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AT90S8414
Preliminary
4-45
The write access time is in the range of 2.5 - 4ms, depending on the Vcc voltages. A self-timing function, however, lets
the user software detect when the next byte can be written.
The read access time is the same as for the Flash memory and is of no concern to the user software.
THE EEPROM ADDRESS REGISTER - EEAR
Bit
7
6
5
4
3
2
1
0
$1E
MSB
LSB
EEAR
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
Bits 7..0 - EEAR7..0 : EEPROM Address:
The EEPROM Address Register - EEAR7..0 - specifies the EEPROM address in the 256 bytes EEPROM space. The
EEPROM data bytes are addressed linearly between 0 and 255.
THE EEPROM DATA REGISTER - EEDR
Bit
7
6
5
4
3
2
1
0
$1D
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
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
Bit
7
6
5
4
3
2
1
0
$1C
-
-
-
-
-
-
EEWE
EERE
EECR
Read/Write
R
R
R
R
R
R
R/W
R/W
Initial value
0
0
0
0
0
0
0
0
Bits 7..2 - Res : Reserved bits:
These bits are reserved bits in the AT90S8414 and will always be read as zero.
Bit 1 - EEWE : EEPROM Write Enable:
The EEPROM Write Enable Signal EEWE is the write strobe to the EEPROM. When address and data are correctly set
up, the EEWE bit must be set to write the value into the EEPROM. When the write access time (typically 2.5ms at
Vcc=5V or 4ms at Vcc=2.7V) has elapsed, the EEWE bit is cleared (zero) by hardware. The user software can poll this
bit and wait for a zero before writing the next byte.
Bit 0 - EERE : EEPROM Read Enable:
The EEPROM Read Enable Signal EERE is the read strobe to the EEPROM. When the correct address is set up in the
EEAR register, the EERE bit must be set. When the EERE bit is cleared (zero) by hardware, requested data is found in
the EEDR register. The EEPROM read access time is within a single clock cycle and there is no need to poll the EERE
bit.
Содержание AT90S8414
Страница 4: ...4 4 AT90S8414 Preliminary...
Страница 6: ...4 6 AT90S8414 Preliminary Block Diagram Figure 1 The AT90S8414 Block Diagram...
Страница 65: ...AT90S8414 Preliminary 4 65 Figure 50 PORTB Schematic Diagram Pin PB5 Figure 51 PORTB Schematic Diagram Pin PB6...
Страница 68: ...4 68 AT90S8414 Preliminary Figure 53 PORTC Schematic Diagram Pins PC0 PC7...
Страница 87: ...AT90S8414 Preliminary 4 87...