AT32UC3L0256 Atmel Corporation, AT32UC3L0256 Datasheet - Page 380

• Manufacturer Part Number: AT32UC3L0256
• Manufacturer: Atmel Corporation

Specifications of AT32UC3L0256

• Flash (kbytes): 256 Kbytes
• Pin Count: 48
• Max. Operating Frequency: 50 MHz
• Cpu: 32-bit AVR
• # Of Touch Channels: 17
• Hardware Qtouch Acquisition: Yes
• Max I/o Pins: 36
• Ext Interrupts: 36
• Usb Speed: No
• Usb Interface: No
• Spi: 5
• Twi (i2c): 2
• Uart: 4
• Lin: 4
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 12
• Adc Speed (ksps): 460
• Analog Comparators: 8
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 16
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.62 to 3.6
• Operating Voltage (vcc): 1.62 to 3.6
• Fpu: No
• Mpu / Mmu: Yes / No
• Timers: 6
• Output Compare Channels: 18
• Input Capture Channels: 12
• Pwm Channels: 35
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

Table 19-3.
19.6.1.3
32145A–12/2011
Source Clock (Hz)
12 000 000
12 288 000
14 318 180
14 745 600
18 432 000
24 000 000
24 576 000
25 000 000
32 000 000
32 768 000
33 000 000
40 000 000
50 000 000
60 000 000
3 686 400
4 915 200
5 000 000
7 372 800
8 000 000
Fractional Baud Rate in Asynchronous Mode
Baud Rate Example (OVER=0)
Expected Baud
The baud rate is calculated with the following formula (OVER=0):
The baud rate error is calculated with the following formula. It is not recommended to work with
an error higher than 5%.
The baud rate generator has a limitation: the source frequency is always a multiple of the baud
rate. An approach to this problem is to integrate a high resolution fractional N clock generator,
outputting fractional multiples of the reference source clock. This fractional part is selected with
the Fractional Part field (BRGR.FP), and is activated by giving it a non-zero value. The resolu-
tion is one eighth of CD. The resulting baud rate is calculated using the following formula:
The modified architecture is presented below:
Rate (bit/s)
BaudRate
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
38 400
BaudRate
=
------------------------------------------------------------------- -
⎛
⎝
Error
8 2 OVER
Calculation Result
–
SelectedClock
=
=
1
12.00
13.02
19.53
20.00
23.30
24.00
30.00
39.06
40.00
40.69
52.08
53.33
53.71
65.10
81.38
97.66
6.00
8.00
8.14
CLKUSART
–
⎛
⎝
ExpectedBaudRate
-------------------------------------------------- -
⎛
⎝
CD
ActualBaudRate
+
FP
------ -
8
⎞
⎠
⎞
⎠
CD
CD
12
13
20
20
23
24
30
39
40
40
52
53
54
65
81
98
6
8
8
⎞
⎠
16
Actual Baud Rate (bit/s)
AT32UC3L0128/256
38 400.00
38 400.00
39 062.50
38 400.00
38 461.54
37 500.00
38 400.00
38 908.10
38 400.00
38 400.00
38 461.54
38 400.00
38 109.76
38 461.54
38 641.51
38 194.44
38 461.54
38 580.25
38 265.31
0.00%
0.00%
1.70%
0.00%
0.16%
2.40%
0.00%
1.31%
0.00%
0.00%
0.16%
0.00%
0.76%
0.16%
0.63%
0.54%
0.16%
0.47%
0.35%
Error
380