Rainbow Electronics ATtiny861_V - Manual (Page 17)

17
2588B–AVR–11/06
ATtiny261/461/861
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 ATtiny261/461/861 are all accessible through all these addressing modes.
The Register File is described in
”General Purpose Register File” on page 11 .
Figure 6-2. Data Memory Map
6.2.1 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 described in Figure 6-3 .
Figure 6-3. On-chip Data SRAM Access Cycles
6.3 EEPROM Data Memory
The ATtiny261/461/861 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
page 181 .
32 Registers
64 I/O Registers
Internal SRAM
(128/256/512 x 8)
0x0000 - 0x001F
0x0020 - 0x005F
0x0DF/0x15F/0x25F
0x0060
Data Memory
clk
WR
RD
Data
Data
Address Address valid
T1 T2 T3
Compute Address
Read
Wr
ite
CPU
Memory Access Instruction Next Instruction