL and UBRRnH
UBRR
n
25
12
6
3
2
1
1
U2Xn = 0
Examples of UBRRn Settings for Commonly Used Oscillator Frequencies
f
Error
-18.6%
osc
-7.0%
0.2%
0.2%
8.5%
8.5%
8.5%
= 1.0000 MHz
• Bit 15:12 – Reserved Bits
These bits are reserved for future use. For compatibility with future devices, these bit must be
written to zero when UBRRnH is written.
• Bit 11:0 – UBRR11:0: USART Baud Rate Register
This is a 12-bit register which contains the USART baud rate. The UBRRnH contains the four
most significant bits, and the UBRRnL contains the eight least significant bits of the USART
baud rate. Ongoing transmissions by the Transmitter and Receiver will be corrupted if the baud
rate is changed. Writing UBRRnL will trigger an immediate update of the baud rate prescaler.
For standard crystal and resonator frequencies, the most commonly used baud rates for asyn-
chronous operation can be generated by using the UBRRn settings in
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 resis-
tance when the error ratings are high, especially for large serial frames (see
Operational Range” on page
Bit
Read/Write
Initial Value
UBRR
n
51
25
12
8
6
3
2
U2Xn = 1
Error
-3.5%
-7.0%
0.2%
0.2%
0.2%
8.5%
8.5%
R/W
15
R
–
7
0
0
UBRR
n
47
23
11
7
5
3
2
R/W
U2Xn = 0
14
R
–
6
0
0
Error[%]
181). The error values are calculated using the following equation:
f
Error
osc
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
R/W
= 1.8432 MHz
13
=
R
–
5
0
0
BaudRate
------------------------------------------------------- - 1
UBRR
n
95
47
23
15
11
R/W
BaudRate
7
5
12
R
–
4
0
0
U2Xn = 1
UBRRn[7:0]
Closest Match
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
R/W
R/W
11
3
0
0
–
UBRR
n
R/W
R/W
51
25
12
10
UBRRn[11:8]
2
0
0
8
6
3
2
U2Xn = 0
100%
f
Error
osc
-3.5%
-7.0%
0.2%
0.2%
0.2%
8.5%
8.5%
R/W
R/W
9
1
0
0
= 2.0000 MHz
Table
UBRR
n
R/W
R/W
“Asynchronous
103
8
0
0
0
51
25
16
12
8
6
17-9. UBRRn
U2Xn = 1
7530I–AVR–02/10
UBRRnH
UBRRnL
Error
-3.5%
-7.0%
0.2%
0.2%
0.2%
2.1%
0.2%