AT32UC3L0256 Atmel Corporation, AT32UC3L0256 Datasheet - Page 838

• 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

35.3.5
35.3.6
35.3.7
32145A–12/2011
WDT
GPIO
SPI
1. Clearing the Watchdog Timer (WDT) counter in second half of timeout period will
2. WDT Control Register does not have synchronization feedback
1. Clearing Interrupt flags can mask other interrupts
1. SPI data transfer hangs with CSR0.CSAAT==1 and MR.MODFDIS==0
2. Disabling SPI has no effect on the SR.TDRE bit
None.
issue a Watchdog reset
If the WDT counter is cleared in the second half of the timeout period, the WDT will immedi-
ately issue a Watchdog reset.
Fix/Workaround
Use twice as long timeout period as needed and clear the WDT counter within the first half
of the timeout period. If the WDT counter is cleared after the first half of the timeout period,
you will get a Watchdog reset immediately. If the WDT counter is not cleared at all, the time
before the reset will be twice as long as needed.
When writing to the Timeout Prescale Select (PSEL), Time Ban Prescale Select (TBAN),
Enable (EN), or WDT Mode (MODE) fieldss of the WDT Control Register (CTRL), a synchro-
nizer is started to propagate the values to the WDT clcok domain. This synchronization
takes a finite amount of time, but only the status of the synchronization of the EN bit is
reflected back to the user. Writing to the synchronized fields during synchronization can lead
to undefined behavior.
Fix/Workaround
-When writing to the affected fields, the user must ensure a wait corresponding to 2 clock
cycles of both the WDT peripheral bus clock and the selected WDT clock source.
-When doing writes that changes the EN bit, the EN bit can be read back until it reflects the
written value.
When clearing interrupt flags in a GPIO port, interrupts on other pins of that port, happening
in the same clock cycle will not be registered.
Fix/Workaround
Read the PVR register of the port before and after clearing the interrupt to see if any pin
change has happened while clearing the interrupt. If any change occurred in the PVR
between the reads, they must be treated as an interrupt.
When CSR0.CSAAT==1 and mode fault detection is enabled (MR.MODFDIS==0), the SPI
module will not start a data transfer.
Fix/Workaround
Disable mode fault detection by writing a one to MR.MODFDIS.
Disabling SPI has no effect on the SR.TDRE bit whereas the write data command is filtered
when SPI is disabled. Writing to TDR when SPI is disabled will not clear SR.TDRE. If SPI is
disabled during a PDCA transfer, the PDCA will continue to write data to TDR until its buffer
is empty, and this data will be lost.
Fix/Workaround
Disable the PDCA, add two NOPs, and disable the SPI. To continue the transfer, enable the
SPI and PDCA.
AT32UC3L0128/256
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