ATMEGA161_14 Datasheet, PDF (1/3 Pages) ATMEL Corporation – Brown-out Detector may cause the Device to be Stuck in Reset State

Errata
• Brown-out Detector may cause the Device to be Stuck in Reset State
• PWM not Phase Correct
• Increased Interrupt Latency
• Interrupt Return Fails when Stack Pointer Addresses the External Memory
• Writing UBBRH Affects both UART0 and UART1
• Store Program Memory Instruction May Fail
6. Brown-out Detecor may cause the Device to be Stuck in Reset State
When the internal Brown-out Detector is enabled, the device may hang in Reset
state regardless of the V_CC level.
Problem Fix/Workaround
Use external Brown-out Detector and do not enable internal Brown-out Detector
(leave BODEN Fuse unprogrammed).
5. PWM not Phase Correct
In phase correct PWM mode, a change from OCRx = TOP to anything less than
TOP does not change the OCx output. This gives a phase error in the following
period.
Problem Fix/Workaround
Make sure this issue is not harmful to the application.
4. Increased Interrupt Latency
In this device, some instructions are not interruptable, and will cause the interrupt
latency to increase. The only practical problem concerns a loop followed by a two-
word instruction while waiting for an interrupt. The loop may consist of a branch
instruction or an absolute or relative jump back to itself like this:
loop: rjmp loop
<Two-word instruction>
In this case, a dead-lock situation arises.
Problem Fix/Workaround
In assembly, insert a nop instruction immediately after a loop to itself. The prob-
lem will normally be detected during development. In C, the only construct that will
give this problem is an empty “for” loop; “for(;;)”. Use “while(1)” or “do{} while (1)”
to avoid the problem.
3. Interrupt Return Fails when Stack Pointer Addresses the External Memory
When Stack Pointer addresses external memory (SPH:SPL > $45F), returning
from interrupt will fail. The program counter will be updated with a wrong value
and thus the program flow will be corrupted.
Problem Fix/Workaround
Address the stack pointer to internal SRAM or disable interrupts while Stack
Pointer addresses external memory.
8-bit
Microcontroller
with 16K Bytes
Flash
ATmega161(L)
Rev. E
Errata Sheet
Rev. 2473B–AVR–05/02
1