ATTINY2313V Ver la hoja de datos (PDF) - Atmel Corporation
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ATTINY2313V Datasheet PDF : 226 Pages
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Figure 10. On-chip Data SRAM Access Cycles
T1
T2
T3
clk
CPU
Address
Data
WR
Data
RD
Compute Address
Address valid
Memory Access Instruction
Next Instruction
EEPROM Data
Memory
The ATtiny2313 contains 128 bytes of data EEPROM memory. It is organized as a separate
data space, in which single bytes can be read and written. The EEPROM has an endurance of at
least 100,000 write/erase cycles. The access between the EEPROM and the CPU is described
in the following, specifying the EEPROM Address Registers, the EEPROM Data Register, and
the EEPROM Control Register. For a detailed description of Serial data downloading to the
EEPROM, see page 172.
EEPROM Read/Write
Access
The EEPROM Access Registers are accessible in the I/O space.
The write access time for the EEPROM is given in Table 1. A self-timing function, however, lets
the user software detect when the next byte can be written. If the user code contains instructions
that write the EEPROM, some precautions must be taken. In heavily filtered power supplies, VCC
is likely to rise or fall slowly on power-up/down. This causes the device for some period of time to
run at a voltage lower than specified as minimum for the clock frequency used. See “Preventing
EEPROM Corruption†on page 20. for details on how to avoid problems in these situations.
In order to prevent unintentional EEPROM writes, a specific write procedure must be followed.
Refer to the description of the EEPROM Control Register for details on this.
When the EEPROM is read, the CPU is halted for four clock cycles before the next instruction is
executed. When the EEPROM is written, the CPU is halted for two clock cycles before the next
instruction is executed.
The EEPROM Address
Register
Bit
Read/Write
Initial Value
7
6
5
4
3
2
1
–
EEAR6 EEAR5 EEAR4 EEAR3 EEAR2 EEAR1
R
R/W
R/W
R/W
R/W
R/W
R/W
0
X
X
X
X
X
X
• Bit 7 – Res: Reserved Bit
This bit is reserved in the ATtiny2313 and will always read as zero.
0
EEAR0
R/W
X
EEAR
16 ATtiny2313
2543L–AVR–08/10
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