Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI Data Sheet

188

ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]

Atmel-8271H-AVR- ATmega-Datasheet_08/2014

Using any of the 5- to 8-bit character frame formats is possible, but impractical since the Receiver must change 
between using n and n+1 character frame formats. This makes full-duplex operation difficult since the 
Transmitter and Receiver uses the same character size setting. If 5- to 8-bit character frames are used, the 
Transmitter must be set to use two stop bit (USBSn = 1) since the first stop bit is used for indicating the frame 
type.

Do not use Read-Modify-Write instructions (SBI and CBI) to set or clear the MPCMn bit. The MPCMn bit shares 
the same I/O location as the TXCn Flag and this might accidentally be cleared when using SBI or CBI 
instructions.

For standard crystal and resonator frequencies, the most commonly used baud rates for asynchronous 
operation can be generated by using the UBRRn settings in 

. UBRRn 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 resistance when the error ratings are high, especially for large 
serial frames (see 

). The error values are calculated using the 

following equation:

Note:

1. UBRRn = 0, Error = 0.0%

Error[%]

BaudRate

Closest Match

BaudRate

--------------------------------------------------

1

–







 100%



=

2400

25

0.2%

51

0.2%

47

0.0%

95

0.0%

51

0.2%

103

0.2%

4800

12

0.2%

25

0.2%

23

0.0%

47

0.0%

25

0.2%

51

0.2%

9600

6

-7.0%

12

0.2%

11

0.0%

23

0.0%

12

0.2%

25

0.2%

14.4k

3

8.5%

8

-3.5%

7

0.0%

15

0.0%

8

-3.5%

16

2.1%

19.2k

2

8.5%

6

-7.0%

5

0.0%

11

0.0%

6

-7.0%

12

0.2%

28.8k

1

8.5%

3

8.5%

3

0.0%

7

0.0%

3

8.5%

8

-3.5%

38.4k

1

-18.6%

2

8.5%

2

0.0%

5

0.0%

2

8.5%

6

-7.0%

57.6k

0

8.5%

1

8.5%

1

0.0%

3

0.0%

1

8.5%

3

8.5%

76.8k

–

–

1

-18.6%

1

-25.0%

2

0.0%

1

-18.6%

2

8.5%

115.2k

–

–

0

8.5%

0

0.0%

1

0.0%

0

8.5%

1

8.5%

230.4k

–

–

–

–

–

–

0

0.0%

–

–

–

–

250k

–

–

–

–

–

–

–

–

–

–

0

0.0%

Max.

62.5kbps

125kbps

115.2kbps

230.4kbps

125kbps

250kbps