Datasheet

7701F–AVR–10/12

Atmel ATtiny24/44/84 [Preliminary]

6.3.4 Erase

To erase a byte, the address must be written to EEAR. If the EEPMn bits are 0b01, writing the

EEPE (within four cycles after EEMPE is written) will trigger the erase operation only (pro-

gramming time is given in Table 1). The EEPE bit remains set until the erase operation

completes. While the device is busy programming, it is not possible to do any other EEPROM

operations.

6.3.5 Write

To write a location, the user must write the address into EEAR and the data into EEDR. If the

EEPMn bits are 0b10, writing the EEPE (within four cycles after EEMPE is written) will trigger

the write operation only (programming time is given in Table 1). The EEPE bit remains set until

the write operation completes. If the location to be written has not been erased before write,

the data that is stored must be considered as lost. While the device is busy with programming,

it is not possible to do any other EEPROM operations.

The calibrated oscillator is used to time the EEPROM accesses. Make sure the oscillator fre-

quency is within the requirements described in “Oscillator Calibration Register – OSCCAL” on

page 32.

The following code examples show one assembly function and one C function for erase, write,

or atomic write of the EEPROM. The examples assume that interrupts are controlled (e.g., by

disabling interrupts globally) so that no interrupts will occur during execution of these

functions.