
20
4378C–AVR–09/08
AT90PWM1
Bits 15..9 – Reserved Bits
These bits are reserved bits in the AT90PWM1 and will always read as zero.
Bits 8..0 – EEAR8..0: EEPROM Address
The EEPROM Address Registers – EEARH and EEARL specify the EEPROM address in the
512 bytes EEPROM space. The EEPROM data bytes are addressed linearly between 0 and
511. The initial value of EEAR is undefined. A proper value must be written before the EEPROM
may be accessed.
6.3.3
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.
6.3.4
The EEPROM Control Register – EECR
Bits 7..6 – Reserved Bits
These bits are reserved bits in the AT90PWM1 and will always read as zero.
Bits 5..4 – EEPM1 and EEPM0: EEPROM Programming Mode Bits
The EEPROM Programming mode bit setting defines which programming action that will be trig-
gered when writing EEWE. It is possible to program data in one atomic operation (erase the old
operations. The Programming times for the different modes are shown in
Table 1. While EEWE
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.
EEAR7
EEAR6
EEAR5
EEAR4
EEAR3
EEAR2
EEAR1
EEAR0
EEARL
765
4
3
2
1
0
Read/Write
RRRR
R
R/W
Initial Value
0
X
XXX
X
Bit
765
432
10
EEDR7
EEDR6
EEDR5
EEDR4
EEDR3
EEDR2
EEDR1
EEDR0
EEDR
Read/Write
R/W
Initial Value
000
00
Bit
765
43
2
1
0
–
EEPM1
EEPM0
EERIE
EEMWE
EEWE
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