The eeprom address register, The eeprom data register – eedr, The eeprom control register – eecr – Rainbow Electronics ATtiny2313 User Manual
Page 16: Attiny2313, Table 1. eeprom mode bits
16
ATtiny2313
2543A–AVR–08/03
The EEPROM Address
Register
• Bit 7 – Res: Reserved Bit
This bit is reserved in the ATtiny2313 and will always read as zero.
• 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 initial 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 oper-
ation, 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 opera-
tion (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
7
6
5
4
3
2
1
0
–
EEAR6
EEAR5
EEAR4
EEAR3
EEAR2
EEAR1
EEAR0
EEAR
Read/Write
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
X
X
X
X
X
X
X
Bit
7
6
5
4
3
2
1
0
MSB
LSB
EEDR
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
–
–
EEPM1
EEPM0
EERIE
EEMPE
EEPE
EERE
EECR
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
X
X
0
0
X
0
Table 1. EEPROM Mode Bits
EEPM1
EEPM0
Programming
Time
Operation
0
0
3.4 ms
Erase and Write in one operation (Atomic Operation)