
17
2543L–AVR–08/10
ATtiny2313
Bits 6..0 – EEAR6..0: EEPROM Address
The EEPROM Address Register – EEAR specify the EEPROM address in the 128 bytes
EEPROM space. The EEPROM data bytes are addressed linearly between 0 and 127. The ini-
tial value of EEAR is undefined. A proper value must be written before the EEPROM may be
accessed.
The EEPROM Data
Register – EEDR
Bits 7..0 – EEDR7..0: EEPROM Data
For the EEPROM write operation, the EEDR Register contains the data to be written to the
EEPROM in the address given by the EEAR Register. For the EEPROM read operation, the
EEDR contains the data read out from the EEPROM at the address given by EEAR.
The EEPROM Control
Register – EECR
Bits 7..6 – Res: Reserved Bits
These bits are reserved bits in the ATtiny2313 and will always read as zero.
Bits 5, 4 – EEPM1 and EEPM0: EEPROM Programming Mode Bits
The EEPROM Programming mode bits setting defines which programming action that will be
triggered when writing EEPE. It is possible to program data in one atomic operation (erase the
old value and program the new value) or to split the Erase and Write operations in two different
operations. The Programming times for the different modes are shown in
Table 1. While EEPE is
set, any write to EEPMn will be ignored. During reset, the EEPMn bits will be reset to 0b00
unless the EEPROM is busy programming.
Bit 3 – EERIE: EEPROM Ready Interrupt Enable
Writing EERIE to one enables the EEPROM Ready Interrupt if the I-bit in SREG is set. Writing
EERIE to zero disables the interrupt. The EEPROM Ready Interrupt generates a constant inter-
rupt when Non-volatile memory is ready for programming.
Bit
765
4321
0
MSB
LSB
EEDR
Read/Write
R/W
Initial Value
000
0000
0
Bit
765
43
2
1
0
–
EEPM1
EEPM0
EERIE
EEMPE
EEPE
EERE
EECR
Read/Write
R
R/W
Initial Value
0
X
0
X
0
Table 1. EEPROM Mode Bits
EEPM1
EEPM0
Programming
Time
Operation
0
3.4 ms
Erase and Write in one operation (Atomic Operation)
0
1
1.8 ms
Erase Only
1
0
1.8 ms
Write Only
1
–
Reserved for future use