PCIF0 datasheet(26/294 Pages) ATMEL

26 / 294 page

9219A–RFID–01/11

Atmel ATA5505 [Preliminary]

• Bit 7:1 – Reserved Bits

These bits are reserved for future use and will always read as 0 in Atmel

® AVR®.

• Bits 8:0 – EEAR8:0: EEPROM Address

The EEPROM Address Registers – EEARH and EEARL – specifies the high EEPROM

address in the EEPROM space (see “E2 size” in Table 3-1 on page 19). The EEPROM data

bytes are addressed linearly between 0 and “E2 size”. The initial value of EEAR is undefined.

A proper value must be written before the EEPROM may be accessed.

Note:

For information only - ATtiny47: EEAR8 exists as register bit but it is not used for addressing.

3.5.2

EEDR – EEPROM Data Register

• 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.

3.5.3

EECR – EEPROM Control Register

• Bit 7,6 – Res: Reserved Bits

These bits are reserved for future use and will always read as 0 in the Atmel AVR. After read-

ing, mask out these bits. For compatibility with future Atmel AVR devices, always write these

bits to 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 differ-

ent operations. The Programming times for the different modes are shown in Table 3-2. 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

543210

EEDR7

EEDR6

EEDR5

EEDR4

EEDR3

EEDR2

EEDR1

EEDR0

EEDR

Read/Write

R/W

Initial Value

000000

Bit

543210

–

EEPM1

EEPM0

EERIE

EEMPE

EEPE

EERE

EECR

Read/Write

R/W

Initial Value

Table 3-2.

EEPROM Mode Bits

EEPM1

EEPM0

Typical

Programming Time Operation

3.4ms

Erase and Write in one operation (Atomic Operation)

1.8ms

Erase Only

1.8ms

Write Only

–

Reserved for future use

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