AT32UC3B1256-AUR Atmel, AT32UC3B1256-AUR Datasheet - Page 670

• Manufacturer Part Number: AT32UC3B1256-AUR
• Description: MCU AVR32 256K FLASH 48-TQFP
• Manufacturer: Atmel
• Series: AVR®32 UC3r

Specifications of AT32UC3B1256-AUR

• Package / Case: 48-TQFP, 48-VQFP
• Voltage - Supply (vcc/vdd): 1.65 V ~ 1.95 V
• Operating Temperature: -40°C ~ 85°C
• Speed: 60MHz
• Number Of I /o: 28
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 32K x 8
• Program Memory Size: 256KB (256K x 8)
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, DMA, POR, PWM, WDT
• Connectivity: I²C, IrDA, SPI, SSC, UART/USART, USB
• Core Size: 32-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

32059J–12/2010
10. RETE instruction does not clear SREG[L] from interrupts
11. Exceptions when system stack is protected by MPU
The RETE instruction clears SREG[L] as expected from exceptions.
Fix/Workaround
When using the STCOND instruction, clear SREG[L] in the stacked value of SR before
returning from interrupts with RETE.
RETS behaves incorrectly when MPU is enabled and MPU is configured so thatsystem
stack is not readable in unprivileged mode.
Fix/Workaround
Workaround 1: Make system stack readable in unprivileged mode,
or
Workaround 2: Return from supervisor mode using rete instead of rets. This requires: 1.
Changing the mode bits from 001b to 110b before issuing the instruction.
Updating the mode bits to the desired value must be done using a single mtsr instruction so
it is done atomically. Even if this step is described in general as not safe in the UC technical
reference guide, it is safe in this very specific case.
2. Execute the RETE instruction.
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