ATmega32A Atmel Corporation, ATmega32A Datasheet - Page 172

• Manufacturer Part Number: ATmega32A
• Manufacturer: Atmel Corporation

Specifications of ATmega32A

• Flash (kbytes): 32 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: 32
• Ext Interrupts: 3
• 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): 2
• Eeprom (bytes): 1024
• 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: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

19.12 Examples of Baud Rate Setting
Table 19-9.
8155C–AVR–02/11
Baud
Rate
(bps)
2400
4800
9600
14.4k
19.2k
28.8k
38.4k
57.6k
76.8k
115.2k
UBRR
25
12
6
3
2
1
1
0
–
–
Examples of UBRR Settings for Commonly Used Oscillator Frequencies
U2X = 0
f
-18.6%
osc
-7.0%
Error
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
= 1.0000MHz
• Bit 15 – URSEL: Register Select
This bit selects between accessing the UBRRH or the UCSRC Register. It is read as zero when
reading UBRRH. The URSEL must be zero when writing the UBRRH.
• Bit 14:12 – Reserved Bits
These bits are reserved for future use. For compatibility with future devices, these bit must be
written to zero when UBRRH is written.
• 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 8 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 UBRRL 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 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
U2X = 1
-18.6%
-3.5%
-7.0%
Error
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
163). The error values are calculated using the following equation:
UBRR
47
23
11
7
5
3
2
1
0
1
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
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%
–
UBRR
⎞
⎠
51
25
12
•
8
6
3
2
1
1
0
100%
U2X = 0
“Asynchronous Operational
f
-18.6%
-3.5%
-7.0%
osc
Table
Error
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
ATmega32A
= 2.0000MHz
19-9. UBRR values
UBRR
103
51
25
16
12
8
6
3
2
1
U2X = 1
-3.5%
-7.0%
Error
0.2%
0.2%
0.2%
2.1%
0.2%
8.5%
8.5%
8.5%
172