Datasheet

166
ATtiny13
2535E–AVR–10/04
Errata The revision letter in this section refers to the revision of the ATtiny13 device.
ATtiny13 Rev. D • EEPROM can not be written below 1.9 Volt
1. EEPROM can not be written below 1.9 Volt
Writing the EEPROM at V
CC
below 1.9 volts might fail.
Problem Fix/Workaround
Do not write the EEPROM when V
CC
is below 1.9 volts.
ATtiny13 Rev. B • Wrong values read after Erase Only operation
• High Voltage Serial Programming Flash, EEPROM, Fuse and Lock Bits may fail
• Device may lock for further programming
• debugWIRE communication not blocked by lock-bits
• Watchdog Timer Interrupt disabled
• EEPROM can not be written below 1.9 Volt
1. Wrong values read after Erase Only operation
At supply voltages below 2.7 V, an EEPROM location that is erased by the Erase
Only operation may read as programmed (0x00).
Problem Fix/Workaround
If it is necessary to read an EEPROM location after Erase Only, use an Atomic Write
operation with 0xFF as data in order to erase a location. In any case, the Write Only
operation can be used as intended. Thus no special considerations are needed as
long as the erased location is not read before it is programmed.
2. High Voltage Serial Programming Flash, EEPROM, Fuse and Lock Bits may
fail
Writing to any of these locations and bits may in some occasions fail.
Problem Fix/Workaround
After a writing has been initiated, always observe the RDY/BSY
signal. If the writing
should fail, rewrite until the RDY/BSY
verifies a correct writing. This will be fixed in
revision D.
3. Device may lock for further programming
Special combinations of fuse bits will lock the device for further programming effec-
tively turning it into an OTP device. The following combinations of settings/fuse bits
will cause this effect:
– 128 kHz internal oscillator (CKSEL[1..0] = 11), shortest start-up time
(SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled
RSTDISBL = 0.
– 9.6 MHz internal oscillator (CKSEL[1..0] = 10), shortest start-up time
(SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled
RSTDISBL = 0.
– 4.8 MHz internal oscillator (CKSEL[1..0] = 01), shortest start-up time
(SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled
RSTDISBL = 0.
Problem fix/ Workaround
Avoid the above fuse combinations. Selecting longer start-up time will eliminate the
problem.