attiny25v ATMEL Corporation, attiny25v Datasheet - Page 21

• Manufacturer Part Number: attiny25v
• Description: Microcontroller With 2/4/8k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

5.5.3
2586K–AVR–01/08
EECR – EEPROM Control Register
• Bit 7 – Res: Reserved Bit
This bit is reserved for future use and will always read as 0 in ATtiny25/45/85. For compatibility
with future AVR devices, always write this bit to zero. After reading, mask out this bit.
• Bit 6 – Res: Reserved Bit
This bit is reserved in the ATtiny25/45/85 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
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.
Table 5-1.
• 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 2 – EEMPE: EEPROM Master Program Enable
The EEMPE bit determines whether writing EEPE to one will have effect or not.
When EEMPE is set, setting EEPE within four clock cycles will program the EEPROM at the
selected address. If EEMPE is zero, setting EEPE will have no effect. When EEMPE has been
written to one by software, hardware clears the bit to zero after four clock cycles.
• Bit 1 – EEPE: EEPROM Program Enable
The EEPROM Program Enable Signal EEPE is the programming enable signal to the EEPROM.
When EEPE is written, the EEPROM will be programmed according to the EEPMn bits setting.
The EEMPE bit must be written to one before a logical one is written to EEPE, otherwise no
EEPROM write takes place. When the write access time has elapsed, the EEPE bit is cleared
by hardware. When EEPE has been set, the CPU is halted for two cycles before the next
instruction is executed.
Bit
0x1C
Read/Write
Initial Value
EEPM1
0
0
1
1
EEPM0
EEPROM Mode Bits
0
1
0
1
R
7
–
0
Programming
6
–
R
0
3.4 ms
1.8 ms
1.8 ms
Time
–
EEPM1
R/W
5
X
Operation
Erase and Write in one operation (Atomic Operation)
Erase Only
Write Only
Reserved for future use
EEPM0
R/W
4
X
EERIE
R/W
3
0
EEMPE
R/W
2
0
ATtiny25/45/85
EEPE
R/W
1
X
Table
EERE
5-1. While EEPE
R/W
0
0
EECR
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