at32uc3b0512-z2ues ATMEL Corporation, at32uc3b0512-z2ues Datasheet - Page 653

• Manufacturer Part Number: at32uc3b0512-z2ues
• Description: 32-bit Avr Microcontroller
• Manufacturer: ATMEL Corporation

31.1.2.8
31.1.2.9
32059J–12/2010
Processor and Architecture
TWI
2. Transfer error will stall a transmit peripheral handshake interface
1. The TWI RXRDY flag in SR register is not reset when a software reset is performed
2. TWI in master mode will continue to read data
3. TWI slave behaves improperly if master acknowledges the last transmitted data byte
1. LDM instruction with PC in the register list and without ++ increments Rp
2. RETE instruction does not clear SREG[L] from interrupts
3. Privilege violation when using interrupts in application mode with protected system
Wrong PDCA behavior when using two PDCA channels with the same PID.
Fix/Workaround
The same PID should not be assigned to more than one channel.
If a tranfer error is encountered on a channel transmitting to a peripheral, the peripheral
handshake of the active channel will stall and the PDCA will not do any more transfers on
the affected peripheral handshake interface.
Fix/workaround:
Disable and then enable the peripheral after the transfer error.
The TWI RXRDY flag in SR register is not reset when a software reset is performed.
Fix/Workaround
After a Software Reset, the register TWI RHR must be read.
TWI in master mode will continue to read data on the line even if the shift register and the
RHR register are full. This will generate an overrun error.
Fix/workaround
To prevent this, read the RHR register as soon as a new RX data is ready.
before a STOP condition
In I2C slave transmitter mode, if the master acknowledges the last data byte before a STOP
condition (what the master is not supposed to do), the following TWI slave receiver mode
frame may contain an inappropriate clock stretch. This clock stretch can only be stopped by
resetting the TWI.
Fix/Workaround
If the TWI is used as a slave transmitter with a master that acknowledges the last data byte
before a STOP condition, it is necessary to reset the TWI beforeentering slave receiver
mode.
For LDM with PC in the register list: the instruction behaves as if the ++ field is always set, ie
the pointer is always updated. This happens even if the ++ field is cleared. Specifically, the
increment of the pointer is done in parallel with the testing of R12.
Fix/Workaround
None.
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.
stack
If the system stack is protected by the MPU and an interrupt occurs in application mode, an
MPU DTLB exception will occur.
AT32UC3B
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