Data Book Updates and Changes
30
12-35 Table 7: remove t his note: “Not e: When changing th e ISC11/ISC10 bits , INT1 must be disable d by clea ring it s Inter -
rupt Enable bi t in the GIMSK registe r. Otherwise an int errupt can occur when the bits are changed.”
Table 8: r emove this no te: “Not e: When ch anging the ISC01/ ISC00 bit s, I NT0 must be dis abl ed by clear ing its Int er-
rupt Enable bi t in the GIMSK registe r. Otherwise an int errupt can occur when the bits are changed.”
At the end of the Interrupt Sense Control 2 description add this text: “When changing the ISC2 bit, an interrupt
can occur. Therefore, it is recommended to first disable INT2 by clearing its Interrupt Enable bit in the GIMSK reg-
ister. Then, the ISC2 bit can be changed. Finally, the INT2 interrupt flag should be cleared by writing a logical one
to its Interrupt Flag bit in the GIFR register before the int e rrupt is re-enabled. ”
12-36 At the end of the Power Save Mode section, add the paragraph “If the asynchronous timer is NOT clocked asyn-
chronously, Power Down Mode is recommended instead of Power Save Mode because the contents of the regis-
ters in the asynchronous timer should be considered undefined after wake up in Power Save Mode even if AS2 is
0.”
12-46 Replace last paragraph on page,
“When asynchronous operation is selected, the 32 kHz oscillator for Timer/Counter2 is always running, except in power down
mode. After a power up reset or wake-up from power down, the user should be aware of the fact that this oscillator might take
as long as one second to stabilize. Therefore, the content of all Timer/Counter2 registers must be considered lost after a wake-
up from power down, due to the unstable clock signal. The user is advised to wait for at least one second before using
Timer/Counter2 after power-up or wake-up from power down.”
by
“When the asynchronous operation is selected, the 32 kHZ oscillator for Timer/Counter2 is always running, except in power
down mode. After a power up reset or wake-up from power down, the user should be aware of the fact that this oscillator
might take as long as one second to stabilize. The user is advised to wait for at least one second before using Timer/Counter2
after power-up or wake-up from power down. The contents of all Timer/Counter2 registers must be considered lost after a
wake-up from power down due to unstable clock signal upon start-up, regardless of whether the oscillator is in use or a clock
signal is applied to the TOSC pin.”
12-55 In the note for Table 20, add “To avoid unintentional MCU resets, the Watchdog Timer should be disabled or reset
before changing the Watchdog Timer Prescale Select.”
12-56 In the EEPROM Read/Write Access description, replace the second sentence “The write access time is in the
range of 2.5 - 4 ms, depending on the Vcc voltages” by “The write access time is in the range of 1.9 - 3.4 ms,
depending of the frequency of the RC oscillator used to time the EEPROM access time. See table 21 for details.”
In t he last sentence of the EEPROM Read/Wr it e Access description, replace “When the EEPROM is read or wri t-
ten, the CPU is hal ted for tw o clock cycles before the next instruction is executed. ” by “When the EEPROM is writ-
ten, the CPU is halted for two clock cycles before the next instruction is executed. When the EEPROM is read, the
CPU is halted for four clock cycles before the next instruction is execut ed.”
In the EEPROM Control Register descr ipt ion, cha nge the i nitial value of EEW E from “0” to “X”.
12-57 In the desc ript ion of bi t 1 - EEWE: EEPROM write Enabl e, repl ace “When the writ e access time (typical ly 2.5 ms at
Vcc = 5V or 4 ms at Vcc = 2.7V) has elapsed, “ by “W hen the write access time has elapsed, “
In the Bit1 - EEWE: EEPROM Write Enable description, change “4. Write a logical one to the EEMWE bit in
EECR” to “4. W rit e a logica l one to the EEMWE bit in EECR (to be abl e to writ e a logical one to the EEMWE bit, the
EEWE bit must be written to zero in the same cycle).”
Under “Prevent EEPROM corruption”, note 3 replace the text: “Flash memory can not be updated by the CPU,
and will not be subject to corruption.” by “Flash memory can not be updated by the CPU unless the boot loader
soft ware sup ports wri ting to the FLASH and the Boot Lock bits ar e conf igured so th at writ ing to the FLASH memory
from CPU is allowed. See Boot Loader Support on page 12-98 for details.”