466130 Datasheet, PDF (30/36 Pages) ATMEL Corporation – 8-bit Microcontroller with 64/128K Bytes of ISP Flash

Problem Fix/workaround
No known workaround, enable ATmega32U6/AT90USB64/128 TWI first versus the others
nodes of the TWI network.
2. High current consumption in sleep mode
If a pending interrupt cannot wake the part up from the selected mode, the current consump-
tion will increase during sleep when executing the SLEEP instruction directly after a SEI
instruction.
Problem Fix/workaround
Before entering sleep, interrupts not used to wake up the part from the sleep mode should
be disabled.
1. Asynchronous timer interrupt wake up from sleep generates multiple interrupts
If the CPU core is in sleep and wakes-up from an asynchronous timer interrupt and then go
back in sleep again it may wake up multiple times.
Problem Fix/workaround
A software workaround is to wait with performing the sleep instruction until
TCNT2>OCR2+1.
30 ATmega32U6/AT90USB64/128
7593JS–AVR–03/09