AT90USB646 datasheet(448/459 Pages) ATMEL

448 / 459 page

448

7593H–AVR–11/08

ATmega32U6/AT90USB64/128

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.

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 mode again it may wake up several times.

Problem Fix/workaround

A sof t w a r e w o r k a r ou nd is t o wa it w i th p e r f or m i ng t he sle e p inst r u ctio n un til

TCNT2>OCR2+1.

39. ATmega32U6 Errata.

• Spike on TWI pins when TWI is enabled

• Async timer interrupt wake up from sleep generate multiple interrupts

2. Spike on TWI pins when TWI is enabled

100 ns negative spike occurs on SDA and SCL pins when TWI is enabled.

Problem Fix/workaround

No known workaround, enable ATmega32U6/AT90USB64/128 TWI first versus the others

nodes of the TWI network.

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 mode again it may wake up several times.

Problem Fix/workaround

A sof t w a r e w o r k a r ou nd is t o wa it w i th p e r f or m i ng t he sle e p inst r u ctio n un til

TCNT2>OCR2+1.

AT90USB646 Datasheet(PDF) 448 Page - ATMEL Corporation