380
2552K–AVR–04/11
ATmega329/3290/649/6490
34.2
ATmega3290
34.2.1
ATmega3290 rev. C
Interrupts may be lost when writing the timer registers in the asynchronous timer
1.
Interrupts may be lost when writing the timer registers in the asynchronous timer
The interrupt will be lost if a timer register that is synchronous timer clock is written when the
asynchronous Timer/Counter register (TCNTx) is 0x00.
Problem Fix/Wortkaround
Always check that the asynchronous Timer/Counter register neither have the value 0xFF nor
0x00 before writing to the asynchronous Timer Control Register (TCCRx), asynchronous
Timer Counter Register (TCNTx), or asynchronous Output Compare Register (OCRx).
34.2.2
ATmega3290 rev. B
Not sampled.
34.2.3
ATmega3290 rev. A
LCD contrast voltage too high
Interrupts may be lost when writing the timer registers in the asynchronous timer
1.
LCD contrast voltage too high
When the LCD is active and using low power waveform, the LCD contrast voltage can be too
high. This occurs when V
CC is higher than VLCD, and when using low LCD drivetime.
Problem Fix/Workaround
There are several possible workarounds:
- Use normal waveform instead of low power waveform
- Use drivetime of 375 s or longer
2.
Interrupts may be lost when writing the timer registers in the asynchronous timer
The interrupt will be lost if a timer register that is synchronous timer clock is written when the
asynchronous Timer/Counter register (TCNTx) is 0x00.
Problem Fix/Wortkaround
Always check that the asynchronous Timer/Counter register neither have the value 0xFF nor
0x00 before writing to the asynchronous Timer Control Register (TCCRx), asynchronous
Timer Counter Register (TCNTx), or asynchronous Output Compare Register (OCRx).