ATTINY24_1 Datasheet, PDF (16/236 Pages) ATMEL Corporation – 8-bit Microcontroller with 2/4/8K Bytes In-System Programmable Flash

5.2.1
When using register indirect addressing modes with automatic pre-decrement and post-incre-
ment, the address registers X, Y, and Z are decremented or incremented.
The 32 general purpose working registers, 64 I/O Registers, and the 128/256/512 bytes of inter-
nal data SRAM in the ATtiny24/44/84 are all accessible through all these addressing modes.
The Register File is described in “General Purpose Register File” on page 10.
Figure 5-2.
Data Memory Map
Data Memory
32 Registers
64 I/O Registers
0x0000 - 0x001F
0x0020 - 0x005F
0x0060
Internal SRAM
(128/256/512 x 8)
0x0DF/0x015F/0x025F
Data Memory Access Times
This section describes the general access timing concepts for internal memory access. The
internal data SRAM access is performed in two clk_CPU cycles as illustrated in Figure 5-3.
Figure 5-3. 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
5.3 EEPROM Data Memory
The ATtiny24/44/84 contains 128/256/512 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 “Serial Programming” on page 163.
16 ATtiny24/44/84
8006H–AVR–10/09