AT32UC3L0256 Atmel Corporation, AT32UC3L0256 Datasheet - Page 779

• 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

31.6.6.5
31.6.6.6
31.6.6.7
31.6.6.8
32145A–12/2011
Resetting the AW
2-pin Mode
Baud Rate Clock
Service Access Bus
The aWire master can reset the AW slave by pulling the RESET_N pin low for 20 ms. This is
equivalent to disabling and then enabling AW.
To avoid using special hardware when using a normal UART device as aWire master, the aWire
slave has a 2-pin mode where one pin is used as input and on pin is used as output. To enable
this mode the 2_PIN_MODE command must be sent. After sending the command, all responses
will be sent on the DATAOUT pin instead of the RESET_N pin. Commands are still received on
the RESET_N pin.
The communication speed is set by the master in the sync field of the command. The AW will
use this to resynchronize its baud rate clock and reply on this frequency. The minimum fre-
quency of the communication is 1 kHz. The maximum frequency depends on the internal clock
source for the AW (RC120M). The baud rate clock is generated by AW with the following
formula:
Where
the value returned by the BAUD_RATE response.
To find the max frequency the user can issue the TUNE command to the AW to make it return
the TUNE value. This value can be used to compute the
quency (
The AVR32 architecture offers a common interface for access to On-Chip Debug, programming,
and test functions. These are mapped on a common bus called the Service Access Bus (SAB),
which is linked to the aWire through a bus master module, which also handles synchronization
between the aWire and SAB clocks.
For more information about the SAB and a list of SAB slaves see the Service Access Bus
chapter.
SAB Clock
When accessing the SAB through the aWire there are no limitations on baud rate frequency
compared to chip frequency, although there must be an active system clock in order for the SAB
accesses to complete. If the system clock (CLK_SYS) is switched off in sleep mode, activity on
the aWire pin will restart the CLK_SYS automatically, without waking the device from sleep.
aWire masters may optimize the transfer rate by adjusting the baud rate frequency in relation to
the CLK_SYS. This ratio can be measured with the MEMORY_SPEED_REQUEST command.
When issuing the MEMORY_SPEED_REQUEST command a counter value CV is returned. CV
can be used to calculate the SAB speed (
f
br
f
brmax
is the baud rate frequency and
) is then:
f
aw
f
f
brmax
f
sab
aw
=
) using this formula:
TUNE
---------------------------- -
is the frequency of the internal RC120M. TUNE is
=
8
f
-------
aw
4
f
br
AT32UC3L0128/256
f
aw
. The maximum operational fre-
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